AMERICAN TOWER CORP /MA/
S-3, 1999-10-20
COMMUNICATIONS SERVICES, NEC
Previous: COBALT NETWORKS INC, S-1/A, 1999-10-20
Next: BROADCOM CORP, DEFS14A, 1999-10-20



    As filed with the Securities and Exchange Commission on October 20, 1999
                                                   Registration No. 333-

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM S-3
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                           AMERICAN TOWER CORPORATION
             (Exact name of registrant as specified in its charter)

               Delaware                                    65-0723837
   (State or other jurisdiction of                      (I.R.S. Employer
    incorporation or organization)                     Identification No.)


               116 Huntington Avenue, Boston, Massachusetts 02116
    (Address, including zip code, and telephone number, including area code,
                  of registrant's principal executive offices)

                                 STEVEN B. DODGE
                           American Tower Corporation
                              116 Huntington Avenue
                           Boston, Massachusetts 02116
                                 (617) 375-7500
 (Name, address, including zip code, and telephone number, including area code,
                             of agent for service)

                                    Copy to:
                             NORMAN A. BIKALES, ESQ.
                            Sullivan & Worcester LLP
                             One Post Office Square
                           Boston, Massachusetts 02109
                                 (617) 338-2800

   Approximate date of commencement of proposed sale to the public: From time to
time after the effective  date of this  registration  statement as determined in
light of market conditions and other factors.
   If the only  securities  being  registered  on this  form are  being  offered
pursuant to dividend or interest reinvestment plans, please check the box. |_|
   If any of the securities being registered on this form are to be offered on a
delayed or continuous  basis  pursuant to Rule 415 under the  Securities  Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, check the following box. |X|
   If this  Form is filed to  register  additional  securities  for an  offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list  the  Securities  Act  registration  statement  number  of the  earlier
effective registration statement for the same offering. |_|
   If this Form is a  post-effective  amendment  filed  pursuant  to Rule 462(c)
under the  Securities  Act,  check the following box and list the Securities Act
registration  statement number of the earlier effective  registration  statement
for the same offering. |_|
   If delivery of the  prospectus  is expected to be made  pursuant to Rule 434,
please check the following box. |_|

<TABLE>
<CAPTION>
                                          CALCULATION OF REGISTRATION FEE
- ---------------------------------------------------------------------------------------------------------------------------------
                                                                     Proposed             Proposed
           Title of Each Class of                  Amount             Maximum              Maximum              Amount of
       Securities to be Registered(1)              to be          Offering Price          Aggregate         Registration Fee
                                                 Registered       Per Security(1)     Offering Price(1)
- ---------------------------------------------------------------------------------------------------------------------------------
<S>                                             <C>                  <C>                <C>                   <C>
6.25% Convertible Notes due 2009.............   $300,000,000         100%               $300,000,000          $83,400
- ---------------------------------------------------------------------------------------------------------------------------------
2.25% Convertible Notes due 2009.............   $425,500,000         70.52%             $300,062,600          $83,418
- ---------------------------------------------------------------------------------------------------------------------------------
Class A Common Stock, par value $.01 per share  24,797,690(2)        N/A                N/A                        N/A(3)
=================================================================================================================================
<FN>
                                                                                           (Footnotes on next page)



<PAGE>


(1)   Estimated  solely for the  purpose of  calculating  the  registration  fee
      pursuant to Rule 457 under the Securities Act of 1933.

(2)   Plus  such  additional  indeterminate  number  of shares of Class A Common
      Stock as may become  issuable  upon  conversion of the 6.25% Notes and the
      2.25% Notes being  registered  hereunder  by reason of  adjustment  of the
      conversion price.

(3)   Pursuant  to Rule  457(i)  under the  Securities  Act of 1933  there is no
      filing fee with  respect to the  shares of Class A Common  Stock  issuable
      upon  conversion  of the 6.25% Notes or 2.25% Notes  because no additional
      consideration  will be received  in  connection  with the  exercise of the
      conversion privilege.
</FN>
</TABLE>

                                 --------------

      The Registrant hereby amends this  Registration  Statement on such date or
dates as may be necessary to delay its effective date until the Registrant shall
file a further  amendment  which  specifically  states  that  this  Registration
Statement shall  thereafter  become effective in accordance with Section 8(a) of
the  Securities  Act of 1933 or until this Registration  Statement  shall become
effective on such date as the Commission,  acting pursuant to said Section 8(a),
may determine.


<PAGE>

We will amend and complete the information in this  prospectus.  Although we are
permitted by U.S.  federal  securities laws to offer these securities using this
prospectus,  we may not sell them or  accept  your  offer to buy them  until the
documentation  filed with the SEC relating to these securities has been declared
effective by the SEC. This  prospectus is not an offer to sell these  securities
or our  solicitation of your offer to buy these  securities in any  jurisdiction
where that would not be permitted or legal.

                  SUBJECT TO COMPLETION, DATED October 20, 1999

                                   PROSPECTUS

                                      LOGO
        $300,000,000                                       $425,500,000
6.25% Convertible Notes Due 2009                2.25% Convertible Notes Due 2009


     This prospectus relates to:

      o     $300,000,000 principal amount of 6.25% convertible notes due 2009,

      o     $425,500,000 principal amount at maturity of 2.25% convertible notes
            due 2009, and

      o     the shares of Class A common stock  issuable upon  conversion of the
            notes.

The notes and the  Class A common  stock  that are  offered  for  resale in this
prospectus  are  offered  for the  accounts  of their  holders.  The notes  were
initially acquired from us in October 1999 in connection with a private offering
by a group of  investment  banking  firms who resold the notes  pursuant to Rule
144A.

     The 6.25% notes are  convertible  at any time prior to maturity into shares
of our Class A common stock at a conversion price of $24.40 per share of Class A
common stock.  This is the equivalent to a conversion  rate of 40.9836 shares of
Class A common stock for each $1,000  principal  amount of the 6.25%  notes.  We
will pay  interest  on the 6.25%  notes on April 15 and October 15 of each year,
commencing on April 15, 2000.

     The 2.25% notes are  convertible  at any time prior to maturity into shares
of our Class A common stock at a conversion price of $24.00 per share of Class A
common  stock,  based on the issue  price of 70.52% of the  principal  amount at
maturity. This is the equivalent to a conversion rate of 29.3833 shares of Class
A common stock for each $1,000  principal amount at maturity of the 2.25% notes.
We will pay interest on the 2.25% notes on April 15 and October 15 of each year,
commencing on April 15, 2000.

     We may redeem the 6.25% notes on or after October 22, 2002. You may require
us to  repurchase  the 6.25%  notes at a price of $1,000  for each 6.25% note on
October 22,  2006.  We may redeem the 2.25% notes on or after  October 22, 2003.
You may require us to repurchase  the 2.25% notes at a price of $802.93 for each
2.25% note on October 22, 2003.  In the case of a repurchase  of notes,  we have
the right to issue shares of Class A common  stock,  rather than to pay cash. In
addition,  you may  require us to  repurchase  the notes of each  series  upon a
change in control.

     Our Class A common stock is listed on the New York Stock Exchange under the
symbol  "AMT." The last  reported  sale price of the Class A common stock on the
New York Stock Exchange on October 19, 1999 was $18.0625 per share.

     Investing in the notes involves risks. See "Risk Factors" beginning on page
12.

     We will not  receive  any of the  proceeds  from  sales of the notes or the
shares by the selling securityholders.

     Neither the  Securities and Exchange  Commission  nor any state  securities
commission has approved or  disapproved  of these  securities or passed upon the
adequacy or accuracy of this prospectus. Any representation to the contrary is a
criminal offense.

               The date of this Prospectus is        , 1999.

<PAGE>





<TABLE>
<CAPTION>
                                                 TABLE OF CONTENTS

<S>                                                  <C>     <C>                                                 <C>
Summary...............................................1      Description of Capital Stock........................39
The Notes.............................................6      Selling Securityholders.............................42
Selected Financial Data...............................9      Certain Federal Income Tax Consequences.............42
Risk Factors.........................................12      Registration Rights Agreement.......................51
Market Prices and Dividend Policy....................18      Plan of Distribution................................52
Unaudited Pro forma Condensed                                Legal Matters.......................................54
  Consolidated Financial Statements..................19      Experts.............................................54
Description of the Notes.............................29      Where You Can Find More Information.................55
</TABLE>


     You  should  rely only on the  information  contained  or  incorporated  by
reference in this prospectus.  We have not authorized anyone to provide you with
information  that is  different.  This  prospectus  may only be used where it is
legal to sell these  securities.  The information in this prospectus may only be
accurate on the date of this prospectus.



                                       -i-

<PAGE>




                                     SUMMARY

     This  summary  highlights  selected  information  about us,  including  our
pending mergers,  acquisitions and other  transactions.  All information in this
prospectus gives effect to pending  transactions,  unless the context  otherwise
indicates.  This  summary  is  not  complete  and  may  not  contain  all of the
information  that you should consider before investing in the notes. All selling
securityholders  must deliver a prospectus to purchasers at or prior to the time
of any sale of the notes or Class A common stock issuable upon conversion of the
notes.  You should  carefully read this entire  prospectus,  including the "Risk
Factors" section  beginning on page 12 and the financial  statements,  which are
incorporated  by reference  from our 1998 Annual  Report,  March 1999  Quarterly
Report,  June 1999  Quarterly  Report and the Current  Report on Form 8-K, dated
September  17,  1999.  We refer to those  reports  together  as the  "Historical
Financial Statements."


                                 AMERICAN TOWER

     We are a  wireless  communications  and  broadcast  infrastructure  company
operating in three business segments.

      o     We operate a leading  network of  communications  towers and are the
            largest  independent  operator  of  broadcast  towers in the  United
            States.

      o     We provide  comprehensive  network development services for wireless
            service providers and broadcasters.

      o     We  operate a leading  teleport  business,  which  transmits  video,
            voice, data and Internet communications worldwide.

     Towers.  We believe we are the  largest  independent  owner,  operator  and
developer  of  wireless  communications  towers in the United  States.  Assuming
consummation of all of the pending  transactions,  we operate a national network
of more than 9,400 multi-user  sites,  8,300 of which are owned or leased towers
and  1,100 of which are  managed  sites.  Our  network  spans 48 states  and the
District  of  Columbia,  with  tower  clusters  in 43 of  the  50  largest  U.S.
metropolitan  statistical  areas. Our primary business is the leasing of antenna
space to a diverse range of wireless communications  industries,  including PCS,
cellular,  ESMR, SMR, paging and fixed microwave. Our wireless customers include
AirTouch,   Alltell,  AT&T,  AT&T  Wireless  Services,   Bell  Atlantic  Mobile,
BellSouth, GTE Mobilnet, Nextel, Omnipoint,  PacBell, PageNet, PowerTel, PrimeCo
PCS, Southwestern Bell, Sprint PCS, Teligent, Western Wireless and WinStar.

     We believe we are the largest independent operator of broadcast towers with
242 sites in the United States and  approximately  200 sites in Mexico. We serve
most of the major radio and television  broadcasters,  including ABC, AMFM, CBS,
Clear  Channel,  CNN, Cox, Fox,  Infinity,  NBC,  Paxson,  Paramount,  Sinclair,
Tribune and Univision.

     Network  Development  Services.  We  are  a  leading  provider  of  network
development  services and  components  for both wireless  service  providers and
broadcasters.  We  offer  full  turnkey  network  development  solutions  to our
customers,  consisting of network  design,  site  acquisition,  zoning and other
regulatory approvals,  construction  management,  tower construction and antenna
installation. We also manufacture wireless infrastructure components. We provide
site acquisition  services to most of the major wireless  service  providers and
have  constructed  or are  constructing  towers  on a  build-to-suit  basis  for
wireless  and  broadcast  companies  such as  AirTouch,  AT&T  affiliates,  AT&T
Wireless Services, Bell South, Nextel, Omnipoint,  Paxson, PrimeCo PCS, Sinclair
and Southwestern Bell.

     We have performed network development  services for other companies on more
than 10,000 sites, including more than 2,150 sites in 1998. In 1998, we embarked
on a major construction program with an emphasis on build-to-suit  projects.  We
constructed  more than 800  towers,  including  more than 500 towers for our own
account, at an aggregate cost of approximately $108.0 million. Our 1999 and 2000
business plans call for construction of more


<PAGE>

than 1,250 towers  annually,  including  more than 1,000 towers in each year for
our own account at an estimated annual cost of between $180.0 million and $200.0
million. These figures do not include the construction of broadcast towers.

     Teleports.  We are a leading video,  voice, data and Internet  transmission
company,  providing  services  worldwide.  We own and operate  approximately 110
satellite  antennas in various  locations  across the United States,  with major
facilities  near New York,  Washington,  D.C.,  Dallas  and San  Francisco.  Our
teleports are used by television networks,  broadcasters,  cable programmers and
many of the leading voice,  data and Internet  providers.  Our customers include
ABC,  British  Telecom,  CBS, CNN,  Deutsche  Telekom,  Fox, MCI Worldcom,  TCI,
Telefonica and Uunet.

     For the year ended  December  31,  1998,  we had pro forma net  revenues of
$273.1  million and EBITDA of $91.9  million.  For the six months ended June 30,
1999,  we had pro  forma net  revenues  of $146.5  million  and  EBITDA of $52.5
million. This pro forma data includes the results of major acquisitions, but not
all of them.

     We estimate that our three  business  segments  accounted for the following
percentages of pro forma 1998 operating revenues:

      o     Towers--56%,

      o     Network development services--37%, and

      o     Teleports--7%.

     We  believe  that site  leasing  activities  generate  the  highest  profit
margins.  We also believe that leasing  activities  are likely to grow at a more
rapid  rate  than  other  segments  of  our  business  because  of  our  pending
acquisitions and our  build-to-suit  and other  construction  activities.  These
acquisitions and construction  activities will increase significantly the number
of antenna sites available for leasing.  The industry trend towards  outsourcing
infrastructure  needs may also result in a decline in our site  acquisition  and
construction activities for other companies.

     We have a  diversified  base of more  than  5,300  customers.  Our  largest
customer,  AirTouch, accounted for approximately 25% of our pro forma annualized
August  1999  operating  revenues.  Our five  largest  customers  accounted  for
approximately 46% of those revenues.  Annualized August 1999 revenues may not be
representative of historical  revenues because revenues from service  activities
are  highly  variable  due to  their  transactional  nature.  For  example,  one
customer, Sprint PCS, accounted for approximately 11% of our pro forma operating
revenues  for the six months  ended June 30,  1999,  principally  as a result of
several site acquisition projects during that period.

     We estimate that personal  communications  services  ("PCS")  accounted for
more  than 28% of our pro  forma  annualized  August  1999  operating  revenues,
cellular  accounted for approximately 16% of those revenues and paging accounted
for  approximately  12% of those  revenues.  We believe  that no other  industry
sector  accounted  for as much as 10% of those  revenues.  We believe,  however,
these  industry  sector  percentages  may  not be  indicative  of  what  we will
experience in the future.  The importance of the different sectors will probably
change because of the anticipated growth of PCS, cellular and ESMR,  compared to
other wireless service  providers.  The relative  contributions of the different
sectors  will  also be  affected  as major  wireless  service  providers  create
strategic alliances with independent  operators,  including in our case AirTouch
and AT&T.  Finally,  the percentage of operating  revenues derived from PCS will
also be  affected  by the  decline  in our  site  acquisition  and  construction
activities  for  that  sector,   as  providers   continue  to  outsource   those
requirements.

                                      -2-
<PAGE>



Growth Strategy

     We designed our growth  strategy to create and then enhance our position as
a leader in each of our business segments. Our goals were:

      o     to create a national footprint of desirable communications towers in
            all major markets in the United States,

      o     to establish the capacity to serve all of the  infrastructure  needs
            of the wireless service and broadcast industries, and

      o     to create a leading teleport company with global reach.

     We  implemented  our strategy  through a combination  of  acquisitions  and
construction.   Acquisitions  were  pursued  initially  with  independent  tower
operators and other  consolidators and more recently with major wireless service
providers  selling their towers.  This  acquisition  strategy also broadened the
scope of our network development services.

     Our  strategy  has  enabled  us to create an  organization  with a depth of
personnel,  computer and financial systems, sales and marketing, and engineering
and other  technical  expertise  to take  advantage  of the  growth in  wireless
communications,  digital  television  and the  Internet.  We believe we are well
positioned  competitively  for  growth  because  we can  meet  the  majority  of
infrastructure  requirements of wireless  communications  and digital television
and are playing an increasing  role in addressing the Internet's  infrastructure
needs. We will continue to pursue our growth strategy by:

      o     maximizing  utilization of antenna sites through  targeted sales and
            marketing techniques,

      o     capitalizing   on  our  ability  to  provide  full  turnkey  network
            development solutions principally through build-to-suit projects and
            other tower construction activities, and

      o     pursuing strategic  acquisitions,  designed  principally (a) to take
            advantage of divestiture opportunities presented by wireless service
            providers,  (b) to facilitate entry into new geographic  markets and
            (c) to complement our construction program.


Recent Developments

   Consummated Transactions

     Since  January  1,  1999,  we have  consummated  more than 45  transactions
involving the acquisition of  approximately  1,500  communications  sites for an
aggregate  purchase  price of $945.8  million.  This purchase price includes the
payment of  approximately  $352.2  million in cash, the issuance of 20.7 million
shares of Class A common  stock,  and the  assumption  of  approximately  $145.0
million of debt. The principal transactions were the following:

     OmniAmerica  merger.  In February  1999,  we  consummated  the  OmniAmerica
merger.  OmniAmerica owned or co-owned 223 towers in 24 states. OmniAmerica also
offered nationwide turnkey tower construction and installation  services through
its Specialty Constructors  subsidiary and manufactured wireless  infrastructure
components.  The aggregate  consideration was $462.0 million,  consisting of the
issuance of 16.8 million  shares of Class A common stock and the  assumption  of
$96.6 million of debt. We also assumed  certain Omni employee stock options that
were  converted  into options to purchase  approximately  1.0 million  shares of
Class A common stock.

     TeleCom  merger.  In February  1999,  we  consummated  the TeleCom  merger.
TeleCom   owned  or   co-owned   approximately   271  towers  and   managed  121
revenue-generating  sites in 27 states.  The aggregate merger

                                      -3-
<PAGE>

consideration was $194.6 million,  consisting of the payment of $63.1 million in
cash,  the  issuance  of 3.9  million  shares of Class A common  stock,  and the
assumption of $48.4 million of debt.

     Triton PCS  acquisition.  In  September  1999,  we  acquired  187  wireless
communications  towers from Triton PCS,  the first  member of the AT&T  Wireless
Network,  for $70.7 million in cash. We expect to consummate the purchase of the
remaining  four  communications  towers  for $1.5  million in cash in the fourth
quarter of 1999.  The  towers are  located in  Georgia,  North  Carolina,  South
Carolina and Virginia. We will develop a minimum of 100 build-to-suit towers for
Triton PCS and  provide  turnkey  services to Triton PCS for  co-location  sites
through 2001. The master lease  agreement will provide Triton PCS with a 12-year
lease  and  three,  five-year  renewal  terms for  existing  towers  and  future
build-to-suit  towers. The initial rents are $1,200 per month, per antenna site,
subject to an annual 3% escalator.


   Pending Transactions

     We are a party to 15 pending transactions involving the acquisition of more
than 5,070  communications  sites and a major teleport  complex for an aggregate
purchase price of $1.7 billion.  These transactions remain subject to regulatory
approvals  in  certain  cases and other  conditions.  Our  pending  transactions
represent  a recent  shift  in our  acquisition  focus  from  independent  tower
operators and other consolidators to major wireless service providers seeking to
sell their towers. The principal transactions are the following:

     AirTouch  transaction.  In August  1999,  we agreed to lease on a long-term
basis 2,100 towers from AirTouch Communications. These towers are located in all
of AirTouch's  major  markets,  other than Los Angeles and San Diego,  including
Albuquerque,  Atlanta, Cleveland, Denver, Detroit, Minneapolis,  Omaha, Phoenix,
Portland,  San Francisco and Seattle.  At closing,  we will pay AirTouch  $800.0
million in cash and deliver a five-year warrant to purchase  3,000,000 shares of
Class A common stock at $22.00 per share.

     Under the lease, we are entitled to all income generated from leasing space
on the towers and are responsible for the payment of all expenses of the towers,
including  ground  rent.  AirTouch  has  reserved  space on the  towers  for its
antennas, for which it will pay us a site maintenance charge equal to $1,500 per
month  for  each  non-microwave  reserved  space  and $385  per  month  for each
microwave reserved space.

     At  closing  we will  enter  into  an  exclusive  three-year  build-to-suit
agreement with AirTouch.  Under that agreement,  we will have the right to build
all of AirTouch's  towers in all of the markets  covered by the lease.  AirTouch
will enter into a separate master lease covering all towers constructed pursuant
to the  build-to-suit  agreement.  AirTouch will lease space for a period of ten
years and will have the option to extend for five,  five-year periods.  The rent
will be $1,500 per month for each non-microwave  antenna site and $385 per month
for each  microwave  antenna site,  with annual  increases of 3%. We expect this
build-to-suit agreement will produce 400 to 500 towers.

     The transaction  will be closed in stages,  subject to the  satisfaction of
customary  conditions,  beginning  in the  fourth  quarter of this year or first
quarter of 2000.

     AT&T  transaction.  In September  1999, we agreed to purchase  1,942 towers
from  AT&T.  These  towers are  located  throughout  the United  States and were
constructed  by  AT&T  for  its  microwave  operations.  We  will  enter  into a
build-to-suit  agreement with AT&T Wireless  Services at the initial  closing of
the  transaction.  The  purchase  price is $260.0  million  in cash,  subject to
adjustment if all towers are not purchased.

     At the  initial  closing,  AT&T will  enter into a master  lease  agreement
covering those towers we will acquire on which it conducts microwave operations.
The lease  will have an  initial  term of ten  years,  and AT&T will have  five,
five-year renewal options.  The annual base rent for the microwave operations is
approximately $1.0 million,  payable in January of each lease year. In addition,
the rent will be adjusted  based upon AT&T's use of the towers,  except that any
downward  adjustment  can be  used  by  AT&T as a  credit  only  against  future
additional  rent and not

                                      -4-
<PAGE>

against the base rent. AT&T currently uses 468 of these towers for its microwave
operations.  We expect that as many as 50% of the towers may not be  marketable,
at least in the near future, because of location.

     AT&T  Wireless  Services  uses  and will  lease  from us space on 90 of the
towers to be purchased by us. At the initial  closing,  AT&T  Wireless  Services
will enter into an amendment to its existing master lease with us to lease those
sites at a monthly rent of $1,350 per site, increasing by 4% per year.

     Our build-to-suit  agreement with AT&T Wireless Services will require it to
present us 1,200 sites  nationwide  from which we will have the  opportunity  to
build 1,000  towers.  There will be a separate  master lease with AT&T  Wireless
Services for the build-to-suit  towers.  The initial term will be ten years, and
AT&T will have three, five-year renewals. The rent for lease supplements entered
into in the  initial  year is $1,350 per month,  per  antenna  site,  increasing
annually by $50 per year for lease supplements entered into in subsequent years.
All rents will be subject to a 4% per annum escalator.

     The transaction  will be closed in stages,  subject to the  satisfaction of
customary  conditions,  including  the  receipt  of  all  regulatory  approvals,
beginning in the fourth quarter of this year or the first quarter of 2000.

     UNIsite merger. In June 1999, we agreed to a merger with UNIsite.  Based on
UNIsite  owning 600  completed  towers at closing,  the  purchase  price will be
$205.0 million,  $165.0 million of which is payable in cash and $40.0 million in
assumption of UNIsite's debt. The purchase price is subject to adjustment  based
on (a) the net working  capital and the long-term debt of UNIsite at closing and
(b) the number of completed  towers.  UNIsite's towers are located  primarily in
the  Northeast and Midwest.  Subject to the  satisfaction  of customary  closing
conditions,  including approval under our credit facilities,  the UNIsite merger
is expected to be consummated in the first quarter of 2000.

     TV Azteca  acquisition.  In  September  1999,  we entered  into a letter of
intent  with TV  Azteca,  the  owner of a major  national  television  broadcast
network in Mexico,  relating to  approximately  200  broadcast  towers.  We have
agreed  to  loan  up to  $120.0  million  to  that  company  and  to  take  over
responsibility for marketing and certain  maintenance  functions for the towers.
The 20-year loan,  which may be extended for an  additional 20 years,  will bear
net interest at approximately 11% per annum. We will be entitled to receive 100%
of the revenues generated by third party leases on the towers during the term of
the loan. We have made an interim loan of $60.0  million.  The interim loan will
mature on the earlier of March 17, 2000 or the closing of the  transaction.  The
closing is subject to certain  conditions,  including the execution and delivery
of definitive  agreements and the receipt of all necessary regulatory approvals.
Subject to satisfaction of those conditions, definitive agreements are scheduled
to be executed in the fourth quarter of 1999.

     ICG  transaction.  In August 1999, we agreed to acquire all of the stock of
ICG Satellite Services and its subsidiary,  Maritime Telecommunications Network,
Inc.,   for  $100.0  million  in  cash.   The   acquisition   involves  a  major
around-the-clock   teleport  facility  in  New  Jersey  and  a  global  maritime
telecommunications network headquartered in Miami, Florida. The acquired company
provides voice, data,  Internet and compressed video satellite services to major
cruise lines, the U.S.  military,  Internet-related  companies and international
telecommunications  customers. The New Jersey teleport and operations center has
12 existing antennas and one under construction that access satellites  covering
the  continental  U.S.,  South  America  and  the  Atlantic  Ocean  region.  The
transaction  is  expected  to close in the fourth  quarter  of 1999,  subject to
satisfaction of customary conditions.

     Watson   transaction.   In  July  1999,   we  agreed  to   acquire   Watson
Communications  for $73.0 million in cash. The acquisition  involves 11 wireless
and 10 broadcast  towers in the San  Francisco  Bay area and one  teleport  that
contains nine  antennas.  The teleport  covers the full domestic and the Pacific
international  service region. Among the acquired sites is San Bruno Mountain, a
premiere location within the San Francisco  market.  The transaction is expected
to close in the fourth quarter of 1999, subject to the satisfaction of customary
conditions.

         Credit Facilities  Amendment.  We currently have credit facilities that
provide for borrowings of up to $483.0 million.  We are seeking to negotiate new
credit facilities that would provide for borrowings of up to $2.0

                                      -5-
<PAGE>

billion.  As of  October  15,  1999,  we  had no  borrowings  under  our  credit
facilities and available cash of $154.0  million.  On a pro forma basis,  giving
effect as of that date to all pending transactions,  we would have had aggregate
borrowings  under our credit  facilities  of  approximately  $1.1 billion and no
available  cash. We must arrange for  additional  borrowings  or other  external
funds  in  order  to  complete  all of our  pending  transactions.  There  is no
assurance that we will  successfully  negotiate new credit facilities or that we
will obtain our desired  new  borrowing  level.  The new credit  facilities  may
involve  different  and  more  restrictive  covenants  or other  terms  than our
existing credit facilities. Upon the execution of a new credit facility, we will
be required to recognize an extraordinary loss on extinguishment of debt. If the
new credit  facility is executed in the fourth quarter of 1999,  such loss would
be  approximately  $4.5  million,  net of a tax  benefit of  approximately  $3.0
million.

         Private  Placement  of the Notes.  On  October  4, 1999,  we closed the
private sale of the notes to  institutional  investors.  Our net  proceeds  were
approximately  $584.0 million, of which we used approximately  $368.0 million to
repay all outstanding  borrowings under our credit  facilities.  We invested the
balance in short-term,  investment grade securities on an interim basis and will
use those funds to finance pending acquisitions and construction activities.

     Our  principal  executive  offices  are located at 116  Huntington  Avenue,
Boston, Massachusetts 02116. Our telephone number is (617) 375-7500.


                                    THE NOTES

Securities Offered.................... 6.25%   notes:   $300,000,000   principal
                                       amount  of 6.25%  Convertible  Notes  Due
                                       2009  previously   issued  in  a  private
                                       placement. We refer to those notes as the
                                       6.25% notes.

                                       2.25%   notes:   $425,500,000   principal
                                       amount at maturity  of 2.25%  Convertible
                                       Notes  Due 2009  previously  issued  in a
                                       private placement.  This is equivalent to
                                       total  proceeds  at the  issue  price  of
                                       $300,062,600.  We refer to those notes as
                                       the 2.25%  notes and,  together  with the
                                       6.25% notes, as the notes.

Issue Price........................... 6.25% notes:  100% plus accrued interest,
                                       if any, from the date of issue.

                                       2.25%   notes:    70.52%   plus   accrued
                                       interest, if any, from the date of issue.

Interest.............................. 6.25%  notes:  6.25%  per  annum  on  the
                                       principal amount, payable semiannually in
                                       arrears  in cash on April 15 and  October
                                       15 of  each  year,  beginning  April  15,
                                       2000.

                                       2.25%  notes:  2.25%  per  annum  on  the
                                       principal amount, payable semiannually in
                                       arrears  in cash on April 15 and  October
                                       15 of  each  year,  beginning  April  15,
                                       2000.

Yield to Maturity..................... 6.25% notes:  6.25% per annum  calculated
                                       on a  semiannual  basis  from  October 4,
                                       1999.

                                       2.25% notes: 6.25% per annum,  calculated
                                       on a semiannual  basis giving effect both
                                       to accrued original issue discount and to
                                       accrued interest from October 4, 1999.

Conversion Rights..................... 6.25%  notes:  You may  convert the 6.25%
                                       notes  at any time on or  before  October
                                       15,  2009,  unless  we have  redeemed  or
                                       purchased   them.  The  6.25%  notes  are
                                       convertible into shares of Class A common
                                       stock at a conversion price of $24.40 per
                                       share.  We will deliver 40.9836 shares of

                                      -6-
<PAGE>

                                       Class A  common  stock  for  each  $1,000
                                       principal  amount  of 6.25%  notes.  Upon
                                       conversion  you will not receive any cash
                                       payment representing accrued interest.

                                       2.25%  notes:  You may  convert the 2.25%
                                       notes  at any time on or  before  October
                                       15,  2009,  unless  we have  redeemed  or
                                       purchased   them.  The  2.25%  notes  are
                                       convertible into shares of Class A common
                                       stock at a conversion price of $24.00 per
                                       share.  We will deliver 29.3833 shares of
                                       Class A  common  stock  for  each  $1,000
                                       principal  amount  at  maturity  of 2.25%
                                       notes.  We will not adjust the conversion
                                       rate for accrued  original issue discount
                                       or interest.  Upon  conversion,  you will
                                       not receive any cash payment representing
                                       accrued   original   issue   discount  or
                                       interest.

                                       The  conversion  rate of both  series  of
                                       notes is subject to adjustment in certain
                                       events.

Maturity Date......................... October 15, 2009.

Change in Control..................... If a change  in  control  of our  company
                                       occurs,  you may  require us to  purchase
                                       your  notes for cash at a price  equal to
                                       the principal  amount, in the case of the
                                       6.25%  notes,  and the issue  price  plus
                                       accrued  original  issue  discount in the
                                       case of the 2.25% notes.  In each case we
                                       will also be  required to pay accrued and
                                       unpaid  interest.   Our  existing  credit
                                       facilities  prohibit  making these change
                                       in control  payments without bank consent
                                       until December 2006.

Optional Redemption................... 6.25%  notes:  We  will  not be  able  to
                                       redeem the 6.25%  notes  prior to October
                                       22, 2002. Thereafter, we can redeem those
                                       notes, at our option, in whole or in part
                                       at  a  redemption   price   initially  of
                                       103.125%  of the  principal  amount.  The
                                       redemption    price   declines    ratably
                                       immediately  after  October  15  of  each
                                       following  year to 100% of the  principal
                                       amount in 2005.  We are also  required to
                                       pay accrued and unpaid interest.

                                       2.25%  notes:  We  will  not be  able  to
                                       redeem the 2.25%  notes  prior to October
                                       22, 2003. Thereafter, we can redeem those
                                       notes, at our option, in whole or in part
                                       at increasing  redemption prices designed
                                       to reflect  the  accrued  original  issue
                                       discount.  We are  also  required  to pay
                                       accrued and unpaid interest.

Repurchase of Notes at
  Your Option......................... 6.25%  notes:   You  may  require  us  to
                                       repurchase all or any of your 6.25% notes
                                       on October  22,  2006 at their  principal
                                       amount,  together with accrued and unpaid
                                       interest.

                                       2.25%  notes:   You  may  require  us  to
                                       repurchase all or any of your 2.25% notes
                                       on October 22, 2003 at $802.93,  which is
                                       its issue  price  plus  accrued  original
                                       issue discount, together with accrued and
                                       unpaid interest.

                                       We may, at our  option,  elect to pay the
                                       repurchase  price of each  series in cash
                                       or shares of Class A common stock, or any
                                       combination  thereof. Our existing credit
                                       facilities  require us to pay entirely in
                                       stock unless we obtain bank consent.

Sinking Fund.......................... None.

                                      -7-
<PAGE>

Original Issue Discount
  on 2.25% Notes...................... Each 2.25% note was issued with  original
                                       issue  discount  for  federal  income tax
                                       purposes.  The amount of the  discount is
                                       the  difference   between  the  principal
                                       amount of the 2.25% note at maturity  and
                                       its issue price. You should be aware that
                                       accrued  original  issue discount will be
                                       includable  periodically  in  your  gross
                                       income for  federal  income tax  purposes
                                       before  conversion,   redemption,   other
                                       disposition  or  maturity  of your  2.25%
                                       notes,  whether  or not  those  notes are
                                       ultimately converted,  redeemed,  sold to
                                       us or others or paid at maturity.

Ranking............................... The  notes of the two  series  will  rank
                                       equally  with one  another.  Both  series
                                       will    effectively    rank   junior   to
                                       indebtedness outstanding under the credit
                                       facilities since all of that indebtedness
                                       is  issued  by  our  subsidiaries  and is
                                       secured,  directly or indirectly  through
                                       guarantees,   by   the   assets   of  our
                                       subsidiaries.

Registration Rights................... We   have   agreed   to   keep   the  SEC
                                       registration statement that includes this
                                       prospectus  useable until October 4, 2001
                                       or any shorter period permitted under the
                                       SEC rules permitting unregistered resales
                                       of  privately  placed   securities.   The
                                       interest  rate on the notes will increase
                                       if we are  not in  compliance  with  this
                                       requirement.

Use of Proceeds....................... We will not receive any proceeds from the
                                       sale by the  selling  securityholders  of
                                       the  notes or the  shares  issuable  upon
                                       conversion.

Trading............................... The notes are not listed and trade on the
                                       over-the-counter   market.  The  Class  A
                                       common  stock is listed on the NYSE under
                                       the symbol "AMT."

Common Stock Outstanding(1).......... 144,466,550 shares of Class A common stock
                                        8,811,940 shares of Class B common stock
                                        2,422,804 shares of Class C common stock
                                      -----------
                                      155,701,294 shares of common stock
                                      ===========

(1)  The  number of shares of common  stock  outstanding  was  determined  as of
     October 1, 1999.  This number  does not include  shares we may issue in the
     future  upon  conversion  of other  securities.  Examples  of these  future
     issuances  include:  (a)  shares  of Class A  common  stock  issuable  upon
     conversion  of Class B common  stock or Class C common  stock,  (b)  shares
     issuable  upon  exercise of options  currently  outstanding  to purchase an
     aggregate  of  13,774,198  shares of common  stock,  (c)  3,000,000  shares
     issuable  upon  exercise  of the  warrant  to be  issued  in  the  AirTouch
     transaction,  or (d)  24,797,690  of Class A  common  stock  issuable  upon
     conversion of the notes.

                                      -8-
<PAGE>






                             SELECTED FINANCIAL DATA

     We have derived the following  selected  financial data from our historical
consolidated   financial  statements  and  our  unaudited  pro  forma  condensed
consolidated financial statements. The selected financial data should be read in
conjunction with the Historical  Financial  Statements.  Prior to our separation
from our former  parent on June 4, 1998, we operated as a subsidiary of American
Radio  Systems  and not as an  independent  company.  Therefore,  our results of
operations  for that period may be different  from what they would have been had
we operated as a separate, independent company.

     Year-to-year comparisons are significantly affected by our acquisitions and
construction  of towers,  both of which have been  numerous  during the  periods
presented.  Our principal acquisitions are described in "American  Tower--Recent
Developments"  under  "Summary"  on page 3 and in the  notes  to the  Historical
Financial Statements.

     The pro forma balance sheet data gives effect,  as of June 30, 1999, to the
pro forma transactions not then consummated:  the AirTouch transaction, the AT&T
transaction, the UNIsite merger and the notes placement. The pro forma statement
of  operations  data and  other  operating  data  gives  effect to the pro forma
transactions,  as if each had  occurred on January 1, 1998.  We use the term pro
forma  transactions to mean certain of our major  acquisitions and financings as
follows:  the  OmniAmerica  merger,  the TeleCom  merger,  the  separation  from
American  Radio  Systems,  the ATC merger,  the Wauka  transaction,  the UNIsite
merger, the AirTouch transaction,  the AT&T transaction, our public offerings in
July 1998 and February  1999 and our private  placements in February and October
1999. Pro forma  transactions  do not include all of the  consummated or pending
acquisitions or pending construction.  See "American Tower--Recent Developments"
under  "Summary"  on page 3 and  "Unaudited  Pro  Forma  Condensed  Consolidated
Financial Statements" on page 19.

     We account for all of the included  acquisitions  as purchases.  This means
that for accounting and financial reporting purposes,  we include the results of
the  acquired  companies  or  assets  with ours only  after the  closing  of the
acquisition.  The pro forma  financial  data reflects  certain  adjustments,  as
explained  elsewhere in this  prospectus.  Therefore,  any comparison of the pro
forma financial data with the historical  financial data for periods before 1998
is  inappropriate.  See "Unaudited Pro Forma  Condensed  Consolidated  Financial
Statements" on page 19.

     We use the term "tower cash flow" to mean  operating  income  (loss) before
depreciation and amortization,  tower separation  expenses and corporate general
and  administrative  expenses.  We use the term "tower  separation  expenses" to
refer to the  one-time  expenses  incurred  as a result of our  separation  from
American Radio Systems.  We use "EBITDA" to mean operating  income (loss) before
depreciation and amortization  and tower  separation  expenses.  "After-tax cash
flow" means income (loss) before  extraordinary  losses,  plus  depreciation and
amortization. We do not consider tower cash flow, EBITDA and after-tax cash flow
as a substitute for alternative  measures of operating results or cash flow from
operating  activities or as a measure of our  profitability or liquidity.  These
measures of performance are not calculated in accordance with generally accepted
accounting principles. However, we have included them because they are generally
used in the communications  site industry as a measure of a company's  operating
performance.  More specifically, we believe they can assist in comparing company
performances  on  a  consistent   basis  without  regard  to  depreciation   and
amortization.  Our  concern  is that  depreciation  and  amortization  can  vary
significantly  among  companies  depending on accounting  methods,  particularly
where  acquisitions  are  involved,   or  on  non-operating   factors  including
historical  cost bases.  We believe tower cash flow is useful because it enables
you to compare  tower  performances  before the effect of tower  separation  and
corporate  general and  administrative  expenses that do not relate  directly to
performance.

                                      -9-
<PAGE>




<TABLE>
<CAPTION>
                                                     AMERICAN TOWER CORPORATION

                                                     Selected Financial Data(1)


                                         July 17, 1995     Year Ended        Year Ended          Six Months Ended
                                          (inception)     December 31,   December 31, 1998         June 30, 1999
                                            through       -----------   --------------------   ---------------------
                                       December 31, 1995  1996   1997   Historical Pro Forma   Historical  Pro Forma
                                       -----------------  ----   ----   ---------- ---------   ----------  ---------
                                                         (in thousands, except per share data)
<S>                                        <C>         <C>      <C>      <C>       <C>        <C>          <C>
Statements of Operations Data:
Operating revenues...................          $163     $2,897  $17,508  $103,544  $273,092    $101,561    $146,482
                                               ----     ------  -------  --------  --------    --------    --------
Operating expenses:
  Operating expenses excluding
   depreciation and amortization,
   tower separation, and corporate
   general and administrative expenses           60      1,362    8,713    61,751   172,624      59,020      88,047
  Depreciation and amortization......            57        990    6,326    52,064   212,859      57,808     111,632
  Tower separation expenses..........                                      12,772    12,772
  Corporate general and administrative
    expenses.........................           230        830    1,536     5,099     8,599       4,140       5,890
                                           --------    -------  -------  --------  --------   ---------    --------
    Total operating expenses.........           347      3,182   16,575   131,686   406,854     120,968     205,569
                                           --------    -------  -------  --------  --------   ---------    --------
(Loss) income from operations........          (184)      (285)     933   (28,142) (133,762)    (19,407)    (59,087)
Interest expense.....................                            (3,040)  (23,229)              (11,539)    (59,559)
                                                                                   (114,821)
Interest income and other, net.......                       36      251     9,217     9,217      10,737      10,737
Minority interest in net (earnings)
losses of subsidiaries (2)                                (185)    (193)     (287)     (287)         79          79
                                           --------    -------  -------  --------  --------   ---------    --------
Loss before income taxes and
extraordinary losses.................          (184)      (434)  (2,049)  (42,441) (239,653)    (20,130)   (107,830)
Benefit (provision) for income taxes.            74        (45)     473     4,491    70,091         747      31,535
                                           --------    -------  -------  --------  --------   ---------    --------
Loss before extraordinary losses.....         $(110)     $(479) $(1,576) $(37,950)$(169,562)   $(19,383)   $(76,295)
                                           ========    =======  =======  ========  ========   =========    ========
Basic and diluted loss per common share
  before extraordinary losses(3).....        $(0.00)    $(0.01)  $(0.03)   $(0.48)   $(1.10)     $(0.14)     $(0.49)
                                           ========    =======  =======  ========  ========   =========    ========
Basic and diluted weighted average
  common shares outstandings(3)......        48,732     48,732   48,732    79,786   154,658     143,503     155,519
                                           ========    =======  =======  ========  ========   =========    ========

Other Operating Data:
Ratio of earnings to fixed charges(4)            --         --       --        --        --          --          --
Tower cash flow......................          $103     $1,535   $8,795   $41,793  $100,468     $42,541     $58,435
EBITDA...............................          (127)       705    7,259    36,694    91,869      38,401      52,545
EBITDA margin........................          (N/A)     24.3%    41.5%     35.4%     33.6%       37.8%       35.9%
After-tax cash flow..................           (53)       511    4,750    14,114    43,297      38,425      35,337
Cash provided by (used for) operating
  activities.........................          (51)      2,230    9,913    18,429        --      25,844          --
Cash used for investing activities...            --         -- (216,783) (350,377)       --    (300,787)         --
Cash provided by financing activities            63        132  209,092   513,527        --     441,989          --


<CAPTION>
                                                                                                 Six Months Ended
                                                                                 December 31,      June 30, 1999
                                                                                -------------   --------------------
                                                                                1997     1998   Historical Pro Forma
                                                                                ----     ----   ---------- ---------

<S>                                                                              <C>    <C>       <C>       <C>
Tower Data:
Towers operated at end of period(5)........................................      674    2,492     3,644     9,271
Towers constructed(6)......................................................       84      503       445       n/a


                                                                -10-
<PAGE>


<CAPTION>
                                                                 Year Ended December 31,
                                                                       Historical                   June 30, 1999
                                                                       ----------                   -------------
                                                              1995(1)    1996   1997    1998     Historical Pro Forma
                                                              -------    ----   ----    ----     ---------- ---------
                                                                                (in thousands)
<S>                                                           <C>    <C>      <C>      <C>        <C>        <C>
Balance Sheet Data:
Cash and cash equivalents.................................    $  12   $2,373  $ 4,596  $ 186,175  $ 353,221  $ 360,147
Working capital (deficiency), excluding current portion of
long-term debt............................................      (40)     663   (2,208)    93,602    352,848    349,748
Property and equipment, net...............................    3,759   19,710  117,618    449,476    725,846    725,846
Unallocated purchase price................................      --        --      --          --         --  1,367,712
Total assets..............................................    3,863   37,118  255,357  1,502,343  2,518,576  3,912,127
Long-term debt, including current portion.................      --     4,535   90,176    281,129    284,121    972,057
Convertible notes, net of discount........................      --        --      --          --         --    600,000
Total stockholders' equity................................    3,769   29,728  153,208  1,091,746  2,161,933  2,207,433

<FN>
- --------------
(1)   We were organized on July 17, 1995.
(2)   Represents the minority interest in net (earnings) losses of our non wholly-owned subsidiaries.
(3)   Basic and diluted loss per common share before  extraordinary  losses has been  computed  using (a) in the case of  historical
      information,  for periods prior to June 4, 1998, the number of shares outstanding following the separation from American Radio
      Systems and (b) in the case of pro forma information,  the number of shares expected to be outstanding following the pro forma
      transactions.
(4)   For purposes of calculating  this ratio,  "earnings"  consist of loss before income taxes and  extraordinary  losses and fixed
      charges.  "Fixed  charges"  consist of interest  expense,  amortization  of debt discount and related  issuance  costs and the
      component of rental  expense  believed by management to be  representative  of the interest  factor on that expense.  We had a
      deficiency in earnings to fixed charges in each period as follows (in millions):  1995--$184;  1996--$434;  1997--$2,049; 1998
      (historical)--$42,441; and 1999 (six months ended June 30, historical)--$20,130.
(5)   Includes  information with respect to our company only and assumes consummation of all pending  transactions,  including those
      not included in the pro forma transactions. Does not include towers under construction. See Note (6) below.
(6)   Includes towers constructed in each period by us, including towers  constructed for and owned by third parties.  These numbers
      do not include towers constructed by companies we acquired during the applicable period.
</FN>
</TABLE>


                                      -11-
<PAGE>




                                  RISK FACTORS

     You should consider  carefully the following  factors and other information
in this prospectus before deciding to invest in our securities.


If we cannot keep raising capital, our growth will be impeded

     Without  additional  capital,  we would need to curtail our acquisition and
construction programs. We expect to use borrowed funds for most of this capital.
However,  we must  continue  to  satisfy  financial  ratios  and to comply  with
financial  and other  covenants in order to do so. If our revenues and cash flow
do not meet  expectations,  we may lose our ability to borrow money.  These same
factors,  as well  as  market  conditions  beyond  our  control,  could  make it
difficult or impossible for us to sell stock as an alternative to borrowing.

     As explained below, we do not have sufficient  borrowing capacity under our
credit  facilities to finance all of our pending  acquisitions.  See "Our future
commitments for pending  transactions  exceed our currently  available funds" on
page 14.


Meeting payments on our large debt could be a burden to us

     Our high debt level makes us  vulnerable  to downturns  in our  operations.
This high debt level  requires us to use most of our cash flow to make  interest
and principal  payments.  If we do not generate sufficient cash flow through our
operations  to make interest and  principal  payments,  we may be forced to sell
debt or equity  securities  or to sell some of our core  assets.  This  could be
harmful to our business and to our securityholders. Market conditions or our own
financial situation may require us to make these sales on unattractive terms.


Demand for tower space may be beyond our control

     Many of the factors affecting the demand for tower space, and therefore our
cash flow, are beyond our control. Those factors include:

      o     consumer demand for wireless services,

      o     the  financial  condition of wireless  service  providers  and their
            preference for owning or leasing antenna sites,

      o     the  growth  rate  of  wireless  communications  or of a  particular
            wireless segment,

      o     the number of wireless  service  providers in a particular  segment,
            nationally or locally,

      o     governmental licensing of broadcast rights,

      o     zoning, environmental and other government regulations, and

      o     technological changes.

     "Roaming" and "resale"  arrangements  could also  adversely  affect demand.
These arrangements enable a wireless service provider to serve customers outside
its license area  through  agreements  with other  providers.  Wireless  service
providers might consider roaming and resale  arrangements  preferable to leasing
antenna space from us.

                                      -12-
<PAGE>

New  tower   construction,   particularly   build-to-suit   projects,   involves
uncontrollable risks and increasing competition

     Our increasing focus on major  build-to-suit  projects for wireless service
providers entails several unique risks. The first is the greater dependence on a
single customer.  Second,  because of intense competition for these projects, we
often  grant the  wireless  service  provider  non-economic  lease  and  control
provisions more favorable than our general terms. Finally,  although we have the
benefit of an "anchor" tenant in build-to-suit  projects,  we may not be able to
find a sufficient  number of additional  tenants.  In fact, one reason  wireless
service providers may want build-to-suit  arrangements is to share or escape the
costs of an  undesirable  site.  A site may be  undesirable  because it has high
construction costs or may be considered a poor location by other providers.

     Our expanded construction  activities also involve other substantial risks.
These risks include:

      o     increasing our debt and the amount of payments on that debt,

      o     uncontrollable  risks that  could  delay or  increase  the cost of a
            project,

      o     increasing  competition for construction sites and experienced tower
            construction companies,  resulting in significantly higher costs and
            failure to meet time schedules,

      o     failing  to  meet  time   schedules   could  result  in  our  paying
            significant  penalties  to  prospective  tenants,   particularly  in
            build-to-suit situations, and

      o     possible  lack of  sufficient  experienced  personnel  to  manage an
            expanded construction program.

      We cannot control the main factors that can prevent, delay or increase the
cost of construction. These factors include:

      o     zoning and local permitting requirements,

      o     environmental group opposition,

      o     availability  of skilled  construction  personnel  and  construction
            equipment,

      o     adverse weather conditions, and

      o     federal regulations.


Our acquisition strategy involves increasing acquisition costs, high debt levels
and potential management and integration issues

     Increased  competition,  which we believe  will  continue,  has resulted in
substantially  higher acquisition  costs,  particularly for towers being sold by
wireless service providers.  These prices, in turn, result in high debt and debt
service requirements.  Equally important, the increased size of our acquisitions
from wireless service  providers could create certain problems we have not faced
in the past:

      o     dependence on a limited number of customers,

      o     lease and control  provisions more favorable to the wireless service
            provider than those we give our tenants generally,

      o     integration of major national networks into our operational systems,

                                      -13-
<PAGE>

      o     demands on managerial  personnel  that could divert their  attention
            from other aspects of our business, and

      o     potential  antitrust  constraints,  either in local  markets or on a
            regional or national basis, that could impede future acquisitions or
            require selective divestitures at unfavorable prices.

     An additional risk is the acquisition of significant numbers of towers that
may   have   limited   marketing   potential.    See   "American   Tower--Recent
Developments--Pending Transactions--AT&T transaction" under "Summary" on page 4.


Covenants in our credit facilities could impede our growth strategy and restrict
our ability to pay interest on or redeem or repurchase the notes

     Our growth strategy may be impaired by restrictive  covenants in our credit
facilities.  The  most  significant  of these  covenants  impose  limits  on our
aggregate  borrowings and require us to meet certain financial ratios and comply
with all of the  financial and other  covenants in order to borrow funds.  Also,
certain types of acquisitions  and investments in other companies are limited in
accordance with a formula based,  in part, on proceeds of equity  offerings and,
in part, on cash flow.  Events beyond our control may affect our ability to meet
these requirements. If these covenants restrict our ability to borrow funds, our
acquisition strategy and construction program will be harmed.

     Our credit  facilities also restrict the ability of our subsidiaries to pay
dividends or make other  distributions  to the parent company and prohibit those
dividends  and other  distributions  during  periods of default.  Since we are a
holding  company,  with  no  independent  operations,  we are  dependent  on our
subsidiaries  for  funds  in  order  for us to make  payments  of  interest  and
principal on the notes.

     In addition,  our existing credit facilities  prohibit us from redeeming or
repurchasing  any of the notes without bank consent until  December  2006.  This
requires us to elect to  repurchase  the notes with Class A common  stock on the
repurchase  dates and to obtain bank consent in order to  repurchase  notes upon
any change in control.

     Our new credit facilities,  if entered into, may contain different and more
restrictive  covenants  than our  existing  credit  facilities  with  respect to
payments  of interest  on and  principal  of the notes and on the ability of our
subsidiaries  to pay  dividends or make other  distributions  and our ability to
make certain types of acquisitions and investments.


Our future commitments for pending  transactions  exceed our currently available
funds

     We have the  ability  to  borrow  approximately  $483.0  million  under our
existing credit facilities.  We also had, as of October 15, 1999, available cash
of $154.0 million. Our future commitments under pending  transactions  aggregate
$1.7 billion.  Accordingly,  we must arrange for additional  borrowings or other
external  funds in order to complete  all or some of our  pending  transactions.
There is no assurance that we will successfully  negotiate new credit facilities
or that we will  obtain our  desired new  borrowing  level.  If we are unable to
complete transactions that we are contractually bound to perform, we may have to
pay liquidated or other damages to the other parties to the agreements. Pursuant
to our agreement with AirTouch,  we paid a deposit of $100.0  million,  which we
could forfeit if we were unable to close the transaction.

Interest on the notes may not be deductible

     If the notes  were  found to be  "corporate  acquisition  indebtedness"  or
"disqualified debt instruments," we would not be entitled to deduct the interest
on the notes for federal  income tax purposes.  See "Certain  Federal Income Tax
Consequences--Our Deductions for Interest and OID on the Notes" on page 48.

                                      -14
<PAGE>

We are dependent on key personnel and would be adversely affected if they leave

     The loss of our  Chief  Executive  Officer,  Steven  B.  Dodge,  and  other
executive  officers has a greater likelihood of having a material adverse effect
upon us than it would on most other  companies of our size. Our growth  strategy
is  highly  dependent  on the  efforts  of Mr.  Dodge  and our  other  executive
officers. Our ability to raise capital is dependent in part on the reputation of
Mr.  Dodge.  You  should  be aware  that we have  not  entered  into  employment
agreements with Mr. Dodge or most of our other executive officers. We may not be
able  to  retain  our  executive  officers,   including  those  with  employment
agreements,  or other key  personnel or prevent them from  competing  with us if
they leave.


New technologies could make our tower antenna leasing services less desirable to
potential tenants

     Mobile  satellite  systems and other new  technologies  could  compete with
land-based  wireless  communications  systems,  thereby  reducing the demand for
tower lease space and other  services  we provide.  The FCC has granted  license
applications for several low-earth  orbiting satellite systems that are intended
to provide  mobile voice or data  services.  In addition,  the  emergence of new
technologies  could reduce the need for tower-based  transmission  and reception
and have an adverse affect on our operations.  For example, at least one company
is offering  systems with devices that can be attached to telephone  and utility
lines that could serve as an alternative to certain towers.

     The growth in delivery of video services by direct broadcast satellites and
the development  and  implementation  of signal  combining  technologies,  which
permit one  antenna to  service  two  different  transmission  frequencies  and,
therefore,  two  customers,  could also reduce the demand for our tower space by
wireless service providers.


We have Year 2000 risks, including some that are unique to tower operation

     We,  like all  companies,  face  risks  associated  with the fact that many
computers  and computer  software  programs  were not designed to recognize  the
change from 1999 to 2000 or are otherwise unable to process dates related to the
turn of the millennium.  These  computers,  and the systems they control,  might
malfunction or cease to work unless they are reprogrammed or replaced by the end
of 1999.

     One  known  area of  Year  2000  risk  for us and for  other  operators  of
communications sites is tower lighting systems. Year 2000-related problems could
prevent our  monitoring  system from detecting a failure of light systems on our
tower  structures,  creating  a  situation  where a failed  light  might  not be
automatically  reported  to  air  navigation.  We and  other  tower  owners  are
responsible  for  providing  tower  lighting  that  complies  with  FCC  and FAA
requirements.  Our Year 2000  plans and risks  are more  fully  discussed  under
"Management's  Discussion  and  Analysis of Financial  Condition  and Results of
Operations--Year 2000" in the June 1999 Quarterly Report.


We  could  be  harmed  if  perceived  health  risks  from  radio  emissions  are
substantiated

     If a  connection  between  radio  emissions  and possible  negative  health
effects,  including  cancer,  were  established,  we  would  be  materially  and
adversely affected. The results of several substantial studies by the scientific
community in recent years have been inconclusive.  We and the lessees of antenna
sites on our towers are  subject to  government  regulations  relating  to radio
frequency emissions.  We do not maintain any significant  insurance with respect
to these matters.

                                      -15-
<PAGE>

Pro forma  financial  information is based on estimates and  assumptions and may
not be indicative of actual future results

     Our actual future  results could vary  materially  and adversely from those
reflected  in the pro  forma  financial  information  we have  included  in this
prospectus. That information is based upon a number of assumptions we believe to
be reasonable.  However, our two most significant acquisitions, the AirTouch and
AT&T  transactions,  do not involve the  acquisition of  businesses.  The towers
involved in those  acquisitions  were  operated as part of the wireless  service
businesses of AirTouch and AT&T.  Separate financial records were not maintained
and financial  statements were never prepared for the operation of those towers.
We have,  however,  compiled certain revenue and expense data of those towers in
the pro forma  information.  In the case of certain expenses,  we have estimated
amounts  based  on our  own  experience  with  comparable  towers.  Neither  our
auditors,  AirTouch's auditors,  AT&T's auditors nor the initial purchasers have
expressed any opinion or provided any form of assurance with respect to AirTouch
or AT&T's  historical  data  presented  in the  unaudited  pro  forma  financial
information.


We could have liability under environmental laws

     Under various federal, state and local environmental laws, we, as an owner,
lessee or operator of real estate,  may be liable for the  substantive  costs of
remediating soil and groundwater contaminated by hazardous wastes. Some of these
laws may impose  responsibility and liability on us even if we did not cause the
contamination  or even  know  about  it.  Almost  all of the  towers  we own and
operate,  other than rooftop towers, are located on parcels of land, which could
result in substantial environmental liability. Our liability often will continue
even if we sell the property.


The  notes  will  effectively  rank  junior to  secured  debt  under our  credit
facilities

     Our payment of principal of and interest on the notes will effectively rank
junior to all existing and future debt under our credit  facilities.  This is so
because  the debt under our credit  facilities  is issued or  guaranteed  by our
subsidiaries  and secured by their assets.  The notes will also effectively rank
junior to all other  existing  and future debt of our  subsidiaries.  The parent
company has also  guaranteed  that debt and secured it with its assets,  and the
stock  of its  subsidiaries.  As a  result,  in  the  event  of our  insolvency,
liquidation or reorganization, or should any of that debt be accelerated because
of a default,  we must pay that debt in full  before we can make any  payment on
the notes.


There may not be any trading market for the notes

     There  is no  existing  trading  market  for the  notes  and one may  never
develop.  Accordingly, you may not be able to sell your notes or sell them at an
acceptable  price. If a market were to develop,  the notes could trade at prices
that may be higher or lower than the initial  offering  price  depending on many
factors,  including  prevailing  interest rates, the market price of the Class A
common stock, our operating results and the market for similar  securities.  The
initial  purchasers of the notes have advised us that they  currently  intend to
make a market in the notes of each series.  They are not, however,  obligated to
do so.  Any  market  making  may be  discontinued  at any time  without  notice.
Therefore,  we cannot assure you as to the  liquidity of any trading  market for
either  series of the notes or that an active  market  for  either  series  will
develop.  We do not intend to list the notes of either series on any  securities
exchange or to seek  approval  for  quotation  through any  automated  quotation
system.


Control by our  principal  stockholders  could deter mergers where you could get
more than current market price for your stock

         Control by Mr. Dodge and others may have the effect of  discouraging  a
merger or other takeover of our company in which holders of Class A common stock
may be paid a premium for their  shares over  then-current  market  prices.  Mr.
Dodge,  together with a limited number of our directors,  may be able to control
or  block  the  vote

                                      -16-
<PAGE>

on mergers and other matters submitted to the common stockholders. On October 1,
1999,  our  directors and executive  officers,  together with their  affiliates,
owned  "beneficially"  approximately  45% of the  combined  voting  power of the
common stock.  On that date,  Mr. Dodge,  together  with his  affiliates,  owned
"beneficially" approximately 29% of the combined voting power.


Our common stock does not pay dividends

     We have never paid a dividend on our common  stock and do not expect to pay
cash dividends in the foreseeable future.


Our  forward-looking  statements  could prove to be wrong and we might  suffer a
material adverse effect

     Our forward-looking statements are subject to risks and uncertainties.  You
should note that many  factors,  some of which are  discussed in this section or
elsewhere  in  this  prospectus  or in the  documents  we have  incorporated  by
reference, could affect our company in the future and could cause our results to
differ  materially  from  those  expressed  in our  forward-looking  statements.
Forward-looking  statements include those regarding our goals, beliefs, plans or
current  expectations  and  other  statements  regarding  matters  that  are not
historical  facts.  For  example,  when we use the  words  "believe,"  "expect,"
"anticipate" or similar expressions,  we are making forward-looking  statements.
Forward-looking statements include statements concerning:

      o     the outcome of our growth strategy,

      o     future results of operations,

      o     liquidity and capital expenditures,

      o     construction and acquisition activities,

      o     debt levels and the ability to obtain financing and make payments on
            our debt,

      o     regulatory   developments   and   competitive   conditions   in  the
            communications site and wireless carrier industries,

      o     projected growth of the wireless communications and wireless carrier
            industries, and

      o     general economic conditions.

     We are not  required to release  publicly  the results of any  revisions to
these  forward-looking  statements  we may  make to  reflect  future  events  or
circumstances.

                                      -17-
<PAGE>




                        MARKET PRICES AND DIVIDEND POLICY

Market Price Data

     On February  27,  1998,  our Class A common  stock  commenced  trading on a
"when-issued" basis on the inter-dealer  bulletin board of the  over-the-counter
market.  Our Class A common stock commenced  trading on the NYSE on June 5, 1998
(the day after we separated from American Radio  Systems).  The following  table
presents  reported  high and low sale prices of our Class A common  stock in the
over-the-counter market or on the Composite Tape of the NYSE.

<TABLE>
<CAPTION>
                                   1998                                       High             Low
                                   ----                                       ----             ---
<S>                                                                       <C>                <C>
          Quarter Ended March 31 (commencing February 27, 1998).......... $   20.250         $15.500
          Quarter Ended June 30..........................................     26.125          18.750
          Quarter Ended September 30.....................................     28.625          14.375
          Quarter Ended December 31......................................     29.625          13.250


<CAPTION>
                                   1999
                                   ----
<S>                                                                       <C>                <C>
          Quarter Ended March 31.........................................     30.250          20.500
          Quarter Ended June 30..........................................     26.875          20.500
          Quarter Ended September 30.....................................     25.875          19.500
          Quarter Ended December 31 (through October 19).................     20.125         17.5625
</TABLE>

   The outstanding shares of common stock and number of registered holders as of
October 1, 1999 were as follows:


<TABLE>
<CAPTION>
                                                                                            Class
                                                                                 ----------------------------
                                                                                  A            B           C
                                                                             -----------   ---------   ---------
<S>                                                                          <C>           <C>         <C>
Outstanding shares.......................................................    144,466,550   8,811,940   2,422,804
Registered holders.......................................................            539          64           1
</TABLE>


Dividends

     We have never paid a dividend on any class of common  stock.  We anticipate
that we will retain future earnings,  if any, to fund the development and growth
of our business.  We do not anticipate paying cash dividends on shares of common
stock in the foreseeable  future. Our credit facilities  restrict the payment of
cash dividends by our subsidiaries.  See "Description of Capital Stock--Dividend
Restrictions" on page 41.

                                      -18-
<PAGE>




         UNAUDITED PRO FORMA CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

     We have  included our unaudited pro forma  condensed  consolidated  balance
sheet as of June 30, 1999 and our  unaudited  pro forma  condensed  consolidated
statements  of operations  for the year ended  December 31, 1998 and for the six
months ended June 30, 1999. To the extent  required,  these pro forma statements
have been adjusted for:

      o     the  OmniAmerica  merger,  the TeleCom  merger,  the separation from
            American Radio Systems,  the ATC merger, the Wauka transaction,  the
            UNIsite merger, the AirTouch transaction and the AT&T transaction,

      o     our  public  offerings  of  Class A common  stock  in July  1998 and
            February 1999 and our private placement in February 1999, and

      o     the notes placement in October 1999.

     The pro forma financial statements do not reflect all of our consummated or
pending  acquisitions.  The adjustments  assume that all pro forma  transactions
were  consummated  on January 1, 1998,  in the case of the  unaudited  pro forma
condensed consolidated statement of operations.  The adjustments assume that the
pending pro forma  transactions were consummated as of June 30, 1999 in the case
of the unaudited pro forma condensed consolidated balance sheet. You should read
the pro forma financial  statements in conjunction with the Historical Financial
Statements.  Although the AirTouch  transaction and the AT&T  transaction do not
involve the  acquisition of a business,  we have provided pro forma  information
related to these  transactions,  as we believe such  information  is material to
your investment decision.

     The pro forma financial  statements may not reflect our financial condition
or our results of  operations  had these  events  actually  occurred on the date
specified.  They may also not reflect our financial  condition or our results of
operations of operating as a separate,  independent  company during the periods.
Finally,  they may not  reflect  our future  financial  condition  or results of
operations.


                                      -19-
<PAGE>




<TABLE>
<CAPTION>
                           AMERICAN TOWER CORPORATION

            UNAUDITED PRO FORMA CONDENSED CONSOLIDATED BALANCE SHEET

                                  JUNE 30, 1999
                                 (in thousands)

                                                              Adjustments
                                                             for Pro Forma    Pro Forma,
                                                  Historical Transactions(a) as adjusted
                                                  ---------- --------------- -----------
                    ASSETS
<S>                                                <C>            <C>         <C>
Cash and cash equivalents.....................     $ 353,221      $  6,926    $ 360,147
Accounts receivable, net......................        38,454         2,384       40,838
Other current assets..........................        25,501           529       26,030
Notes receivable..............................        13,624                     13,624
Property and equipment, net...................       725,846                    725,846
Unallocated purchase price....................                   1,367,712    1,367,712
Intangible assets, net........................     1,213,374                  1,213,374
Deferred tax asset............................       116,079                    116,079
Deposits and other assets.....................        32,477        16,000       48,477
                                                  ----------    ----------   ----------
   Total......................................    $2,518,576    $1,393,551   $3,912,127
                                                  ==========    ==========   ==========
<CAPTION>
                LIABILITIES AND
             STOCKHOLDERS' EQUITY
<S>                                                <C>            <C>         <C>
Current liabilities, excluding current
   portion of long-term debt..................      $ 64,328      $ 12,939     $ 77,267
Deferred income taxes.........................                      45,656       45,656
Other long-term liabilities...................         2,545         1,520        4,065
Long-term debt, including current
   portion....................................       284,121       687,936      972,057
Convertible notes, net of discount............                     600,000      600,000
Minority interest.............................         5,649                      5,649
Stockholders' equity..........................     2,161,933        45,500    2,207,433
                                                  ----------    ----------   ----------
   Total.....................................     $2,518,576    $1,393,551   $3,912,127
                                                  ==========    ==========   ==========
</TABLE>

                   See Notes to Unaudited Pro Forma Condensed
                 Consolidated Balance Sheet of American Tower.


                                      -20-
<PAGE>




        NOTES TO UNAUDITED PRO FORMA CONDENSED CONSOLIDATED BALANCE SHEET

     We have  prepared the unaudited pro forma  condensed  consolidated  balance
sheet as of June 30,  1999 to give  effect,  as of such  date,  to the  AirTouch
transaction,  the AT&T transaction,  the UNIsite merger and the notes placement,
the only pro forma  transactions  not  completed  by that  date.  See  "American
Tower--Recent  Developments--Pending Transactions" under "Summary" on page 4 for
a description of those pro forma transactions.

(a) The following table sets forth the pro forma balance sheet adjustments as of
June 30, 1999 (in thousands).

<TABLE>
<CAPTION>
                                                                                                                       Total
                                                                                                                    Adjustments
                                                                  AirTouch       AT&T      UNIsite      Notes      for Pro Forma
                                                                 Transaction  Transaction  Merger     Placement     Transactions
                                                                 -----------  -----------  ------     ---------     ------------
                            ASSETS
<S>                                                               <C>            <C>        <C>         <C>          <C>
Cash and cash equivalents.....................................                              $  6,926                 $    6,926
Accounts receivable, net......................................                                 2,384                      2,384
Other current assets..........................................                                   529                        529
Unallocated purchase price(1).................................    $845,500       $265,000    257,212                  1,367,712
Deposits and other assets.....................................                                           $ 16,000        16,000
                                                                  --------       --------   --------     --------    ----------
   Total......................................................    $845,500       $265,000   $267,051     $ 16,000    $1,393,551
                                                                  ========       ========   ========     ========    ==========
<CAPTION>
             LIABILITIES AND STOCKHOLDERS' EQUITY
<S>                                                               <C>            <C>        <C>         <C>          <C>
Current liabilities, excluding current portion of long-term
   debt.......................................................                   $  5,000   $  7,939                 $   12,939
Deferred income taxes.........................................                                45,656                     45,656
Other long-term liabilities...................................                                 1,520                      1,520
Long-term debt, including current portion.....................    $800,000        260,000    211,936    $(584,000)      687,936
Convertible notes, net of discount............................                                            600,000       600,000
Stockholders' equity..........................................      45,500(2)                                            45,500
                                                                  --------       --------   --------     --------    ----------
   Total......................................................    $845,500       $265,000   $267,051     $ 16,000    $1,393,551
                                                                  ========       ========   ========     ========    ==========
</TABLE>

     We will  account for all of the pro forma  transactions  under the purchase
method of accounting.

     The  following  table sets forth the purchase  prices and related pro forma
financing of the transactions described above (in millions).

<TABLE>
<CAPTION>
                                                                                                    Fair Value of
                                                                        Purchase Price   Borrowings  Debt Assumed
<S>                                                                          <C>             <C>
AirTouch transaction..................................................       $ 845.5(1)      $ 800.0
AT&T transaction......................................................         260.0           260.0
UNIsite merger........................................................         165.0           160.2    $  51.7
</TABLE>


(1)   Upon  completion of our evaluation of the purchase price  allocations,  we
      expect that the average life of the assets should approximate 15 years.
(2)   We have  agreed to issue  warrants  having a fair  value of  approximately
      $45.5  million to purchase an  aggregate  of  3,000,000  shares of Class A
      common stock at $22.00 per share.



                                      -21-
<PAGE>

<TABLE>
<CAPTION>
                                            AMERICAN TOWER CORPORATION

                        UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS

                                           Year Ended December 31, 1998
                                       (in thousands, except per share data)

                                                              Adjustments
                                                             for Pro Forma    Pro Forma,
                                                 Historical  Transactions(a)  as adjusted
                                                 ----------  ---------------  -----------
<S>                                               <C>            <C>          <C>
Operating revenues............................    $ 103,544      $  169,548   $ 273,092
Operating expenses excluding depreciation
   and amortization, tower separation, and
   corporate general and administrative
   expenses...................................       61,751         110,873     172,624
Depreciation and amortization.................       52,064         160,795     212,859
Tower separation expenses.....................       12,772                      12,772
Corporate general and administrative
   expenses...................................        5,099           3,500       8,599
                                                  ---------      ----------   ---------
Loss from operations..........................      (28,142)       (105,620)   (133,762)
                                                  ---------      ----------   ---------
Other (income) expense:
   Interest expense...........................       23,229          91,592     114,821
   Interest income and other, net.............       (9,217)                     (9,217)
   Minority interest in net earnings of
   subsidiaries...............................          287                         287
                                                  ---------      ----------   ---------

Total other (income) expense..................       14,299          91,592     105,891
                                                  ---------      ----------   ---------
(Loss) income before income taxes and
   extraordinary losses.......................      (42,441)       (197,212)   (239,653)
(Benefit) provision for income taxes(b).......       (4,491)        (65,600)    (70,091)
                                                  ---------      ----------   ---------
(Loss) income before extraordinary losses.....    $ (37,950)     $ (131,612)  $(169,562)
                                                  =========      ==========   =========
Basic and diluted (loss) per common share
   before extraordinary losses................    $   (0.48)         N/A      $   (1.10)
                                                  =========      ==========   =========
Basic and diluted common shares
   outstanding(c).............................       79,786          74,872     154,658
                                                  =========      ==========   =========
</TABLE>


                   See Notes to Unaudited Pro Forma Condensed
                     Consolidated Statement of Operations.


                                      -22-
<PAGE>


                          NOTES TO UNAUDITED PRO FORMA
                 CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS

     The unaudited pro forma condensed  consolidated statement of operations for
the year ended December 31, 1998 gives effect to the pro forma transactions,  as
if each of them had  occurred on January 1, 1998.  See  "American  Tower--Recent
Developments--Pending  Transactions" under "Summary" on page 4 for a description
of the pending pro forma transactions and Historical  Financial Statements for a
description of the other pro forma transactions.

     (a) To record the results of operations for the pro forma transactions.  We
have  adjusted the results of  operations  to: (1) reverse  historical  interest
expense; and (2) record an increase of net interest expense of $99.0 million for
the year ended  December 31, 1998 as a result of the increased debt after giving
effect  to the July  1998 and  February  1999  equity  financings  and the notes
placement.

     We have also  adjusted  the  results of  operations  to reverse  historical
depreciation  and  amortization  expense  of $20.3  million  for the year  ended
December 31, 1998 and record  depreciation  and  amortization  expense of $160.8
million for the year ended  December 31, 1998 based on estimated  allocations of
purchase prices. With respect to unallocated  purchase price, we have determined
pro forma  depreciation  and  amortization  expense based on an expected average
life of 15 years. Debt discount is being amortized using the effective  interest
method.  Debt issuance  costs are being  amortized on a straight line basis over
the term of the  obligations.  Amortization  of debt discount and issuance costs
are included within interest expense.

     We have not carried forward corporate general and  administrative  expenses
of the  prior  owners  into  the  pro  forma  condensed  consolidated  financial
statements.  These costs represent  duplicative  facilities and  compensation to
owners and/or  executives we did not retain,  including  charges  related to the
accelerated vesting of stock options and bonuses that were directly attributable
to the  purchase  transactions.  Because we already  maintain  our own  separate
corporate  headquarters,  which provides services substantially similar to those
represented  by  these  costs,  we do not  expect  them to recur  following  the
acquisition.  After giving  effect to an estimated  $3.5 million of  incremental
costs,  we believe  that we have  existing  management  capacity  sufficient  to
provide the services without incurring additional incremental costs.


                                      -23-
<PAGE>

     The following table sets forth the historical results of operations for the
pro forma transactions for the year ended December 31, 1998 (in thousands).

<TABLE>
<CAPTION>
                                Wauka        ATC    Separation     July     OmniAmerica    TeleCom    February
                             Transaction   Merger    From ARS    Offering      Merger       Merger    Offerings
                             -----------   ------   ----------   --------   -----------    -------    ---------
<S>                              <C>       <C>        <C>         <C>           <C>         <C>        <C>
Operating revenues..........     $ 4,736    $11,337                             $ 82,313    $ 12,273
Operating expenses
   excluding depreciation
   and amortization, and
   corporate general and
   administrative expenses.        2,065      3,936                               73,461       2,701
Depreciation and
   amortization.............         986      3,125                                8,325       5,990
Corporate general and
   administrative expenses.        3,520                                                      13,932
                                 -------   --------                             --------    --------
(Loss) income from
   operations...............      (1,835)     4,276                                  527     (10,350)
Other (income) expense:
   Interest expense.........         997      3,333     $8,901    $(15,736)        2,638       2,873   $(19,184)
   Interest income..........                                                                    (660)
   Other, net...............           9      5,144                                 (458)        843
                                 -------   --------   --------    --------      --------    --------   --------

(Loss) income before
   income taxes.............     $(2,841)  $ (4,201)  $ (8,901)   $ 15,736      $ (1,653)   $(13,406)  $ 19,184
                                 =======   ========   ========    ========      ========    ========   ========

<CAPTION>
                                                                                        Total Adjustments
                               UNIsite     AirTouch      AT&T      Notes     Pro Forma    for Pro Forma
                                Merger   Transaction Transaction Placement  Adjustments    Transactions
                                ------   ----------- ----------- ---------  -----------    ------------
<S>                             <C>       <C>        <C>            <C>       <C>         <C>
Operating revenues...........    $ 4,414   $51,566(d)  $ 2,909(e)                         $ 169,548
Operating expenses
   excluding depreciation
   and amortization, and
   corporate general and
   administrative expenses...      1,615    19,400(f)    7,695(f)                           110,873
Depreciation and
   amortization..............      1,870                                      $ 140,499     160,795
Corporate general and
   administrative expenses...     12,273                                        (26,225)      3,500
                                --------  --------   ---------                ---------   ---------
(Loss) income from
   operations................    (11,344)   32,166      (4,786)                (114,274)   (105,620)
Other (income) expense:
   Interest expense..........      6,320    64,000      20,800      $(7,403)     24,053      91,592
   Interest income...........     (2,331)                                         2,991
   Other, net................        (27)                                        (5,511)
                                --------  --------   ---------      -------   ---------   ---------
(Loss) income before
   income taxes..............   $(15,306) $(31,834)  $ (25,586)     $ 7,403   $(135,807)  $(197,212)
                                ========  ========   =========      =======   =========   =========
</TABLE>

      (b) To record  the tax effect of the pro forma  adjustments  and impact on
our estimated effective tax rate. The actual effective tax rate may be different
once we determine the final allocation of purchase price.

      (c) Includes  shares of Class A common stock issued pursuant to: the Wauka
transaction--1.4   million,  the  ATC  Merger--28.8   million,  the  OmniAmerica
merger--16.8  million,  the TeleCom  merger--3.9  million,  July  offering--27.9
million, and the February offerings--26.2 million.

                                      -24-
<PAGE>

      (d) Includes  additional  revenues to be recognized in connection with the
AirTouch lease  agreement.  Approximately  $3.5 million of existing  third-party
lease revenues has not been included.

      (e) Includes  additional  revenues to be recognized in connection with the
AT&T and AT&T Wireless Services lease agreements.  Approximately $8.8 million of
existing third-party lease revenues has not been included.

      (f) The towers  involved in each of these  acquisitions  were  operated as
part of the  wireless  service  businesses  of AirTouch  and AT&T.  Accordingly,
separate  financial  records were not maintained and financial  statements  were
never  prepared for the  operation of these  towers.  In addition to land leases
that we will  assume,  we have  estimated  certain  operating  expenses we would
expect  to incur  based  on our own  experience  with  comparable  towers.  Such
estimates  include  expenses  related to  utilities,  repairs  and  maintenance,
insurance  and  real  estate  taxes.  These  operating  expenses  are  based  on
management's  best estimate and, as such,  the actual  expenses may be different
than the estimate presented.


                                      -25-
<PAGE>

<TABLE>
<CAPTION>
                                            AMERICAN TOWER CORPORATION

                        UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS

                                          Six Months Ended June 30, 1999
                                       (in thousands, except per share data)

                                                              Adjustments
                                                             for Pro Forma   Pro Forma,
                                                 Historical  Transactions(a) as adjusted
                                                 ----------  --------------- -----------
<S>                                               <C>             <C>        <C>
Operating revenues............................     $101,561         $44,921   $146,482
Operating expenses excluding depreciation
   and amortization and corporate, general
   and administrative expenses................       59,020          29,027     88,047
Depreciation and amortization.................       57,808          53,824    111,632
Corporate general and administrative
   expenses...................................        4,140           1,750      5,890
                                                  ---------       ---------  ---------
Loss from operations..........................      (19,407)        (39,680)   (59,087)
                                                  ---------       ---------  ---------
Other (income) expense:
   Interest expense...........................       11,539          48,020     59,559
   Interest income and other, net.............      (10,737)                   (10,737)
   Minority interest in net losses of
     subsidiaries.............................          (79)                       (79)
                                                  ---------       ---------  ---------
Total other (income) expense..................          723          48,020     48,743
                                                  ---------       ---------  ---------
(Loss) income before income taxes and
   extraordinary loss.........................      (20,130)        (87,700)  (107,830)
(Benefit) provision for income taxes(b).......         (747)        (30,788)   (31,535)
                                                  ---------       ---------  ---------
(Loss) income before extraordinary loss.......    $ (19,383)      $ (56,912) $ (76,295)
                                                  =========       =========  =========
Basic and diluted (loss) per common share
   before extraordinary loss..................      $ (0.14)         N/A       $ (0.49)
                                                  =========       =========  =========
Basic and diluted common shares
   outstanding(c).............................      143,503          12,016    155,519
                                                  =========       =========  =========
</TABLE>







                   See Notes to Unaudited Pro Forma Condensed
                     Consolidated Statement of Operations.



                                      -26-
<PAGE>

   NOTES TO UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS

     The unaudited pro forma condensed  consolidated statement of operations for
the six months  ended June 30, 1999 gives  effect to the pro forma  transactions
not   consummated   as  of  January  1,  1999.   See   "American   Tower--Recent
Developments--Pending  Transactions" under "Summary" on page 4 for a description
of the pending pro forma  transactions and the Historical  Financial  Statements
for a description of the other pro forma transactions.

     (a) To record the results of operations for the pro forma transactions.  We
have  adjusted the results of  operations  to: (1) reverse  historical  interest
expense; and (2) record an increase in net interest expense of $51.7 million for
the six  months  ended  June 30,  1999 as a result of the  increased  debt after
giving  effect to the proceeds of the February  1999 equity  financings  and the
notes placement.

     We have also  adjusted  the  results of  operations  to reverse  historical
depreciation and  amortization  expense of $5.4 million for the six months ended
June 30, 1999 and record depreciation and amortization  expense of $53.8 million
for the six  months  ended  June 30,  1999  based on  estimated  allocations  of
purchase prices. With respect to unallocated  purchase price, we have determined
pro forma  depreciation  and  amortization  expense based on an expected average
life of 15 years. Debt discount is being amortized using the effective  interest
method.  Debt issuance  costs are being  amortized on a straight line basis over
the term of the obligation. Amortization of debt discount and issuance costs are
included within interest expense.

     We have not carried forward corporate general and  administrative  expenses
of the  prior  owners  into  the  pro  forma  condensed  consolidated  financial
statements.  These costs represent  duplicative  facilities and  compensation to
owners and/or  executives we did not retain,  including  charges  related to the
accelerated vesting of stock options and bonuses that were directly attributable
to the  purchase  transactions.  Because we already  maintain  our own  separate
corporate  headquarters,  which provides services substantially similar to those
represented  by  these  costs,  we do not  expect  them to recur  following  the
acquisition.  After giving  effect to an estimated  $1.8 million of  incremental
costs,  we believe  that we have  existing  management  capacity  sufficient  to
provide the services without incurring additional incremental costs.

     The following table sets forth the historical results of operations for the
pro forma transactions for the six months ended June 30, 1999 (in thousands).

<TABLE>
<CAPTION>
                                                                                                                        Total
                                                                                                                       Adjustments
                             OmniAmerica  TeleCom  February  UNIsite   AirTouch      AT&T       Notes     Pro Forma   for Pro Forma
                               Merger     Merger   Offerings  Merger Transaction Transaction  Placement  Adjustments  Transactions
                               ------     ------   ---------  ------ ----------- -----------  ---------  -----------  ------------
<S>                             <C>      <C>         <C>     <C>       <C>         <C>           <C>       <C>        <C>
Operating revenues.........     $ 12,246  $ 2,029            $ 3,408   $25,783(d)  $ 1,455(e)                         $ 44,921
Operating expenses excluding
   depreciation and
   amortization, and
   corporate general and
   administrative expenses.       12,257      549              2,673     9,700(f)    3,848(f)                           29,027
Depreciation and
   amortization............        2,372    1,201              1,871                                         $48,380    53,824
Corporate general and
   administrative expenses.        2,882   10,173              5,148                                         (16,453)    1,750
                                -------- --------            -------   -------     -------                 ---------  --------
(Loss) income from
   operations..............       (5,265)  (9,894)            (6,284)   16,083      (2,393)                  (31,927)  (39,680)
Other (income) expense:
   Interest expense, net...          746      521    $(1,499)  3,558                            $ (3,671)     48,365    48,020
   Interest income.........          (14)                       (361)                                            375
   Other, net..............          816     (106)               381                                          (1,091)
                                -------- --------    ------- -------   -------     -------       -------   ---------  --------
(Loss) income before
   income taxes............     $ (6,813)$(10,309)   $ 1,499 $(9,862)  $16,083     $(2,393)      $ 3,671   $ (79,576) $(87,700)
                                ======== ========    ======= =======   =======     =======       =======   =========  ========
</TABLE>


      (b) To record  the tax effect of the pro forma  adjustments  and impact on
our estimated effective tax rate. The actual effective tax rate may be different
once we determine the final allocation of purchase price.



                                      -27-
<PAGE>

      (c)  Includes  shares of Class A common  stock  issued  pursuant  to:  the
OmniAmerica  merger--16.8  million,  the TeleCom  merger--3.9  million,  and the
February offerings--26.2 million.

      (d) Includes  additional  revenues to be recognized in connection with the
AirTouch lease  agreement.  Approximately  $1.7 million of existing  third-party
lease revenues has not been included.

      (e) Includes  additional  revenues to be recognized in connection with the
AT&T and AT&T Wireless Services lease agreements.  Approximately $4.4 million of
existing third-party lease revenues has not been included.

      (f) The towers  involved in each of these  acquisitions  were  operated as
part of the  wireless  service  businesses  of AirTouch  and AT&T.  Accordingly,
separate  financial  records were not maintained and financial  statements  were
never  prepared for the  operation of these  towers.  In addition to land leases
that we will  assume,  we have  estimated  certain  operating  expenses we would
expect  to incur  based  on our own  experience  with  comparable  towers.  Such
estimates  include  expenses  related to  utilities,  repairs  and  maintenance,
insurance  and  real  estate  taxes.  These  operating  expenses  are  based  on
management's  best estimate and, as such,  the actual  expenses may be different
than the estimate presented.


                                      -28-
<PAGE>

                            DESCRIPTION OF THE NOTES

         The notes have been issued under two separate indentures, each dated as
of  October  4,  1999,  between  us and The Bank of New York,  as  trustee.  The
following  statements  are subject to the detailed  provisions of the indentures
and are qualified in their  entirety by reference to the  indentures,  copies of
which have been filed as exhibits to the  registration  statement  of which this
prospectus  is a part.  Wherever  particular  provisions of the  indentures  are
referred to, those  provisions  are  incorporated  by reference as a part of the
statements  made,  and the  statements  are qualified in their  entirety by that
reference.  Certain  terms that are defined in the  indentures  are used in this
section without definitions.


General

         The notes represent our unsecured general obligations  convertible into
Class A common stock as described under  "Conversion."  The principal  amount of
the 6.25%  notes is  $300,000,000.  The  principal  amount of the 2.25% notes is
$425,500,000,  which is  equivalent  to total  proceeds  at the  issue  price of
$300,062,600.  Notes may be in fully  registered form only in  denominations  of
$1,000 or any multiple thereof.  The notes mature on October 15, 2009, unless we
redeem them or you convert them earlier.

         The  indentures  do not  contain  any  restrictions  on the  payment of
dividends,  the incurrence of debt or the repurchase of our equity securities or
any financial covenants.

         The two series of notes bear  interest at the  respective  annual rates
set forth on the cover page of this prospectus  from their issue date.  Interest
is payable  semiannually on April 15 and October 15 of each year,  commencing on
April 15, 2000,  to holders of record at the close of business on the  preceding
March 31 and September 30. We may pay interest by mailing a check to holders.

         We will make payment of principal and any premium,  and you may present
the notes for conversion, registration of transfer and exchange, without service
charge, at the office of our paying agent,  initially the trustee,  in New York,
and at the corporate trust office of the trustee in New York.

         The 2.25%  notes  were  issued at 70.52% or their  principal  amount at
maturity.  The federal  income tax  consequences  of this discount are discussed
under  "Certain  Federal  Income  Tax  Consequences--Tax  Consequences  for U.S.
Holders--Original  Issue Discount on the 2.25% Notes" on page 44. Original issue
discount  means the  difference  between  the issue price of the 2.25% notes and
their principal  amount at maturity.  The calculation of the accrual of original
issue discount in the period during which a 2.25% note remains  outstanding will
be on a  semi-annual  bond  equivalent  basis,  using a 360-day year composed of
twelve 30-day months.  The accrual will begin on October 4, 1999, the first date
of issuance of 2.25% notes.


Conversion

         You will be entitled to convert your notes, in  denominations of $1,000
principal amount at maturity or multiples  thereof,  at any time, into shares of
Class A common stock. You determine the number of shares of Class A common stock
issuable upon  conversion  by dividing the issue price of the notes  surrendered
for conversion by the  conversion  price.  The conversion  price is shown on the
cover of this prospectus.

         Upon conversion,  you will not be entitled to any payment or adjustment
on account of accrued  and unpaid  interest on notes or accrued  original  issue
discount on 2.25%  notes.  Our  delivery to you of the fixed number of shares of
Class A common stock into which the note is convertible,  together with any cash
payment in lieu of any fractional share of Class A common stock,  will be deemed
to satisfy  all of our  obligations  to pay the  principal  amount  and  accrued
interest on notes and accrued original issue discount on 2.25% notes.  Thus, the
accrued  interest and accrued  original  issue discount are deemed to be paid in
full rather than canceled, extinguished or forfeited.



                                      -29-
<PAGE>

         With  respect  to notes that have been  acquired, all shares of Class A
common stock  distributed  upon conversion will be freely  transferable  without
restriction under the Securities Act, other than by our affiliates. Those shares
will be  eligible  for  receipt on global form  through  the  facilities  of the
Depositary.

         If you  surrender  notes for  conversion  during the  period  after any
interest record date and prior to the  corresponding  interest payment date, you
must pay us the interest  payable on those  notes,  unless they have been called
for  redemption on a redemption  date on or prior to the interest  payment date.
You may not convert notes called for  redemption  after the close of business on
the business day preceding the date fixed for  redemption,  unless we default in
payment of the redemption  price. We will not issue fractional shares of Class A
common  stock on a  conversion.  Rather,  we will pay the  converting  holder an
amount of cash equal to the fair market value of the fractional interest, unless
payment in cash is  prohibited by our  indebtedness.  In that case we will issue
fractional shares.

         The  initial  conversion  price  per  share of Class A common  stock is
subject to adjustment in certain  events,  including  upon the  occurrence of an
adjustment event. We use the term "adjustment event" to mean the following:

         o  the issuance of Class A common  stock as a dividend or  distribution
            on Class A common stock,

         o  certain subdivisions and combinations of the Class A common stock,

         o  the  issuance  to all  holders  of Class A common  stock of  certain
            rights or warrants to purchase Class A common stock, and

         o  the distribution to all holders of Class A common stock of shares of
            our capital stock,  evidences of our  indebtedness  or other assets,
            including  securities.  Excluded  from the  foregoing  are shares of
            Class  A  common   stock  and  rights,   warrants,   dividends   and
            distributions  referred to above and dividends and  distributions in
            connection with our liquidation or paid in cash.

To the extent permitted by law, we may reduce the conversion price by any amount
for any  period of at least 20 days if our board of  directors  determines  that
such reduction would be in our best interests. We may also reduce the conversion
price as our board of directors  deems advisable to avoid or diminish any income
tax to  holders  of  Class  A  common  stock  resulting  from  any  dividend  or
distribution  of stock, or rights to acquire stock, or from any event treated as
such for income tax purposes.  See "Certain Federal Income Tax Consequences--Tax
Consequences for U.S. Holders--Potential Distributions Resulting from Adjustment
of Conversion Price" on page 46.

         If a  reorganization  event  occurs,  pursuant  to which any holders of
Class A common  stock  shall be entitled to receive  other  securities,  cash or
other property,  then we shall make appropriate  provision so that you will have
the right to convert notes only into the kind and amount of the securities, cash
or  other  property  you  would  have  received  had you  converted  your  notes
immediately prior to the reorganization  event. We use the term  "reorganization
event" to mean the following:

         o  any recapitalization or reclassification of shares of Class A common
            stock,  other than changes  involving par value, or as a result of a
            subdivision or combination of the Class A common stock,

         o  any  consolidation or merger  involving our company,  other than one
            that does not result in a reclassification,  conversion, exchange or
            cancellation of Class A common stock,

         o  any sale or transfer of all or substantially all of our assets, or

         o  any compulsory share exchange pursuant to which any holders of Class
            A common stock shall be entitled to receive other  securities,  cash
            or other property.



                                      -30-
<PAGE>

     Any company that  succeeds to us or acquires our assets will be required to
provide in its governing  documents the foregoing  right and also to provide for
other rights  essentially  equivalent to those described under this "Conversion"
heading.


Payment of Excess Cash Dividends

     If we declare and pay excess cash  dividends  on the Class A common  stock,
then we will pay to you an amount  equal to the  excess,  based on the number of
shares of Class A common stock that you would have  received  had you  converted
all of your notes, unless you convert and receive those dividends as a holder of
Class A common  stock.  We use the term  "excess  cash  dividends"  to mean cash
dividends in an annualized  amount per share that exceeds the greater of (a) the
annualized  amount per share of the  immediately  preceding cash dividend on the
Class A common stock,  appropriately adjusted for anti-dilution type events, and
(b) 15% of the last sale price of the Class A common stock as of the trading day
immediately  preceding  the date of  declaration  of that  dividend.  Our credit
facilities  currently  restrict us from paying cash  dividends or making  excess
cash dividend payments on the notes.


Change in Control

     If we  experience  a change  in  control,  then you will  have the right to
require us to repurchase for cash all or a portion of your notes. The repurchase
price of the 6.25%  notes is equal to the  principal  amount of the notes,  plus
accrued  and unpaid  interest,  through  the day prior to  repurchase.  The cash
repurchase  price of the 2.25% notes is their accreted  value,  plus accrued and
unpaid interest,  through the day prior to repurchase.  The repurchase day is 45
days after notice to you. By accreted value we mean the issue price of the 2.25%
notes  plus  accrued  original  issue  discount.  This  right to  require  us to
repurchase  the notes will exist  upon the  occurrence  of any change in control
whether or not the relevant transaction has been approved by our management.  It
may not be  waived  by our  management.  Your  exercise  of this  right  will be
irrevocable. We currently must obtain bank approval under our credit facilities,
which  approval may not be  forthcoming,  in order to make any change in control
payments before December 2006.

     Your right to require us to  repurchase  the notes upon a change in control
will not apply if either:

     o    the last sale  price of the  Class A common  stock for five of the ten
          trading  days  before  the date of the  change  in  control  equals or
          exceeds 105% of the applicable conversion price; or

     o    the  consideration  paid for the Class A common stock in a transaction
          constituting the change in control  consists of cash,  securities that
          are traded on a national securities exchange or quoted on the National
          Association of Securities Dealers,  Inc. Automated Quotation System or
          the  Nasdaq  National  Market,  or a  combination  of  cash  and  such
          securities,  and the aggregate fair market value of such consideration
          is a least 105% of the conversion price in effect  immediately  before
          the closing of that transaction.

     The  existence  of the right to require us to  repurchase  the notes upon a
change in control may deter certain  mergers,  tender  offers or other  takeover
attempts and may thereby adversely affect the market price of the Class A common
stock.

     By a "change in control" we mean:

     o    any person or group, other than a permitted owner,  acquires direct or
          indirect   beneficial   ownership  of  shares  of  our  capital  stock
          sufficient  to entitle  such person to  exercise  more than 50% of the
          total  voting  power of all classes of our capital  stock  entitled to
          vote generally in elections of directors;  an acquisition  could occur
          by  means  of  an   exchange   offer,   liquidation,   tender   offer,
          consolidation, merger, combination, reclassification, recapitalization
          or otherwise, or



                                      -31-
<PAGE>

     o    we sell, lease,  exchange or otherwise transfer, in one transaction or
          a series of  related  transactions,  all or  substantially  all of our
          assets to any person or group, other than to a permitted owner.

However,  a transaction  of a type  described  above that results in the Class A
common stock no longer being listed on a stock  exchange or traded on the Nasdaq
National Market would also be treated as a change in control even if a permitted
owner were involved.

     We  use  a  "permitted  owner"  to  mean  one  or  more  of  our  principal
stockholders  or any person  employed by us in a  management  capacity as of the
original  offering of the notes,  or any group of which any of them is a member.
We use the  terms  "person"  and  "group"  as those  terms  are used in  Section
13(d)(3) or 14(d)(2) of the  Exchange  Act.  Our  "principal  stockholders"  are
Steven B. Dodge, Thomas H. Stoner,  Hicks, Muse, Tate & Furst Incorporated,  Cox
Telecom Towers, Inc. and Clear Channel  Communications,  Inc. and includes their
affiliates.


Optional Redemption

     6.25% notes. We may not redeem 6.25% notes on or prior to October 22, 2002.
After October 22, 2002, at our option, we may redeem 6.25% notes, in whole or in
part,  at the  following  redemption  prices,  expressed as a percentage  of the
principal  amount.  We are also required to pay any accrued and unpaid  interest
upon redemption.

         Twelve Months (or shorter period) Commencing         Redemption Price
         --------------------------------------------         ----------------
         October 15, 2002...................................  103.125%
         October 15, 2003...................................  102.083
         October 15, 2004...................................  101.042
         October 15, 2005 and thereafter....................  100.000

     2.25% notes. We may not redeem 2.25% notes on or prior to October 22, 2003.
After October 22, 2003, at our option, we may redeem 2.25% notes, in whole or in
part,  at the  applicable  redemption  price.  The table below shows  redemption
prices of notes per $1,000  principal amount at maturity at October 22, 2003, at
October  15,  2004,  at each  following  October  15 prior to  maturity,  and at
maturity on October 15,  2009.  The prices  reflect the accrued  original  issue
discount  calculated  through each date.  The  redemption  price of a 2.25% note
redeemed between these dates would include an additional  amount  reflecting the
additional  original issue discount accrued since the next preceding date in the
table to the actual redemption date.

<TABLE>
<CAPTION>
                                                                                     (2)               (3)
                                                                (1)            Original Issue   Redemption Price
Redemption Date                                           Note Issue Price        Discount           (1)+(2)
- ---------------                                           ----------------        --------           -------
<S>                                                            <C>                 <C>               <C>
October 22, 2003..................................            $705.20              $97.73             $802.93
October 15, 2004..................................             705.20              125.28              830.48
October 15, 2005..................................             705.20              155.14              860.34
October 15, 2006..................................             705.20              186.90              892.10
October 15, 2007..................................             705.20              220.68              925.88
October 15, 2008..................................             705.20              256.60              961.80
October 15, 2009 (maturity).......................             705.20              294.80            1,000.00
</TABLE>

     General.  We must give  holders  at least 20 and not more than 60  calendar
days' notice of the redemption date.


Repurchase of Notes at the Option of the Holder

     6.25% notes.  On October 22, 2006,  we will be required to  repurchase,  at
your option,  any outstanding  6.25% note if certain  conditions are met. If you
desire us to repurchase  your 6.25% notes,  you must give,  and not withdraw,  a
written  repurchase  notice  to the  trustee  at any time  from the  opening  of
business  on the date that is 20  business  days prior to October 22, 2006 until
the close of business on October 22, 2006. The repurchase  price of a


                                      -32-
<PAGE>

6.25% note will be equal to its  principal  amount  together  with  accrued  and
unpaid interest through the repurchase date.

     2.25% notes.  On October 22, 2003,  we will be required to  repurchase,  at
your option,  any outstanding  2.25% note if certain  conditions are met. If you
desire us to repurchase  your 2.25% notes,  you must give,  and not withdraw,  a
written  repurchase  notice  to the  trustee  at any time  from the  opening  of
business  on the date that is 20  business  days prior to October 22, 2003 until
the close of business on October 22, 2003. The repurchase  price of a 2.25% note
will be equal to $802.93,  which is its accreted  value on October 22, 2003,  in
other words, its issue price plus accrued original issue discount, together with
accrued and unpaid interest through the repurchase date.

     General.  We may, at our option,  elect to pay the repurchase price in cash
or shares of Class A common stock, or any combination thereof.

     We will be required to give notice on a date not less than 20 business days
prior to the relevant repurchase date to you stating, among other things:

     o    what portion of the notes we will repurchase for cash and what portion
          for Class A common stock,

     o    if we elect to use Class A common  stock,  how we calculate its value,
          and

     o    the  procedures  that you must follow to require us to purchase  notes
          from you.

     If you elect to require us to purchase notes,  the repurchase  notice given
by you shall state:

     o    the notes to be delivered by you for purchase by us,

     o    the  portion  of the  principal  amount  at  maturity  of  notes to be
          purchased; this portion must be $1,000 principal amount at maturity or
          an integral multiple of $1,000,

     o    that the notes are to be  purchased  by us pursuant to the  applicable
          provisions of the notes, and

     o    in the event we elect to pay any  portion of the  repurchase  price in
          Class A common stock but the repurchase price is ultimately to be paid
          entirely in cash because the  conditions  to payment of any portion of
          the  repurchase  price  in  Class A common  stock  are not  satisfied,
          whether you elect:  (1) to withdraw your repurchase  notice as to some
          or all of the notes,  stating the  principal  amount at  maturity  and
          certificate  numbers of the notes as to which such withdrawal relates,
          or (2) to receive cash in respect of all or the applicable  portion of
          the repurchase price.

     If you fail to indicate in the repurchase  notice and in any written notice
of withdrawal your choice with respect to your election,  you shall be deemed to
have elected to receive cash in respect of the entire repurchase price.

     You may withdraw any  repurchase  notice by a written  notice of withdrawal
delivered to the applicable  trustee prior to 10:00 a.m. on the repurchase date.
The notice of withdrawal  must state the principal  amount at maturity,  and the
certificate  numbers of the notes as to which the withdrawal  notice relates and
the  principal  amount  at  maturity,  if  any,  which  remains  subject  to the
repurchase notice.

     If we elect to pay any portion of the repurchase price in shares of Class A
common stock,  we will determine the number of shares of Class A common stock to
be delivered by dividing  that portion by the Market Price of a share of Class A
common stock.  Our credit  facilities  require us to make the entire  payment in
Class A common stock.

     By "Market Price" we mean, in effect, the average of the Sale Prices of the
Class A common  stock  for the five  Trading  Day  period  ending  on the  third
business day prior to the applicable repurchase date,  appropriately adjusted


                                      -33-
<PAGE>

to take into account the  occurrence  of certain  events that would result in an
adjustment of the conversion price with respect to the Class A common stock.

     By "Sale  Price"  of the  Class A common  stock on any date we mean (a) the
closing per share sale price on that date as reported in composite  transactions
for the principal United States securities  exchange on which the Class A common
stock is  traded,  (b) if the  Class A common  stock is not  listed  on a United
States  national or regional  securities  exchange,  as reported by the National
Association  of  Securities  Dealers  Automated  Quotation  System  or (c) if no
closing  sale price is  reported,  the  average of the bid and ask prices or, if
more than one in either case, the average of the average bid and the average ask
prices will govern.

     Because the Market Price of the Class A common stock is determined prior to
the  applicable  repurchase  date, you will bear the market risk with respect to
the value of the Class A common stock to be received  from the date we determine
the Market Price to the repurchase date.

     Our right to  repurchase  notes with Class A common stock is subject to our
satisfying various conditions, including:

     o    the  registration of the Class A common stock under the Securities Act
          and the Exchange Act, if required; and

     o    any necessary  qualification  or registration  under  applicable state
          securities  law  or  the   availability  of  an  exemption  from  that
          qualification and registration.

     When we  determine  the actual  number of shares of Class A common stock in
accordance with the foregoing provisions,  we will publish that information in a
daily newspaper of national circulation.

     If the foregoing  conditions  are not satisfied with respect to a holder or
holders prior to the close of business on the  repurchase  date, we will pay you
the repurchase  price of your tendered notes entirely in cash. We may not change
the form of  consideration  to be paid  once we have  given  you the  applicable
notice, except as described in the prior sentence.

     We will comply with the provisions of Rule 13e-4,  Rule 14e-1 and any other
tender offer rules under the Exchange Act that may then be  applicable  and will
file Schedule 13E-4 or any other schedule required thereunder in connection with
any offer by us to purchase notes at your option.

     No notes may be  purchased  for cash at your  option if an event of default
continues  with  respect to the notes  described  under  "Events of Default  and
Remedies"  immediately  below,  other  than  a  default  in the  payment  of the
repurchase price with respect to the notes.

     Payment of the  repurchase  price for a note for which a repurchase  notice
has been delivered and not validly withdrawn is conditioned upon delivery of the
note, together with necessary endorsements to the applicable trustee at any time
after delivery of such repurchase  notice.  Payment of the repurchase  price for
the note will be made promptly following the later of the repurchase date or the
delivery of the note. If the relevant  trustee  holds,  in  accordance  with the
terms of its  indenture,  money or securities  sufficient to pay the  repurchase
price of the note on the business  day  following  the  repurchase  date,  then,
immediately after the repurchase date, the note will cease to be outstanding and
interest and, in the case of 2.25% notes,  original issue discount will cease to
accrue,  whether or not you deliver the note to the trustee.  In that event, all
of your other  rights  shall  terminate,  other  than the right to  receive  the
repurchase price upon delivery of your note.

     Our  ability  to redeem  notes  and to  repurchase  notes  upon a change in
control or at your  option,  as described in the three  preceding  sections,  is
restricted  under  the  terms  of  our  credit  facilities  and  is  effectively
prohibited  during  the  existence  of  a  default  under  them.  See  Notes  to
Consolidated Financial Statements of American Tower in the 1998 Annual Report.




                                      -34-
<PAGE>

Events of Default and Remedies

     An event of  default  is  defined  in each  indenture  as being  any of the
following:

     o    our  default in payment of the  principal  amount at  maturity,  issue
          price  plus  accrued  original  issue  discount  (2.25%  notes  only),
          repurchase price,  optional  redemption price or any change in control
          repurchase price when due, upon maturity, acceleration,  redemption or
          otherwise, on any of the notes,

     o    our default for 30 days in payment of any  installment  of interest on
          the notes,

     o    our default for 60 days after notice in the  observance or performance
          of any other  covenants  in the  applicable  indenture,  and

     o    certain events involving our bankruptcy, insolvency or reorganization.

     Each indenture provides that if any event of default exists, the applicable
trustee or the holders of not less than 25% in principal  amount of the notes of
a relevant series then  outstanding may declare the relevant amount of all notes
of that series to be due and payable  immediately.  The relevant  amount for the
6.25% notes is their principal  amount.  The relevant amount for the 2.25% notes
is the sum of their issue price plus accrued  original issue discount from their
date of issue to the date of  acceleration.  However,  if we cure all  defaults,
except the  nonpayment  of principal  and interest  with respect to any notes of
that series that become due by  acceleration,  and certain other  conditions are
met, the holders of a majority in principal  amount of notes of that series then
outstanding  may rescind that  acceleration.  Holders may  similarly  waive past
defaults.

     The holders of a majority in principal  amount of the notes of the relevant
series then outstanding  have the right to direct the time,  method and place of
conducting any proceedings for any remedy  available to the trustee,  subject to
certain limitations specified in the relevant indenture.

     Each  indenture  provides that the trustee shall give notice to the holders
of notes of any default, except in payment of principal or interest with respect
to the notes, if the trustee, in good faith, considers it in the interest of the
holders of the notes of that series to do so.


Modification of the Indentures

     Each indenture contains provisions  permitting us and the trustee, with the
consent of the  holders of not less than a majority in  principal  amount of the
notes of the relevant  series at the time  outstanding,  to modify the indenture
for that  series  and the  rights of the  holders  of the notes of that  series.
However,  without the consent of the holder of each note so affected,  we cannot
make any modification that will:

     o    extend the final maturity of any notes,

     o    reduce the rate or extend the time for payment of interest,

     o    reduce the principal amount or any premium,

     o    change the accrual rate or time of payment of original  issue discount
          on the 2.25% notes,

     o    change the provisions for redemption at the option of the holders in a
          manner adverse to the holders,

     o    impair or  affect  the  right of a holder  to  institute  suit for the
          payment of principal, interest or any premium,

     o    change the currency in which the notes are payable,



                                      -35-
<PAGE>

     o    impair the right to convert the notes into Class A common stock, or

     o    reduce the  percentage  of notes of that  series,  the  consent of the
          holders of which is required for any modification.


Global Notes, Book-Entry Form

     The notes will be  represented  by global notes,  except as set forth below
under  "--Certificated  Notes." The global notes will be deposited  with,  or on
behalf  of,  DTC and  registered  in the name of Cede & Co.,  as DTC's  nominee.
Beneficial  interests in the global notes will be  exchangeable  for  definitive
certificated notes only in accordance with the terms of the relevant indenture.

     DTC is a limited-purpose trust company organized under the New York Banking
Law, a "banking  organization" within the meaning of the New York Banking Law, a
member of the  Federal  Reserve  System,  a  "clearing  corporation"  within the
meaning  of the New  York  Uniform  Commercial  Code,  and a  "clearing  agency"
registered  pursuant to the  provisions  of Section 17A of the Exchange Act. DTC
holds  securities that its  participants  deposit with DTC. DTC also facilitates
the settlement among participants of securities transactions,  such as transfers
and pledges, in deposited securities through electronic  computerized book-entry
changes in  participants'  accounts,  thereby  eliminating the need for physical
movement of securities  certificates.  Direct  participants  include  securities
brokers and dealers, banks, trust companies, clearing corporations,  and certain
other organizations.  DTC is owned by a number of its direct participants and by
the NYSE, the American Stock Exchange, Inc. and the NASD. Access to DTC's system
is also  available to others such as securities  brokers and dealers,  banks and
trust companies that clear through or maintain a custodial  relationship  with a
direct participant,  either directly or indirectly.  The rules applicable to DTC
and its participants are on file with the SEC.

     Purchases  of  interests in global notes under DTC's system must be made by
or through direct participants,  which will receive a credit for the interest in
the  global  notes on DTC's  records.  The  ownership  interest  of each  actual
purchaser  of each  interest  in the  global  notes (we call it the  "beneficial
owner")  is in turn to be  recorded  on the direct  and  indirect  participants'
records.  Beneficial  owners will not receive written  confirmation  from DTC of
their  purchase,   but  beneficial   owners  are  expected  to  receive  written
confirmations  providing  details  of  the  transaction,  as  well  as  periodic
statements of their holdings,  from the direct or indirect  participant  through
which the beneficial owner entered into the transaction.  Transfers of ownership
interests  in the global  notes are to be  accomplished  by entries  made on the
books of participants  acting on behalf of beneficial owners.  Beneficial owners
will not receive  certificates  representing their ownership interests in global
notes,  except in the event  that use of the  book-entry  system for one or more
global notes is discontinued.

     To  facilitate  subsequent   transfers,   all  global  notes  deposited  by
participants with DTC are registered in the name of DTC's  partnership  nominee,
Cede & Co. The deposit of global  notes with DTC and their  registration  in the
name of  Cede & Co.  effects  no  change  in  beneficial  ownership.  DTC has no
knowledge of the actual  beneficial  owners of the global  notes.  DTC's records
reflect  only the identity of the direct  participants  to whose  accounts  such
global notes are credited,  which may or may not be the beneficial  owners.  The
participants  will remain  responsible  for keeping account of their holdings on
behalf of their customers.

     Conveyance   of  notices  and  other   communications   by  DTC  to  direct
participants,  by direct  participants  to indirect  participants  and by direct
participants and indirect  participants to beneficial owners will be governed by
arrangements among them, subject to any statutory or regulatory  requirements as
may be in effect.

     Redemption  notices  will be sent to  Cede & Co.  If less  than  all of the
global notes are being redeemed,  and unless otherwise  notified by either us or
the relevant  trustee,  DTC's  practice is to determine by lot the amount of the
interest of each direct participant in such issue to be redeemed.



                                      -36-
<PAGE>

     Neither  DTC nor Cede & Co.  will  consent  or vote with  respect to global
notes. Under its usual procedures,  DTC will mail an omnibus proxy to us as soon
as possible  after the record  date.  The  omnibus  proxy  assigns  Cede & Co.'s
consenting or voting rights to those direct  participants  to whose accounts the
global notes are credited on the record date.  This is  identified  in a listing
attached to the omnibus proxy.

     Payment of interest on and the redemption price of the global notes will be
made to DTC.  DTC's practice is to credit direct  participants'  accounts on the
payment date in accordance with their respective holdings shown on DTC's records
unless DTC has reason to believe that it will not receive payment on the payment
date. Payments by participants to beneficial owners will be governed by standing
instructions and customary practices as is the case with securities held for the
accounts of customers in bearer form or  registered in "street name" and will be
the  responsibility  of such  participant  and not of DTC, any agents or us. The
foregoing is subject to any  statutory or regulatory  requirements  as may be in
effect from time to time. Payment of interest on and the redemption price of the
global notes to DTC is our  responsibility.  Disbursement  of payments to direct
participants will be the responsibility of DTC.  Disbursement of payments to the
beneficial   owners  will  be  the   responsibility   of  direct  and   indirect
participants.

     A  beneficial  owner must give notice to elect to have its  interest in the
global  notes  purchased  or tendered,  through its  participant,  to the paying
agent,  and  must  effect  delivery  of this  interest  by  causing  the  direct
participant to transfer the participant's interest in the global notes, on DTC's
records,  to the paying agent.  The requirement for physical  delivery of global
notes in connection  with a demand for purchase of a mandatory  purchase will be
deemed  satisfied when the ownership  rights in the global notes are transferred
by direct participants on DTC's records.

     DTC may  discontinue  providing its services as securities  depositary with
respect to the global notes at any time by giving  reasonable notice to us or to
our  agents.  Under  these  circumstances,  or if DTC is at any time  unable  to
continue as depositary and a successor  depositary is not appointed by us within
90 days, we will cause notes to be issued in definitive form in exchange for the
global notes.

     DTC's management is aware that some computer applications,  systems and the
like for processing  data,  which we refer to collectively as systems,  that are
dependent upon calendar dates may encounter Year 2000 problems. DTC has informed
its  participants  and other  members  of the  financial  community  that it has
developed  and is  implementing  a program so that its systems,  relating to the
timely payment of distributions to  securityholders,  book-entry  deliveries and
settlement  of trades  within  DTC,  continue to  function  appropriately.  This
program includes a technical assessment and a remediation plan, each of which is
complete.  Additionally,  DTC's plan includes a testing phase, which is expected
to be completed within appropriate time frames.

     However,  DTC's ability to perform  properly its services is also dependent
upon other parties,  including  issuers and their agents, as well as third-party
vendors from whom DTC licenses software and hardware, and third-party vendors on
whom DTC relies for  information  or the  provision of services.  This  includes
telecommunication and electrical utility service providers. DTC has informed the
financial  community  that it is in contact  with and will  continue  to contact
third-party vendors from whom DTC acquires services to:

     o    impress  upon them the  importance  of such  services  being Year 2000
          compliant, and

     o    determine the extent of their efforts for Year 2000  remediation  and,
          as appropriate, testing of their services.

In addition,  DTC is in the process of developing  contingency plans as it deems
appropriate.

     According to DTC, the  foregoing  information  with respect to DTC has been
provided to the financial  community for informational  purposes only and is not
intended to serve as a representation,  warranty or contract modification of any
kind. The information in this section concerning DTC and DTC's book-entry system
has been  obtained  from sources that we believe to be reliable,  but we take no
responsibility for the accuracy.



                                      -37-
<PAGE>

     Neither we,  either  trustee,  any paying agent nor the  registrar  for the
notes will have any  responsibility  or liability  for any aspect of the records
relating to or payments  made on account of beneficial  ownership  interest in a
global  security  or for  maintaining,  supervising  or  reviewing  any  records
relating to beneficial ownership interests.


Certificated Notes

     The  notes  represented  by the  global  securities  are  exchangeable  for
certificated notes in definitive form of the same series and of like tenor if:

     o    DTC  notifies  us  that it is  unwilling  or  unable  to  continue  as
          depositary for the global  securities and a successor is not appointed
          within 90 days or if at any time DTC  ceases to be a  clearing  agency
          registered under the Exchange Act,

     o    an event of default has occurred and is continuing, or

     o    we, in our  discretion  and at any time,  determine not to have all of
          the notes represented by the global securities.

     Any notes that are  exchangeable  pursuant to the  preceding  sentence  are
exchangeable for  certificated  notes issuable in authorized  denominations  and
registered in those names as DTC shall  direct.  Subject to the  foregoing,  the
global securities are not exchangeable, except for global securities of the same
aggregate denominations to be registered in the name of DTC or its nominee.


Concerning the Trustee

     The  Bank of New York is a  lender  under  our  credit  facilities  and may
provide other commercial banking services to us in the future.


                                      -38-
<PAGE>

                          DESCRIPTION OF CAPITAL STOCK

     The  description  below  summarizes the more important terms of our capital
stock.  Because this section is a summary,  it does not describe every aspect of
the capital  stock.  This summary is subject to and qualified in its entirety by
reference to the  provisions of our restated  certificate of  incorporation,  as
amended.  We refer to it as the "restated  certificate."  A copy of the restated
certificate has been filed as an exhibit to the registration  statement of which
this prospectus is a part.  Wherever  particular  defined terms or provisions of
the  restated  certificate  are  referred  to,  those terms and  provisions  are
incorporated  by reference as a part of the statements  made, and the statements
are qualified in their entirety by that reference.


General

     Our  authorized  capital stock  consists of 20,000,000  shares of preferred
stock,  $.01 par value per share,  500,000,000  shares of Class A common  stock,
$.01 par value per share,  50,000,000  shares of Class B common stock,  $.01 par
value per share, and 10,000,000  shares of Class C common stock,  $.01 par value
per share.  The number of  outstanding  shares of common  stock as of October 1,
1999 is shown on page 18.


Preferred Stock

     General.   Our  board  of  directors  will   determine  the   designations,
preferences,  limitations and relative  rights of the 20,000,000  authorized and
unissued shares of preferred stock, including:

     o    the  distinctive  designation  of each series and the number of shares
          that will constitute the series,

     o    the voting rights, if any, of shares of the series,

     o    the  dividend  rate on the  shares  of the  series,  any  restriction,
          limitation  or condition  upon the payment of the  dividends,  whether
          dividends  will be  cumulative,  and the dates on which  dividends are
          payable,

     o    the prices at which, and the terms and conditions on which, the shares
          of the series may be redeemed, if the shares are redeemable,

     o    the purchase or sinking fund  provisions,  if any, for the purchase or
          redemption of shares of the series,

     o    any  preferential  amount  payable  upon shares of the series upon our
          liquidation or the distribution of our assets,

     o    the  price  or  rates  of  conversion  at  which,  and the  terms  and
          conditions  on which the shares of the series  may be  converted  into
          other securities, if the shares are convertible, and

     o    whether  the  series  can be  exchanged,  at  our  option,  into  debt
          securities, and the terms and conditions of any permitted exchange.

     The  issuance of  preferred  stock,  or the  issuance of rights to purchase
preferred stock, could discourage an unsolicited acquisition proposal.


                                      -39-
<PAGE>

Common Stock

     Dividends.  Holders of record of shares of common  stock on the record date
fixed by our board of directors are entitled to receive dividends as declared by
our board of  directors  out of funds  legally  available  for the  purpose.  No
dividends  may be declared or paid in cash or property on any share of any class
of common stock, however, unless simultaneously the same dividend is declared or
paid on each share of the other classes of common  stock.  Dividends in the form
of  shares  of  stock  of  any  company,  including  our  company  or any of our
subsidiaries,  are excepted from that requirement.  In that case, the shares may
differ as to voting rights to the extent that voting rights now differ among the
different classes of common stock. In the case of any dividend payable in shares
of common  stock,  holders of each class of common stock are entitled to receive
the same percentage dividend, payable in shares of that class, as the holders of
each other class.  Dividends  and other  distributions  on common stock are also
subject to the rights of holders of any series of  preferred  stock or debt that
may be  outstanding  from time to time.  See  "--Dividend  Restrictions"  on the
following page.

     Voting Rights. Holders of shares of Class A common stock and Class B common
stock have the  exclusive  voting  rights and will vote as a single class on all
matters submitted to a vote of the stockholders. The foregoing is subject to the
requirements of Delaware corporate law, special provisions governing election of
directors and the rights of holders of any series of preferred stock that may be
outstanding from time to time. Each share of Class A common stock is entitled to
one vote and each share of Class B common  stock is entitled  to ten votes.  The
holders of the Class A common stock,  voting as a separate class, have the right
to elect two independent directors. The Class C common stock is nonvoting except
as otherwise required by Delaware corporate law.

     Delaware  corporate law requires the  affirmative  vote of the holders of a
majority  of the  outstanding  shares of any class or series of common  stock to
approve,  among other  things,  a change in the  designations,  preferences  and
limitations  of the shares of that class or series.  The  restated  certificate,
however,  requires the affirmative  vote of the holders of not less than 66 2/3%
of the Class A common stock and Class B common stock,  voting as a single class,
to amend most of the  provisions of the restated  certificate,  including  those
relating  to  the   provisions   of  the  various   classes  of  common   stock,
indemnification of directors,  exoneration of directors for certain acts and the
super-majority provision.

     The restated certificate:

     o    limits  the  aggregate  voting  power  of  Steven  B.  Dodge  and  his
          controlled  entities to 49.99% of the  aggregate  voting  power of all
          shares of capital stock entitled to vote generally for the election of
          directors,  less the voting power represented by the shares of Class B
          common stock acquired by Thomas H. Stoner, a director,  and purchasers
          affiliated with him in the January 1998 private  offering and owned by
          them or any of their  controlled  entities  or family  members  at the
          applicable time,

     o    prohibits  future  issuances  of Class B  common  stock,  except  upon
          exercise of then  outstanding  options and pursuant to stock dividends
          or stock splits,

     o    limits transfers of Class B common stock to permitted transferees,

     o    provides for automatic conversion of the Class B common stock to Class
          A common stock if the aggregate  voting power of Mr. Dodge, Mr. Stoner
          and their respective  controlled entities fall below either (a) 50% of
          Mr. Dodge's initial  aggregate voting power on June 8, 1998; which was
          approximately  42.6%; or (b) 20% of the aggregate  voting power of all
          shares of common stock at the time outstanding, and

     o    requires  the holders of a majority of Class A common stock to approve
          amendments adversely affecting the Class A common stock.

     On October 1, 1999,  our directors and  executive  officers,  together with
their affiliates,  owned  beneficially  approximately 45% of the combined voting
power  of our  common  stock.  On  that  date,  Mr.  Dodge,  together  with  his
affiliates, owned beneficially approximately 29% of the combined voting power.



                                      -40-
<PAGE>

     Conversion  Provisions.  Shares of Class B common  stock and Class C common
stock are convertible,  at any time at the option of the holder,  on a share for
share basis into shares of Class A common  stock.  The present  owner of Class C
common  stock can convert  that stock only upon the  occurrence  of a conversion
event or with the  consent of our board of  directors.  Shares of Class B common
stock  automatically  convert into shares of Class A common stock upon any sale,
transfer,   assignment  or  other   disposition  other  than  (a)  to  permitted
transferees, or (b) pursuant to pledges but not to the pledgee upon foreclosure.
Permitted transferees includes certain family members and other holders of Class
B common stock.

     Liquidation  Rights.  Upon our  liquidation,  dissolution or winding up the
holders  of each  class of common  stock are  entitled  to share  ratably in all
assets available for distribution after payment in full of creditors and payment
in full to holders of preferred stock then outstanding of any amount required to
be paid to them.

     Other  Provisions.  The  holders  of  common  stock  are  not  entitled  to
preemptive  or  subscription  rights.  The  shares  of  common  stock  presently
outstanding are validly issued, fully paid and nonassessable.

     In any merger,  consolidation or business combination,  the holders of each
class of common stock must receive the identical  consideration to that received
by holders of each other class of common stock, except if shares of common stock
or common stock of any other company are  distributed,  the shares may differ as
to voting  rights to the same extent that  voting  rights then differ  among the
different classes of common stock.

     No class of common stock may be subdivided,  consolidated,  reclassified or
otherwise  changed unless,  concurrently,  the other classes of common stock are
subdivided,  consolidated,   reclassified  or  otherwise  changed  in  the  same
proportion and in the same manner.


Dividend Restrictions

     Our borrower  subsidiaries  are prohibited  under the terms of their credit
facilities  from paying cash  dividends  or making  other  distributions  on, or
making  redemptions,  purchases or other acquisitions of, their capital stock or
other equity interests,  including  preferred stock,  except that,  beginning on
April 15,  2002,  if no  default  exists or would be created  thereby  under the
credit  facilities,  our borrower  subsidiaries  may pay cash  dividends or make
other  distributions to the extent that restricted  payments,  as defined in the
credit facilities,  do not exceed (a) 50% of excess cash flow, as defined in the
credit  facilities,  for  the  preceding  calendar  year  or (b)  50% of the net
proceeds of any debt or equity offering after June 16, 1998.


Delaware Business Combination Provisions

     Under Delaware  corporate law, certain "business  combinations,"  including
the  issuance  of equity  securities,  between a  Delaware  corporation  and any
"interested  stockholder" must be approved by the holders of at least 66 2/3% of
the voting stock not owned by the  interested  stockholder  if it occurs  within
three years of the date the person became an interested stockholder.  The voting
requirement  does  not  apply,   however,   if,  before  the  acquisition,   the
corporation's board of directors approved either the business combination or the
transaction  which  resulted in the person  becoming an interested  stockholder.
"Interested stockholder" means any person who owns, directly or indirectly,  15%
or more of the voting power of the  corporation's  shares of capital stock.  The
provision  does not apply to Mr. Dodge  because our board of directors  approved
the transaction pursuant to which he became an interested stockholder.


Listing of Class A Common Stock

     Our Class A common stock is traded on the NYSE under the symbol "AMT."




                                      -41-
<PAGE>

Transfer Agent and Registrar

     The transfer  agent and  registrar for the common stock is Harris Trust and
Savings Bank, 311 West Monroe Street, Chicago,  Illinois 60606 (telephone number
(312) 461-4600).


                             SELLING SECURITYHOLDERS

         The  notes  were  originally  issued  by us and  sold  by  the  initial
purchasers in private transactions exempt from the registration  requirements of
the Securities Act to "qualified  institutional buyers" (as defined in Rule 144A
under the  Securities  Act).  The selling  securityholders,  which term includes
their transferees,  pledgees, donees or their successors,  may from time to time
offer and sell  pursuant to this  prospectus  any or all of the notes and common
stock issuable upon conversion of the notes.

         Prior to any use of this  prospectus in connection with a resale of the
notes and/or the Class A common stock  issuable  upon  conversion  of the notes,
this  prospectus will be supplemented to set forth the name and number of shares
beneficially owned by the selling securityholder  intending to sell notes and/or
Class A common stock and the  principal  amount of notes and/or number of shares
of Class A common  stock to be  offered.  The  prospectus  supplement  will also
disclose  whether  any selling  securityholder  selling in  connection  with the
prospectus  supplement has held any position or office with, been employed by or
otherwise  has had a  material  relationship  with  us or any of our  affiliates
during the three years prior to the date of the prospectus supplement.


                     CERTAIN FEDERAL INCOME TAX CONSEQUENCES

     The following  summary of certain federal income tax  consequences is based
upon the  Internal  Revenue  Code of 1986,  as amended  (the  "Code"),  Treasury
regulations,  and rulings and decisions now in effect,  all of which are subject
to change or  differing  interpretations.  We have not sought a ruling  from the
Internal  Revenue Service with respect to any matter  described in this summary.
We can  provide  no  assurance  that  the IRS or a court  will  agree  with  the
statements  made in this summary.  This summary  applies to you only if you hold
the notes  and  Class A common  stock as a  capital  asset.  A capital  asset is
generally an asset held for  investment  rather than as inventory or as property
used in a trade or business.  The summary  also does not discuss the  particular
tax  consequences  that might be  relevant  to you if you are subject to special
rules under the federal income tax laws.
Special rules apply, for example, if you are:

     o    a bank, life insurance company, regulated investment company, or other
          financial institution,

     o    a broker or dealer in securities or foreign currency,

     o    a person that has a functional currency other than the U.S. dollar,

     o    a person who acquires the notes or Class A common stock in  connection
          with your employment or other performance of services,

     o    a person subject to alternative minimum tax,

     o    a  person  who owns  the  notes  or Class A common  stock as part of a
          straddle, hedging transaction, conversion transaction, or constructive
          sale transaction,

     o    a tax-exempt entity, or

     o    an expatriate.



                                      -42-
<PAGE>

In  addition,   the  following   summary  does  not  address  all  possible  tax
consequences. In particular, it does not discuss any estate, gift, state, local,
or foreign tax consequences.  For all these reasons, we urge you to consult with
your tax advisor about the federal income tax and other tax  consequences of the
acquisition, ownership and disposition of the notes and Class A common stock.

     As explained  below,  the federal  income tax  consequences  of  acquiring,
owning and  disposing of the notes and Class A common stock depend on whether or
not you are a "U.S. holder." For purposes of this summary, you are a U.S. holder
if you are a  beneficial  owner of the  notes or  Class A common  stock  and for
federal income tax purposes are:

     o    a  citizen  or  resident  of the  United  States,  including  an alien
          individual who is a lawful permanent  resident of the United States or
          meets the substantial presence residency test under the federal income
          tax laws,

     o    a corporation, partnership or other entity treated as a corporation or
          partnership  for  federal  income  tax  purposes,  that is  created or
          organized in or under the laws of the United States,  any of the fifty
          states or the  District  of  Columbia,  unless  otherwise  provided by
          Treasury regulations,

     o    an estate the income of which is  subject to federal  income  taxation
          regardless of its source, or

     o    a trust  if a court  within  the  United  States  is able to  exercise
          primary  supervision over the  administration  of the trust and one or
          more  United  States   persons  have  the  authority  to  control  all
          substantial decisions of the trust, or electing trusts in existence on
          August 20, 1996 to the extent provided in Treasury regulations,

and if your status as a U.S. holder is not overridden under the provisions of an
applicable  tax treaty.  Conversely,  you are a  "non-U.S.  holder" if you are a
beneficial owner of the notes or Class A common stock and are not a U.S. holder.


In General

     The notes will be treated as indebtedness  for federal income tax purposes.
This summary discussion assumes that the IRS will respect this classification.

         Payments  you might  receive  on the  notes  that are for  excess  cash
dividends paid on Class A common stock should be treated as potential contingent
interest  payments  and not as  distributions  on stock  potentially  taxable as
ordinary  dividend  income.   Further,  this  summary  discussion  reflects  our
expectation  that only a remote  possibility  exists  that (a) you will  receive
payments  for  excess  cash  dividends  on Class A common  stock or (b) you will
receive additional interest because of a registration default.


Tax Consequences for U.S. Holders


Interest and Excess Cash Dividend Payments on the Notes

     The 6.25%  notes and the 2.25%  notes are  required  to pay  interest  at a
stated fixed rate. You must generally include this stated interest in your gross
income as ordinary interest income:

     o    when you  receive  it, if you use the cash  method of  accounting  for
          federal income tax purposes, or

     o    when it  accrues,  if you use the  accrual  method of  accounting  for
          federal income tax purposes.

Purchase price for a note that is allocable to prior accrued stated interest may
be  treated  as  offsetting  a  portion  of the  interest  income  from the next
scheduled stated interest payment on the note.



                                      -43-
<PAGE>

         If you receive a payment  equivalent to an excess cash dividend paid on
our Class A common stock or a payment of additional  interest for a registration
default, and if the chances of another payment like that occurring in the future
remain remote, then you should report the payment as ordinary interest income in
the  manner  discussed  above,  and the tax  consequences  of the  notes  should
otherwise  remain  unchanged.  In  contrast,  if one or more of  these  types of
payments  cease to remain remote in the future,  then the notes would be treated
as having been retired and reissued with original  issue  discount,  and the tax
consequences  of holding the notes  would then be  governed by special  original
issue  discount rules for contingent  payment debt  instruments.  We urge you to
consult your tax advisor on the  consequences  to you if these events,  which we
believe are remote, should occur.


Original Issue Discount on the 2.25% notes

     In addition to the stated  interest  which you must include in income,  the
2.25% notes will be treated as having  original  issue discount  ("OID"),  which
will  generally  be taxable to you as  interest  income.  The amount of OID on a
2.25% note is the excess of its stated  redemption  price at  maturity  over its
issue price.  A 2.25% note's stated  redemption  price at maturity is the sum of
all payments  expected to be received under the terms of the 2.25% note from the
time  of  issue  until  maturity,  except  for  the  stated  interest  which  is
unconditionally payable semiannually. Its issue price is 70.52% of the principal
amount at maturity.

     You will be  required  under  section  1272 of the Code to include in gross
income, irrespective of your method of accounting, a portion of the OID for each
year  during  which you hold a 2.25%  note,  even  though  the cash to which the
income is  attributable  may not be received until maturity or redemption of the
2.25% note.  The timing of the accrual of OID is based on the 2.25% note's yield
to maturity,  which is its economic, not its stated, interest rate. The economic
interest rate is equal to the present value  discount rate at which all expected
payments on the 2.25% note would have an  aggregate  present  value equal to its
issue price. The yield to maturity of the 2.25% notes is 6.25%,  calculated on a
semi-annual basis from October 4, 1999. The amount of any OID included in income
for a taxable year would be calculated by accruing and  compounding  interest at
the economic interest rate at semiannual intervals corresponding to the payments
of stated  interest on the 2.25%  notes.  This is known as the  "constant  yield
method" of accruing interest.  The excess of the determined  constant yield over
the stated  interest is the amount of OID included in income for that semiannual
period.  The semiannual  amounts of OID are then allocated evenly to each day in
the semiannual  period, and the sum of the OID allocable to the days in your tax
year  constitutes  the OID  includible  in your gross  income for the year.  You
should consult your tax advisor about the possibility of using different accrual
periods and other  assumptions  for purposes of computing OID accruals into your
income.

     The amount of OID you  include  in income  without  actual  receipt of cash
increases  your  basis in your 2.25%  notes for  federal  income  tax  purposes.
Conversely,  your basis is reduced by the  actual  receipt of OID  payments  and
principal  payments.  Similarly,  the issue price of the 2.25% notes is adjusted
upward by OID  accrued  but not  received  and is  decreased  by the  receipt of
payments of OID and principal.  This  "adjusted  issue price" of a 2.25% note is
especially relevant if you purchase a 2.25% note after its original issue.


Acquisition Premium on the 2.25% notes

     If you  purchase  a 2.25%  note at a price in excess  of its then  adjusted
issue price but below its stated  redemption  price at  maturity,  then you will
have paid an  acquisition  premium equal to this excess.  If this happens,  then
each of your subsequent  accruals of OID into gross income is to be reduced by a
percentage  equal to the amount of acquisition  premium divided by the remaining
amount of OID to be accrued at the time you purchased the 2.25% note. If instead
you purchase a 2.25% note at a price in excess of its stated redemption price at
maturity,  then  you need not  include  any OID  accruals  into  income  and the
elective amortization of bond premium described below would apply.


                                      -44-
<PAGE>

Amortizable Bond Premium on the Notes

     If you purchase a 6.25% note for an amount which, when reduced by the value
of the  conversion  feature,  is greater than its  principal  amount,  or if you
purchase  a 2.25%  note for an amount  which,  when  reduced by the value of the
conversion  feature,  is greater than its stated  redemption  price at maturity,
then you will be treated as having purchased that note with "bond premium" equal
to the excess.  You  generally  may elect to amortize this bond premium over the
remaining term of the note on a constant yield method.  The amount  amortized in
any year will be treated as a reduction  of your  interest  income from the note
for that year. If you do not make the election, your bond premium on a note will
decrease  the gain or  increase  the loss that you  otherwise  recognize  on the
note's  disposition.  Any election to amortize bond premium  applies to all debt
obligations,  other than debt  obligations  the interest on which is  excludable
from gross  income,  that you hold at the beginning of the first taxable year to
which the election applies and that you thereafter  acquire.  You may not revoke
an election to amortize bond premium without the consent of the IRS. We urge you
to consult with your tax advisor regarding this election.


Market Discount on the Notes

     If you purchase a 6.25% note for an amount less than its principal  amount,
or if you  purchase a 2.25% note for less than its then  adjusted  issue  price,
then you will be treated as having  purchased  that note at a "market  discount"
equal to the  difference,  unless the amount of the market discount is less than
the de minimis amount specified under the Code. Under the market discount rules,
you will be  required  to  treat  any gain on the  sale,  exchange,  redemption,
retirement,  or other taxable  disposition of a note, or any  appreciation  in a
note in the case of a nontaxable  disposition such as a gift, as ordinary income
to the extent of the market  discount that has not  previously  been included in
your income and that is treated as having  accrued on the note  through the date
of disposition. In addition, you may be required to defer, until the maturity of
the note or earlier  taxable  disposition,  the deduction of all or a portion of
the interest  expense on any  indebtedness  incurred or continued to purchase or
carry the note.

     Any market  discount  will be considered to accrue evenly during the period
from the date of your  acquisition to the maturity date of the note,  unless you
elect to accrue the market  discount on a constant  yield  method.  You may also
elect to include market discount in income currently as it accrues, on either an
even or  constant  yield  method.  If you do so,  your  basis in the  note  will
increase  by the  amounts  you so  include  in your  income.  If you  make  this
election,  the rules described  above regarding  ordinary income on dispositions
and deferral of interest  deductions  will not apply.  This  election to include
market discount in income currently,  once made,  applies to all market discount
obligations  acquired on or after the first  taxable  year to which the election
applies  and may not be revoked  without  the consent of the IRS. We urge you to
consult with your tax advisor regarding these market discount elections.


Redemption or Sale of the Notes

     Generally,  a  redemption  or  sale  of  your  notes  will  result  in your
recognizing  taxable gain or loss equal to the difference  between the amount of
cash or  property  you  receive and your  adjusted  tax basis in the notes.  The
preceding rule does not apply to cash or property  received that is attributable
to accrued interest,  because those amounts would be taxed as interest income in
the manner  described  above.  Your adjusted tax basis in a 6.25% note generally
will be equal to your cost,  increased by any market  discount  included in your
income, and reduced by any bond premium you amortized and principal payments you
received.  Your  adjusted tax basis in a 2.25% note  generally  will be equal to
your cost,  increased by any OID or market discount included in your income, and
reduced by any bond  premium you  amortized  and OID or  principal  payments you
received.  Subject to the market  discount rules described  above,  your gain or
loss will be capital gain or loss and will be long-term  capital gain or loss if
your holding period in the note exceeds one year.




                                      -45-
<PAGE>

Repurchase of the Notes at Your Option

     If you exercise your  repurchase  right,  then your notes will be exchanged
for an amount of cash and Class A common stock.  To the extent the cash or Class
A common stock received  constitutes payment of accrued interest,  those amounts
will be taxed as interest income in the manner  described  above. The balance of
the cash and Class A common  stock will be treated as proceeds  of the  exchange
and taxed in the following  manner. In an exchange of notes solely for cash, the
repurchase  will be treated as a redemption for cash, the  consequences of which
are discussed above. In an exchange of notes involving Class A common stock, the
repurchase should constitute a recapitalization  in which you will not recognize
any taxable gain except to the extent of the cash you receive,  and in which you
will not recognize any loss.  Accordingly,  your tax basis in the Class A common
stock  you  receive  will  equal  your  adjusted  tax  basis  in the  notes  you
surrendered, plus the taxable gain you recognized in the recapitalization, minus
the  amount of cash that you  received  in the  recapitalization.  Your  holding
period in the Class A common stock will include your holding period in the notes
you surrendered in the exchange.


Conversion of the Notes into Class A Common Stock

     You will  generally  not  recognize  any gain or loss on conversion of your
notes  solely into shares of Class A common  stock.  You will have some  taxable
gain if you receive cash in lieu of a fractional  share of Class A common stock.
The cash will be treated as your receipt of a fractional share,  followed by our
redemption  of it for cash.  The  redemption  will be  treated as a sale of your
Class A common  stock which  would  result in your  recognition  of gain or loss
equal to the difference between the cash received and your adjusted tax basis in
the  fractional  share of  Class A  common  stock  redeemed.  Any gain  would be
ordinary  income to the extent of any accrued market discount on your notes that
you have not previously  included in your income, and otherwise would be capital
gain.  Your holding period in the Class A common stock will include your holding
period in the notes you surrendered in the conversion.

     Your income tax basis for the shares of Class A common stock  received upon
conversion  will be equal to the adjusted  tax basis of the notes you  exchange,
except for any adjustment necessary because of your receipt of cash in lieu of a
fractional  share of Class A common  stock.  Any  accrued  market  discount  not
previously included in income as of the date of the conversion of the notes will
carry over to the Class A common stock received on conversion and will give rise
to ordinary income upon the subsequent disposition of that stock.

     Distributions  on Class A  common  stock  are  treated  first  as  ordinary
dividend  income to the extent paid out of our current or  accumulated  earnings
and profits,  next as a nontaxable  return of capital that reduces your basis in
the  stock  dollar-for-dollar  until the basis  has been  reduced  to zero,  and
finally as gain from the sale or exchange  of the stock.  We do not at this time
anticipate  making  distributions  on the Class A common  stock.  Subject to the
market discount rules discussed above, your sale or other taxable disposition of
Class A common stock will generally  result in capital gain or loss equal to the
difference  between the amount of cash or property you receive and your adjusted
tax basis in the stock.


Potential Distributions Resulting from Adjustment of Conversion Price

     Your rights to convert  your notes into Class A common  stock allow for the
conversion  price to be adjusted under a number of  circumstances,  generally to
ensure  that you  receive an  economically  equivalent  number of shares  from a
conversion  following  stock  splits and stock  dividends  of our Class A common
stock.  Section  305  of the  Code  may  treat  some  of  these  adjustments  as
constructive  taxable  distributions of stock. This would generally occur if the
conversion price is adjusted for a taxable  distribution to the holders of Class
A common stock. Constructive  distributions so treated would be taxable first as
dividends  to the extent paid out of our  current or  accumulated  earnings  and
profits,  next as a nontaxable  return of capital to the extent of your basis in
the notes,  and  finally as gain from the sale or  exchange  of the notes.  Your
adjusted tax basis in the notes would be increased by constructive distributions
to you taxable as dividends or gain,  and would be  unaffected  by  constructive
distributions that were nontaxable returns of capital.  Conversely, a failure to
appropriately  adjust  the  conversion  price of the  notes  could


                                      -46-
<PAGE>

result in a  constructive  distribution  to holders of Class A common stock that
would be taxable to them in a similar manner.


Special Tax Consequences for Non-U.S. Holders

     The federal income tax attributes of the notes and Class A common stock for
non-U.S.  holders are  generally  comparable to those  described  above for U.S.
holders.  However, special federal income tax rules apply to non-U.S. holders as
described below.


In General

     If you are a non-U.S.  holder, you will generally not be subject to federal
income taxes on payments of principal,  premium, if any, or interest or OID on a
note or upon the sale, exchange, redemption,  retirement or other disposition of
a note or Class A common stock, if:

     o    you do not own directly or indirectly  10% or more of the total voting
          power of all classes of our voting stock,

     o    your income and gain in respect of the note or Class A common stock is
          not effectively connected with the conduct of a United States trade or
          business,

     o    you are not a  controlled  foreign  corporation  that is related to or
          under common control with us,

     o    we or the  applicable  withholding  agent  have  received  from  you a
          properly  executed,  applicable IRS Form W-8 or substantially  similar
          form in the year in which a payment of interest,  OID,  principal,  or
          premium  on a note  occurs,  or in a  preceding  calendar  year to the
          extent  provided for in the  instructions  to the  applicable IRS Form
          W-8,

     o    in the case of gain upon the sale, exchange, redemption, retirement or
          other  disposition of a note or Class A common stock  recognized by an
          individual non-U.S.  holder, you were present in the United States for
          less  than 183 days  during  the  taxable  year in which  the gain was
          recognized, and

     o    section 897 of the Code, discussed below, does not apply to you.

     The IRS Form W-8 or substantially  similar form must be signed by you under
penalties of perjury  certifying  that you are a non-U.S.  holder and  providing
your name and address.  You must inform the  withholding  agent of any change in
the  information  on the statement  within 30 days of the change.  If you hold a
note or Class A common stock through a securities clearing organization or other
qualified financial  institution,  the organization or institution may provide a
signed  statement to the withholding  agent.  However,  in that case, the signed
statement  must  generally be accompanied by a copy of the executed IRS Form W-8
or  substantially  similar  form  that  you  provided  to  the  organization  or
institution.

     Except in the case of income or gain that is effectively connected with the
conduct of a United States trade or business,  discussed below,  interest,  OID,
dividends or gain  recognized by you which does not qualify for  exemption  from
taxation will be subject to federal income tax and  withholding at a rate of 30%
unless reduced or eliminated by an applicable tax treaty.  For example,  neither
constructive  distributions  on notes  taxable as  dividends,  nor  excess  cash
dividend  payments on notes, nor dividends on Class A common stock would qualify
for exemption  from  taxation,  although an applicable tax treaty may reduce the
tax rate on these  items to below 30%.  You may  generally  use IRS Form 1001 to
claim tax  treaty  benefits  for  calendar  years  1999 and 2000,  and under new
Treasury regulations discussed below an applicable IRS Form W-8 or substantially
similar form for subsequent calendar years.


                                      -47-
<PAGE>

Effectively Connected Income and Gain

     If you are a non-U.S.  holder whose income and gain in respect of a note or
Class A common  stock is  effectively  connected  with the  conduct  of a United
States trade or business,  you will be subject to regular  federal income tax on
this income and gain in generally the same manner as U.S.  holders,  and general
federal income tax return filing  requirements  will apply. In addition,  if you
are a  corporation,  you may be subject to a branch  profits tax equal to 30% of
your effectively  connected  adjusted earnings and profits for the taxable year,
unless you qualify for a lower rate under an applicable tax treaty. To obtain an
exemption from  withholding on interest,  dividends,  and OID, you may generally
supply to the  withholding  agent an IRS Form 4224 for  calendar  years 1999 and
2000, and under new Treasury regulations  discussed below an applicable IRS Form
W-8 or substantially similar form for subsequent calendar years.

     We believe  that we are  currently a United  States real  property  holding
corporation,  and that we are likely to remain one. Because of this, section 897
of the Code and the applicable Treasury  regulations  potentially cause any gain
or loss you realize upon a disposition  of your notes or Class A common stock to
be treated as  effectively  connected with the conduct of a trade or business in
the United States, and thus taxable as effectively  connected gain in the manner
described above.  Section 897 can also cause realized gains that would otherwise
remain  unrecognized,  for example  gains in a  recapitalization  where you have
required us to repurchase  your note in exchange for Class A common stock, to be
recognized in full absent compliance with procedural  requirements under section
897.  We  believe  that,  provided  our  Class A common  stock  continues  to be
regularly traded on the New York Stock Exchange,  you will not recognize taxable
gain  under  section  897 on a  disposition  of a 6.25% or 2.25% note or Class A
common stock, so long as you meet the following three standards:

     o    you have not  directly  or  indirectly  owned,  at any time during the
          five-year period preceding the disposition,  more than 5% of the total
          outstanding 6.25% notes or more than 5% of the total outstanding 2.25%
          notes;

     o    you have not  directly or  indirectly  owned more than 5% of the total
          outstanding  Class A common  stock at any time  during  the  five-year
          period preceding the disposition; and

     o    upon the date of your  acquisition  of any of the  notes or any  other
          interests  in our  company  not  regularly  traded  on an  established
          securities  market,  the aggregate  fair market value of your directly
          and  indirectly  owned  notes,  plus  any of your  other  directly  or
          indirectly  owned interests in our company not regularly  traded on an
          established  securities  market,  does not exceed 5% of the  aggregate
          value of our outstanding Class A common stock.

We urge you to consult with your tax advisor to determine whether you meet these
three standards, or whether you otherwise qualify for exemption from section 897
of the Code.


Our Deductions for Interest and OID on the Notes

     Under  section  279  of  the  Code,  deductions  otherwise  allowable  to a
corporation  for  interest and OID expense may be reduced or  eliminated  in the
case of  "corporate  acquisition  indebtedness."  This is defined  generally  to
include  subordinated  convertible debt issued to provide  consideration for the
acquisition  of  stock  or a  substantial  portion  of  the  assets  of  another
corporation, where the acquiring corporation does not meet statutorily specified
debt/equity  ratio and earnings  coverage tests. Our deductions for interest and
OID expense on any notes could be reduced or  eliminated  if the notes so issued
meet  the  definition  of  corporate  acquisition  indebtedness  in the  year of
issuance.  Also, the notes could become corporate acquisition  indebtedness in a
subsequent year if we initially meet the debt/equity ratio and earnings coverage
tests,  but  later  fail  them  in a  year  during  which  we  issue  additional
indebtedness  for  corporate  acquisitions.  Because the notes are not expressly
subordinated  to any of our unsecured  debt, and because the notes have the same
creditor  priority as more than an  insubstantial  amount of our trade debt,  we
believe the notes are not subordinated  within the meaning of section 279 of the
Code and therefore do not constitute corporate acquisition indebtedness.



                                      -48-
<PAGE>

     Under  section  163(l) of the Code,  our  deduction  for  interest  and OID
expense on the notes would be disallowed  if they are found to be  "disqualified
debt instruments." Disqualified debt instruments are debt instruments:

     o    where a substantial amount of the principal or interest is required to
          be paid or  converted,  or at the  option  of the  issuer or a related
          party is payable in or convertible into, issuer equity, or

     o    which are part of an arrangement that is reasonably expected to result
          in a transaction described in the preceding clause.

For these  purposes,  principal or interest on a debt  instrument  is treated as
required  to be paid in or  converted  into  issuer  equity  if the  payment  or
conversion  may be  required  at the  option of the  holder  and that  option is
substantially  certain to be  exercised.  We do not believe  that  principal  or
interest  on the notes is required  to be paid in or  converted  into our equity
under  section  163(l),  because  principal or interest on our notes may only be
exchanged  for  equity in our  company  at the  holder's  option,  and we do not
believe that this option is substantially certain to be exercised.  Furthermore,
the  legislative  history of section 163(l)  indicates that the provision is not
intended  to apply to debt  instruments  with a  conversion  feature  where  the
conversion price is  significantly  higher than the market price of the stock on
the issue date of the debt.  We believe that the  conversion  price of the notes
was  significantly  higher than the market  price of our Class A common stock on
the date the notes were issued.  Accordingly,  we believe that the notes are not
disqualified  debt instruments  under section 163(l) of the Code.  However,  our
conclusions  in this regard are factual  judgments as to which no legal  opinion
can be given.  In any event,  we cannot assure you that the IRS or a court would
agree with our conclusions.


Information Reporting, Income Tax Withholding and Backup Withholding

     Information reporting,  income tax withholding,  and backup withholding may
apply  to  interest,   OID,  dividend  and  other  payments  to  you  under  the
circumstances  discussed below. Amounts withheld are generally not an additional
tax and may be refunded or credited  against your federal  income tax liability,
provided you furnish the required information to the IRS.

     If You are a U.S. Holder. You may be subject to backup withholding at a 31%
rate when you receive interest,  OID, and dividends with respect to the notes or
Class A common  stock,  or when you receive  proceeds  upon the sale,  exchange,
redemption,  retirement  or  other  disposition  of the  notes or Class A common
stock. In general,  you can avoid this backup  withholding by properly executing
under  penalties of perjury an IRS Form W-9 or  substantially  similar form that
provides:


     o    your correct taxpayer identification number, and

     o    a  certification  that  (a) you are  exempt  from  backup  withholding
          because you are a corporation or come within another enumerated exempt
          category,  (b) you  have  not  been  notified  by the IRS that you are
          subject to backup  withholding,  or (c) you have been  notified by the
          IRS that you are no longer subject to backup withholding.

If you do not provide your  correct  taxpayer  identification  number on the IRS
Form W-9 or substantially  similar form, you may be subject to penalties imposed
by the IRS.

     Unless  you  have  established  on a  properly  executed  IRS  Form  W-9 or
substantially  similar form that you are a  corporation  or come within  another
enumerated  exempt category,  interest,  OID, dividend and other payments on the
notes or Class A common  stock  paid to you during the  calendar  year,  and the
amount of tax withheld, if any, will be reported to you and to the IRS.



                                      -49-
<PAGE>

     Special Rule for U.S. Holders  Beneficially Owned by Non-U.S.  Holders.  As
stated  above,  we believe that we are  currently a United  States real property
holding  corporation  under  section 897 of the Code,  and that we are likely to
remain one.  Section 1445 of the Code governs income tax  withholding  for gains
taxable  to  non-U.S.  holders  under  section  897.  It  provides  that  upon a
disposition of the notes or Class A common stock,  income tax withholding may be
required of disposing U.S. holders that are partnerships,  trusts,  estates, and
other entities because of their  beneficial  ownership by non-U.S.  holders.  We
believe that, provided our Class A common stock continues to be regularly traded
on the New York Stock Exchange, you will not have to withhold upon a disposition
of the notes or Class A common stock under  section 1445 of the Code if you meet
the 5% thresholds discussed above that are applicable to non-U.S. holders on the
disposition  of the notes and Class A common stock.  We urge you to consult with
your tax advisor to determine  whether you meet these standards,  or whether you
otherwise qualify for exemption from sections 897 and 1445 of the Code.

     Special Rule for Substantial Acquisitions from Non-U.S.  Holders. As stated
above,  we  believe we are  currently  a United  States  real  property  holding
corporation  under  section  897 of the Code,  and we are likely to remain  one.
Because of this,  section 1445 of the Code may require a person  acquiring notes
from a non-U.S. holder to withhold 10% of the purchase price. However,  provided
our Class A common stock continues to be regularly  traded on the New York Stock
Exchange,  this 10%  withholding is generally not required for an acquisition of
notes where the  purchase  price  constitutes  5% or less of the then  aggregate
value of the outstanding  Class A common stock. We urge you to consult with your
tax  advisor  to  determine  whether  you meet this  standard,  or  whether  you
otherwise qualify for exemption from section 1445 of the Code.

     If You are a Non-U.S.  Holder.  The amount of interest,  OID, and dividends
paid to you on a note or Class A common stock during each calendar year, and the
amount of tax  withheld,  if any,  will  generally be reported to you and to the
IRS. This information  reporting  requirement  applies regardless of whether you
were subject to withholding or whether  withholding was reduced or eliminated by
an applicable tax treaty. Also, interest,  OID, and dividends paid to you may be
subject to backup  withholding at a 31% rate,  unless you properly  certify your
non-U.S.  holder  status  on an IRS  Form  W-8 or  substantially  similar  form.
Similarly,  information  reporting and 31% backup  withholding will not apply to
proceeds you receive upon the sale,  exchange,  redemption,  retirement or other
disposition of the notes or Class A common stock,  if you properly  certify that
you are a non-U.S. holder on an IRS Form W-8 or substantially similar form. Even
without having executed an IRS Form W-8 or substantially  similar form, however,
in some cases information reporting and 31% backup withholding will not apply to
proceeds you receive upon the sale,  exchange,  redemption,  retirement or other
disposition  of the notes or Class A common stock if you receive those  proceeds
through a broker's foreign office.

     If you are a non-U.S.  holder whose income and gain on the notes or Class A
common stock are effectively connected with the conduct of a United States trade
or business,  a slightly  different  rule may apply to proceeds you receive upon
the  sale,  exchange,  redemption,  retirement  or  other  disposition  of those
securities.  Until you comply with the new Treasury regulations discussed below,
information  reporting and 31% backup  withholding  may apply to you in the same
manner as to a U.S. holder,  and thus you may have to execute an IRS Form W-9 or
substantially similar form to prevent the backup withholding.

     New Treasury  Regulations.  New Treasury  regulations alter the withholding
rules on interest,  OID,  dividends,  and sale or exchange proceeds paid to you,
effective  generally for payments after December 31, 2000 and subject to complex
transition rules. For example,  documentation and procedures  satisfying the new
Treasury  regulations  are  deemed in some  instances  to  satisfy  current  law
requirements.  In  these  instances  you or the  withholding  agent  may wish to
satisfy  the  requirements  of the new  Treasury  regulations  rather  than  the
requirements  of the  Treasury  regulations  soon to  expire.  The new  Treasury
regulations  are  complex,  and we urge you to consult  with your tax advisor to
determine how the new Treasury regulations affect your particular circumstances.

     The new Treasury  regulations replace old IRS Forms W-8, 1001 and 4224 with
a new series of IRS Forms W-8, which you will generally have to properly execute
earlier  than  you  would  have  otherwise  had to  for  purposes  of  providing
replacements for the old IRS forms.  For example,  you must properly execute the
appropriate new version of IRS Form W-8, or substantially similar form, no later
than  December 31, 2000 if you remain a non-U.S.  holder of the notes or Class A
common stock on that date.  Under the new Treasury  regulations,  it may also be
possible  for


                                      -50-
<PAGE>

you to receive  payments on those  securities  through a qualified  intermediary
that complies with requisite procedures and provides applicable certification of
your non-U.S.  holder status on your behalf.  The new Treasury  regulations also
clarify  withholding  agents' standards of reliance on executed IRS Forms W-8 or
substantially similar forms.

     If you are a non-U.S.  holder claiming benefits under an income tax treaty,
you should be aware that you may be required to obtain a taxpayer identification
number and to certify your eligibility under the applicable treaty's limitations
on  benefits  article  in order to  comply  with the new  Treasury  regulations'
certification  requirements.  The new Treasury  regulations also provide special
rules to determine  whether,  for purposes of determining the applicability of a
tax  treaty,  amounts  paid to a  non-U.S.  holder  that is an entity  should be
treated as paid to the entity or to those  holding the  ownership  interests  in
that entity, and whether the entity or the holders in the entity are entitled to
benefits under the tax treaty.



                          REGISTRATION RIGHTS AGREEMENT

     On October 4, 1999, we entered into a  registration  rights  agreement with
the  initial  purchasers  for the  benefit of the  holders  of the  notes.  That
agreement obligates us, at our sole expense, as follows:

     o    use our reasonable best efforts to file a shelf registration statement
          as soon as  practicable,  but in no event  more than 90 days after the
          issue of the  notes,  covering  resales  of the  notes and the Class A
          common  stock  issuable  upon  their  conversion.  We  refer  to those
          securities collectively as the "registrable securities;"

     o    to use our  reasonable  best  efforts to cause the shelf  registration
          statement to be declared effective under the Securities Act within 150
          days after the issue of the notes; and

     o    to use our  reasonable  best  efforts  to keep the shelf  registration
          statement  effective  and usable  for two years or such other  shorter
          period as shall be required under Rule 144(k) of the  Securities  Act.
          We  are  permitted,   however,   to  suspend  the  use  of  the  shelf
          registration   statement  during  certain   black-out  periods  if  we
          determine  in good  faith  that it is in our best  interest  and if we
          provide the registered  holders with written notice of the suspension.
          The period may not  exceed 30 days in any  three-month  period and may
          not exceed 90 days in the  aggregate  in any 12-month  period.  We are
          also not  required to maintain  the shelf  registration  statement  if
          prior to the end of that two-year  period or other shorter Rule 144(k)
          period all the  registrable  securities have been sold under the shelf
          registration   statement,   transferred   under  Rule  144  under  the
          Securities Act or otherwise transferred in a way that eliminates their
          Securities   Act   transfer   restrictions   for  future   resales  by
          non-affiliates.

     The registration statement of which this prospectus is a part satisfies the
first two of the foregoing requirements.

     We are obligated to:

     o    provide  each  holder of  registrable  securities  with copies of this
          prospectus;

     o    notify  each such holder when the  registration  statement  has become
          effective, and

     o    take  certain  other  actions as are  required to permit  unrestricted
          resales of the registrable securities.

     If you sell registrable securities pursuant to the registration  statement,
you (a) will usually be required to be named as a selling securityholder in this
prospectus and to deliver this prospectus to purchasers,  (b) will be subject to
certain of the civil liability provisions under the Securities Act in connection
with  your  sales,  and (c) will be bound by the  applicable  provisions  of the
registration  rights  agreement,  including certain  indemnification  rights and
obligations.



                                      -51-
<PAGE>

     If a registration default occurs, the interest rate will be increased 0.50%
per annum,  subject to certain exceptions.  Following the cure of a registration
default,  the interest rate will become the rate in effect  immediately prior to
the registration default. We use the term "registration default" to mean if:

     o    we fail to timely file the shelf  registration  statement with the SEC
          within 90 days of closing,

     o    the SEC has not declared the shelf  registration  statement  effective
          within 150 days of closing, or

     o    we fail  to keep  the  shelf  registration  statement  that  has  been
          declared  effective  continuously  effective  and  usable,  subject to
          certain exceptions, for the period required.

     Each registrable  security  contains a legend to the effect that the holder
is  deemed  to have  agreed to be bound by the  provisions  of the  registration
rights agreement.

     The summary of certain provisions of the registration rights agreement does
not purport to be complete  and is subject to, and is  qualified in its entirety
by reference to, all the provisions of the registration rights agreement, a copy
of which has been  filed as an exhibit to the  registration  statement  of which
this prospectus is a part.


                              PLAN OF DISTRIBUTION

     The  notes  and  Class A  common  stock  may be sold  from  time to time to
purchasers directly by the selling securityholders.  Alternatively,  the selling
securityholders   may  from  time  to  time  offer  the  notes  with  discounts,
concessions  or  commissions  from  the  selling   securityholders   and/or  the
purchasers of the notes and Class A common stock for whom they may act as agent.
The  selling  securityholders  and any  such  brokers,  dealers  or  agents  who
participate  in the  distribution  of the notes and Class A common  stock may be
deemed to be "underwriters,"  and any profits on the sale of the notes and Class
A common stock by them and any discounts, commissions or concessions received by
any such brokers, dealers or agents might be deemed to be underwriting discounts
and   commissions   under  the  Securities   Act.  To  the  extent  the  selling
securityholders  may be deemed to be underwriters,  the selling  securityholders
may be subject to certain statutory liabilities,  including, but not limited to,
Sections 11, 12 and 17 of the  Securities  Act and Rule 10b-5 under the Exchange
Act.

     The notes and  underlying  Class A common  may be sold from time to time in
one or more  transactions  at fixed prices,  at prevailing  market prices at the
time of sale, at varying prices  determined at the time of sale or at negotiated
prices.  The notes  and  Class A common  stock may be sold by one or more of the
following methods:

     o    a block trade in which the broker or dealer so engaged will attempt to
          sell the notes  and  Class A common  stock  issuable  upon  conversion
          thereof as agent but may position and resell a portion of the block as
          principal to facilitate the transaction;

     o    purchases by a broker or dealer as principal and resale by such broker
          or dealer for its account pursuant to this prospectus;

     o    ordinary  brokerage  transactions and transactions in which the broker
          solicits purchasers;

     o    an  exchange  distribution  in  accordance  with  the  rules  of  such
          exchange;

     o    face-to-face  transactions  between  sellers and purchasers  without a
          broker-dealer;

     o    through the writing of options; and

     o    other transactions.



                                      -52-
<PAGE>

     At any time a  particular  offer of the notes  and Class A common  stock is
made, a revised  prospectus  or  prospectus  supplement,  if  required,  will be
distributed  which will set forth the  aggregate  amount and type of  securities
being offered and the terms of the offering,  including the name or names of any
underwriters,  dealers or agents,  any discounts,  commissions,  concessions and
other items constituting  compensation from the selling  securityholders and any
discounts,  commissions or concessions  allowed or reallowed or paid to dealers.
The prospectus supplement and, if necessary,  a post-effective  amendment to the
registration  statement of which this  prospectus is a part,  will be filed with
the SEC to reflect the disclosure of additional  information with respect to the
distribution of the notes and Class A common stock.  In addition,  the notes and
Class A  common  stock  covered  by  this  prospectus  may be  sold  in  private
transactions or under Rule 144 rather than pursuant to this prospectus.

     We have agreed in the registration rights agreement to keep this prospectus
useable until October 4, 2001 as described under "Registration Rights Agreement"
on page 51. To our knowledge currently no plans,  arrangements or understandings
exist  between any selling  securityholders  and any  broker,  dealer,  agent or
underwriter regarding the sale of the securities by the selling securityholders.
We cannot assure you that any selling securityholder will sell any or all of the
securities   offered  by  it  under  this   prospectus   or  that  any   selling
securityholder will not transfer,  devise or gift such securities by other means
not described in this prospectus.

     The selling  securityholders  and any other  person  participating  in such
distribution  will be subject to  applicable  provisions of the Exchange Act and
the rules and regulations thereunder,  including, without limitation, Regulation
M. That  regulation  may limit the timing of  purchases  and sales of any of the
notes  and Class A common  stock by the  selling  securityholders  and any other
participating person. Furthermore, Regulation M of the Exchange Act may restrict
the ability of any person engaged in the  distribution  of the notes and Class A
common  stock  to  engage  in  market-making  activities  with  respect  to  the
particular  notes and Class A common stock being  distributed for a period of up
to five business days prior to the commencement of the distribution.  All of the
foregoing may affect the marketability of the notes and Class A common stock and
the ability of any person or entity to engage in  market-making  activities with
respect to the notes and Class A common stock.

     Pursuant to the registration  rights  agreement  entered into in connection
with our initial private placement,  we and each of the selling  securityholders
will be indemnified by the other against certain liabilities,  including certain
liabilities  under the Securities  Act, or will be entitled to  contribution  in
connection with these matters.

     We have agreed to pay substantially  all of the expenses  incidental to the
registration, offering and resale by the selling securityholders of the notes to
the public other than commissions, fees and discounts of underwriters,  brokers,
dealers and agents.

     We will  not  receive  any of the  proceeds  of the sale of the  notes  and
underlying Class A common stock covered by this prospectus.

                                      -53-
<PAGE>




                                  LEGAL MATTERS

     The  validity  of the  notes  and any Class A common  stock  issuable  upon
conversion  of such notes have been  passed  upon for us by Sullivan & Worcester
LLP, Boston,  Massachusetts.  Sullivan & Worcester LLP,  Boston,  Massachusetts,
also passed upon certain  matters  relating to United States  federal income tax
considerations  for us, as our special tax counsel.  Norman A. Bikales, a member
of the firm of Sullivan & Worcester  LLP, is the owner of 11,000 shares of Class
A common  stock and 41,490  shares of Class B common  stock and has an option to
purchase 20,000 shares of Class A common stock at $10.00 per share. An associate
of Sullivan & Worcester  LLP has an option to purchase  8,000  shares of Class A
common stock at $18.75 per share.  Mr.  Bikales  and/or  associates of that firm
serve as our secretary or assistant secretaries and certain of our subsidiaries.


                                     EXPERTS

     The consolidated  financial  statements of American Tower Corporation as of
December  31,  1998 and 1997 and for each of the years in the three year  period
ended December 31, 1998  incorporated  by reference in this  prospectus from the
Company's  Annual  Report on Form 10-K,  have been  audited by Deloitte & Touche
LLP,  independent  auditors,  as stated in their report,  which is  incorporated
herein by reference, and has been so incorporated in reliance upon the report of
such firm given upon their authority as experts in accounting and auditing.

     The following  financial  statements are  incorporated by reference in this
prospectus from the Form 8-K dated September 17, 1999:

     o    The consolidated  financial  statements of American Tower  Corporation
          and subsidiaries as of December 31, 1997 and 1996, and for each of the
          years in the three  year  period  ended  December  31,  1997 have been
          incorporated  by reference  in this  prospectus  in reliance  upon the
          report of KPMG LLP, independent auditors, incorporated by reference in
          this  prospectus,  and upon the  authority  of said firm as experts in
          accounting and auditing.

     o    The  consolidated  financial  statements  of  OmniAmerica,   Inc.  and
          Subsidiaries  (formerly Specialty  Teleconstructors,  Inc.) at and for
          the year  ended  June 30,  1998,  incorporated  by  reference  in this
          prospectus  have  been  audited  by  Ernst  & Young  LLP,  independent
          auditors,  as stated in their report incorporated by reference herein,
          and are  incorporated by reference herein in reliance upon such report
          given on the  authority  of such firm as  experts  in  accounting  and
          auditing.

     o    The consolidated  financial statements of OmniAmerica,  Inc. (formerly
          Specialty  Teleconstructors,  Inc.) as of and for the year  ended June
          30, 1997 have been  incorporated  by reference in this  prospectus  in
          reliance   upon  the  report  of  KPMG  LLP,   independent   auditors,
          incorporated by reference in this  prospectus,  and upon the authority
          of said firm as experts in accounting and auditing.

     o    The financial statements of TeleCom Towers,  L.L.C. as of December 31,
          1998 and 1997 and for the year ended  December  31, 1998 and the three
          month period from  September  30, 1997 (date of inception) to December
          31, 1997 and the financial  statements of Telecom Southwest Towers LP,
          Telecom Towers  Mid-Atlantic LP, and Telecom Towers of the West, L.P.,
          as of July 31,  1998 and  December  31,  1997 and for the seven  month
          period  ended July 31,  1998 and the year  ended  December  31,  1997,
          incorporated  by  reference  in this  prospectus  have been audited by
          Ernst & Young LLP,  independent  auditors,  as stated in their reports
          appearing  therein,  and as to the seven month  period  ended July 31,
          1998 and the year ended December 31, 1997 as related to Telecom Towers
          Mid-Atlantic, LP and as to the year ended December 31, 1998 as related
          to  Telecom  Towers,  LLC is based in part on the  report of KPMG LLP,
          independent  auditors,  as set forth in their report on the  financial
          statements of RCC Consultants,  Inc. (not separately  presented in the
          Form 8-K)  appearing  therein.  The financial  statements  referred to
          above are  included  in  reliance  upon such  reports  given  upon the
          authority of such firms as experts in accounting and auditing.



                                      -54-
<PAGE>

     o    The financial statements of Wauka  Communications,  Inc. as of October
          26,  1998 and  December  31, 1997 and for the ten month  period  ended
          October 26, 1998 and year ended  December  31,  1997  incorporated  by
          reference in this prospectus have been audited by Arthur Andersen LLP,
          independent auditors, as stated in their report appearing therein.

     o    The   consolidated   financial   statements   of  UNIsite,   Inc.  and
          subsidiaries  as of  December  31,  1998  and 1997 and for each of the
          years in the three  year  period  ended  December  31,  1998 have been
          incorporated  by reference  in this  prospectus  in reliance  upon the
          report of KPMG LLP, independent auditors, incorporated by reference in
          this  prospectus,  and upon the  authority  of said firm as experts in
          accounting and auditing.


                       WHERE YOU CAN FIND MORE INFORMATION

         We file annual,  quarterly and current  reports,  proxy  statements and
other information with the SEC. You may read and copy any reports, statements or
other  information  on file at the  SEC's  public  reference  room at 450  Fifth
Street, N.W., Washington,  D.C. 20549. You can request copies of those documents
upon payment of a duplicating  fee to the SEC. You may also review a copy of the
registration  statement at the SEC's regional  offices in Chicago,  Illinois and
New  York,  New  York.  Please  call  the  SEC  at  1-800-SEC-0330  for  further
information on the operation of the public  reference  rooms. You can review our
SEC filings and the registration  statement by accessing the SEC's Internet site
at http://www.sec.gov.

         The SEC allows us to "incorporate by reference" the information we file
with them.  This  means that we can  disclose  important  information  to you by
referring you to those documents.  The information  incorporated by reference is
considered  to be  part  of  this  prospectus.  Statements  in  this  prospectus
regarding  the contents of any  contract or other  document may not be complete.
You  should  refer to the copy of the  contract  or other  document  filed as an
exhibit to the registration statement. Later information filed with the SEC will
update and supersede  information we have included or  incorporated by reference
in this prospectus.

         We incorporate by reference the documents  listed below and any filings
made after the date of the  original  filing of the  registration  statement  of
which this prospectus is a part made with the SEC under Section 13(a), 13(c), 14
or 15(d) of the Securities Exchange Act of 1934 until this offering is completed
or terminated:

     o    our Annual Report on Form 10-K for the fiscal year ended  December 31,
          1998 (the "1998 Annual Report"),

     o    our proxy statement for our 1999 annual meeting of stockholders,

     o    our Quarterly Reports on Form 10-Q for the quarters ended March 31 and
          June 30, 1999 (the "March  1999  Quarterly  Report" and the "June 1999
          Quarterly Report"), and

     o    (a) our Current Reports on Form 8-K dated January 8, 1999, January 21,
          1999,  February 12, 1999,  February 24, 1999,  March 5, 1999, July 16,
          1999,  September 17, 1999 and September 21, 1999;  and (b) our Current
          Reports on Form 8-K/A dated January 27, 1999 and March 18, 1999.

     We will  provide  a copy of the  documents  we  incorporate  by  reference,
excluding  exhibits  other than those to which we  specifically  refer.  You may
obtain  this  information  at no cost  by  writing  or  telephoning  us at:  116
Huntington  Avenue,  Boston,  Massachusetts  02116,  (617) 375-7500,  Attention:
Director of Investor Relations.

                                      -55-

<PAGE>









                                      LOGO




<PAGE>

                           AMERICAN TOWER CORPORATION
                       REGISTRATION STATEMENT ON FORM S-3


                                     PART II

                   INFORMATION NOT REQUIRED IN THE PROSPECTUS

        Item 14. Other Expenses of Issuance and Distribution.

              The following  expenses are the estimated expenses of the issuance
        and distribution of the securities  (other than  underwriting  discounts
        and commissions) being registered, all of which will be paid by American
        Tower:

               Securities and Exchange Commission fee............$      166,818
               New York Stock Exchange listing fee...............         1,500
               Accountants' fees and expenses....................       300,000
               Legal fees and expenses...........................       300,000
               Miscellaneous.....................................       231,682
                                                                 --------------
                   Total.........................................$    1,000,000
                                                                 ==============

        The foregoing, except for the SEC, NYSE and NASD fees, are estimated.

        Item 15. Indemnification of Directors and Officers.

              Section 145 of the DGCL provides,  in effect, that any person made
        a  party  to any  action  by  reason  of the  fact  that  he is or was a
        director,  officer,  employee or agent of ATC may and, in certain cases,
        must be  indemnified  by ATC  against,  in the case of a  non-derivative
        action,  judgments,  fines,  amounts paid in settlement  and  reasonable
        expenses  (including  attorney's  fees),  if in either type of action he
        acted in good faith and in a manner he  reasonably  believed to be in or
        not  opposed  to the  best  interests  of ATC and,  in a  non-derivative
        action, which involves a criminal  proceeding,  in which such person had
        no  reasonable   cause  to  believe  his  conduct  was  unlawful.   This
        indemnification does not apply, in a derivative action, to matters as to
        which it is adjudged  that the director,  officer,  employee or agent is
        liable to ATC,  unless upon court order it is determined  that,  despite
        such adjudication of liability,  but in view of all the circumstances of
        the  case,  he is  fairly  and  reasonably  entitled  to  indemnity  for
        expenses.

              Article XII of ATC's  By-Laws  provides  that ATC shall  indemnify
       each  person who is or was an officer or  director  of ATC to the fullest
       extent permitted by Section 145 of the DGCL.

              Article  Sixth  of  ATC's  Restated  Certificate  states  than  no
       director of ATC shall be personally liable to ATC or its stockholders for
       monetary  damages for breach of fiduciary duty as a director,  except for
       (i) breach of the director's duty of loyalty to ATC or its  stockholders,
       (ii) acts or  omissions  not in good faith or which  involve  intentional
       misconduct or knowing violation of law, (iii) liability under Section 174
       of the DGCL relating to certain unlawful dividends and stock repurchases,
       or (iv) any  transaction  from which the  director  derived  an  improper
       personal benefit.


        Item 16. Exhibits.

              Listed  below  are the  exhibits  which  are filed as part of this
        Registration  Statement on Form S-3 (according to the number assigned to
        them in Item 601 of Regulation S-K).

<TABLE>
<CAPTION>
        Exhibit   Description of Document                                         Exhibit File No.
        No.
<S>     <C>                                                                       <C>
        4.1       Indenture, by and between the Company and The Bank of New York
                  as Trustee, for the 6.25% Notes, dated as of October 4, 1999,
                  including form of 6.25% Note                                    Filed herewith as Exhibit 4.1


                                      II-1
<PAGE>

        4.2       Indenture by and between the Company and The Bank of New York
                  as Trustee, for the 2.25% Notes, dated as of October 4, 1999,
                  including the form of 2.25% Note.                               Filed herewith as Exhibit 4.2
        4.3       Form of 6.25% Note (included in Exhibit 4.1)                    Filed herewith as part of Exhibit 4.1
        4.4       Form of 2.25% Note (included in Exhibit 4.2)                    Filed herewith as part of Exhibit 4.2
        4.5       Registration Rights Agreement,  by and between the Company and
                  the Initial Purchasers named therein, dated as of October 4,
                  1999                                                            Filed herewith as Exhibit 4.5
        5         Opinion of Sullivan & Worcester LLP                             To be filed by amendment
        8         Tax Opinion of Sullivan & Worcester LLP                         To be filed by amendment
        12        Statement Regarding  Computation of Ratios of Earnings to
                  Fixed Charges                                                   Filed herewith as Exhibit 12
        23        Consent of Sullivan & Worcester LLP                             Contained in the opinion of Sullivan &
                                                                                  Worcester LLP filed herewith as part
                                                                                  of Exhibits 5 and 8
        23.1      Independent Auditors' Consent--Deloitte & Touche LLP            Filed herewith as Exhibit 23.1
        23.2      Consent of KPMG LLP                                             Filed herewith as Exhibit 23.2
        23.3      Consent of KPMG LLP                                             Filed herewith as Exhibit 23.3
        23.4      Consent of Ernst & Young LLP                                    Filed herewith as Exhibit 23.4
        23.5      Consent of Ernst & Young LLP                                    Filed herewith as Exhibit 23.5
        23.6      Consent of KPMG LLP                                             Filed herewith as Exhibit 23.6
        23.7      Consent of Arthur Andersen LLP                                  Filed herewith as Exhibit 23.7
        23.8      Consent of KPMG LLP                                             Filed herewith as Exhibit 23.8
        24        Power of Attorney                                               Filed herewith as page II-4 of the
                                                                                  Registration Statement
        25        Statement of Eligibility of Trustee on Form T-1                 Filed herewith as Exhibit 25
</TABLE>


        Item 17. Undertakings.

        (a)The undersigned Registrant hereby undertakes:

           (1) To file,  during  any  period in which  offers or sales are being
        made, a post-effective amendment to this registration statement:

                  (i) To include any prospectus  required by section 10(a)(3) of
                  the Securities Act of 1933;

                  (ii)To  reflect in the  prospectus any facts or events arising
                  after the effective date of the registration statement (or the
                  most   recent   post-effective   amendment   thereof)   which,
                  individually  or in the  aggregate,  represent  a  fundamental
                  change  in the  information  set  forth  in this  registration
                  statement.  Notwithstanding  the  foregoing,  any  increase or
                  decrease in volume of securities  offered (if the total dollar
                  value of  securities  offered  would not exceed that which was
                  registered)  and any deviation from the low or high end of the
                  estimated  maximum offering range may be reflected in the form
                  of  prospectus  filed  with the  Commission  pursuant  to Rule
                  424(b) under the  Securities Act of 1933 if, in the aggregate,
                  the changes in volume and price  represent  no more than a 20%
                  change in the maximum  aggregate  offering  price set forth in
                  the   "Calculation   of   Registration   Fee"  table  in  this
                  registration statement; and

                  (iii) To include any material  information with respect to the
                  plan  of  distribution   not  previously   disclosed  in  this
                  registration   statement  or  any  material   change  to  such
                  information in this registration statement;



                                      II-2
<PAGE>

       provided,   however,  that  the  undertakings  set  forth  in  paragraphs
       (a)(1)(i) and (a)(1)(ii) above do not apply if the registration statement
       is on Form S-3 or Form S-8, and the  information  required to be included
       in a  post-effective  amendment  by  those  paragraphs  is  contained  in
       periodic  reports  filed  with  or  furnished  to the  Commission  by the
       Registrant pursuant to Section 13 or 15(d) of the Securities Exchange Act
       of  1934  that  are  incorporated  by  reference  in  this   registration
       statement.

           (2) That,  for the purpose of  determining  any  liability  under the
       Securities  Act of 1933,  each  such  post-effective  amendment  shall be
       deemed to be a new  registration  statement  relating  to the  securities
       offered  therein,  and the offering of such securities at that time shall
       be deemed to be the initial bona fide offering thereof.

           (3)  To  remove  from  registration  by  means  of  a  post-effective
       amendment any of the securities  being  registered which remain unsold at
       the termination of the offering.

       (b) The undersigned  registrant  hereby  undertakes that, for purposes of
       determining  any liability  under the Securities Act of 1933, each filing
       of the  Registrant's  annual report pursuant to Section 13(a) or 15(d) of
       the Securities  Exchange Act of 1934 that is incorporated by reference in
       the  registration  statement  shall be  deemed  to be a new  registration
       statement relating to the securities offered therein, and the offering of
       such  securities at that time shall be deemed to be the initial bona fide
       offering thereof.

       (c)  Insofar  as  indemnification   for  liabilities  arising  under  the
       Securities  Act of 1933  may be  permitted  to  directors,  officers  and
       controlling persons of the Registrant pursuant to the provisions referred
       to  in  Item  15  of  this  registration  statement,  or  otherwise,  the
       Registrant  has been  advised that in the opinion of the  Securities  and
       Exchange  Commission  such  indemnification  is against  public policy as
       expressed in the Securities Act and is, therefore,  unenforceable. In the
       event that a claim for  indemnification  against such liabilities  (other
       than the  payment by the  Registrant  of  expenses  incurred or paid by a
       director,  officer  or  controlling  person  of  the  Registrant  in  the
       successful defense of any action, suit or proceeding) is asserted by such
       director, officer or controlling person in connection with the securities
       being  registered,  the  Registrant  will,  unless in the  opinion of its
       counsel the matter has been settled by controlling precedent, submit to a
       court   of   appropriate   jurisdiction   the   question   whether   such
       indemnification  by it is  against  public  policy  as  expressed  in the
       Securities  Act and will be  governed by the final  adjudication  of such
       issue.

       (d) The undersigned registrant hereby undertakes:

           (1) To file  an  application  for  the  purpose  of  determining  the
       eligibility of the trustee to act under  subsection (a) of Section 310 of
       the Trust  Indenture  Act in  accordance  with the rules and  regulations
       prescribed by the Commission under Section 305(b)(2) of the Act.

           (2)  That  for  purposes  of  determining  any  liability  under  the
       Securities  Act of  1933,  the  information  omitted  from  the  form  of
       Prospectus filed as part of this Registration  Statement in reliance upon
       Rule 430A and contained in a form of Prospectus  filed by the  Registrant
       pursuant to Rule  424(b)(1)  or (4) or 497(h)  under the  Securities  Act
       shall be deemed to be part of this Registration  Statement as of the time
       it was effective.

           (3) That for the  purpose  of  determining  any  liability  under the
       Securities  Act of 1933,  each  post-effective  amendment that contains a
       form of  Prospectus  shall be deemed to be a new  registration  statement
       relating to the  securities  offered  therein,  and the  offering of such
       securities  at that time shall be deemed to be initial bona fide offering
       thereof.



                                      II-3
<PAGE>

                                   SIGNATURES

       Pursuant to the  requirements  of the Securities Act of 1933, the Company
       certifies that it has reasonable  grounds to believe that it meets all of
       the  requirements  for  filing  on  Form  S-3 and has  duly  caused  this
       registration  statement  to be signed on its  behalf by the  undersigned,
       thereunto  duly  authorized,  in the  City  of  Boston,  Commonwealth  of
       Massachusetts, on the twentieth day of October, 1999.

                                        AMERICAN TOWER CORPORATION


                                        By:     /s/ Steven B Dodge
                                           -------------------------------------
                                                Steven B. Dodge
                                           Chairman  of the Board, President and
                                           Chief Executive Officer

       The undersigned Officers and Directors of American Tower Corporation (the
       "Company")  hereby  severally   constitute  Joseph  L.  Winn,  Justin  D.
       Benincasa, Jonathan Black and Norman A. Bikales, and each of them, acting
       singly,  our true and lawful attorneys to sign for us and in our names in
       the capacities  indicated below the Company's  Registration  Statement on
       Form S-3  relating  to the  registration  of such  securities  under  the
       Securities Act of 1933, as amended,  and any and all amendments  thereto,
       including without limitation any registration statement or post-effective
       amendment thereof filed under and meeting the requirements of rule 462(b)
       under the Securities Act, hereby  ratifying and confirming our signatures
       as they may be signed by our attorneys to such Registration Statement and
       any and all amendments thereto.

       Pursuant  to  the  requirements  of the  Securities  Act  of  1933,  this
       Registration  Statement has been signed below by the following persons on
       behalf of the Company and in the capacities and on the dates indicated.

<TABLE>
<CAPTION>
                      Signature                                    Title                              Date

<S>                                                <C>                                          <C>
                 /s/ Steven B. Dodge               Chairman, President, Chief Executive         October 20, 1999
                 Steven B. Dodge                   Officer and Director

                 /s/ Joseph L. Winn                Chief Financial Officer and                  October 20, 1999
                 Joseph L. Winn                    Treasurer

                 /s/ Justin D. Benincasa           Vice President and Corporate                 October 20, 1999
                 Justin D. Benincasa               Controller

                 /s/ Alan L. Box                   Executive Vice President and                 October 20, 1999
                 Alan L. Box                       Director

                 /s/ Arnold L. Chavkin             Director                                     October 20, 1999
                 Arnold L. Chavkin

                 /s/ Dean H. Eisner                Director                                     October 20, 1999
                 Dean H. Eisner


                                      II-4
<PAGE>


                 /s/ Jack D. Furst                 Director                                     October 20, 1999
                 Jack D. Furst

                 /s/ J. Michael Gearon, Jr.        Executive Vice President and                 October 20, 1999
                 J.Michael Gearon, Jr.             Director

                 /s/ Fred R. Lummis                Director                                     October 20, 1999
                 Fred R. Lummis

                 /s/ Randall Mays                  Director                                     October 20, 1999
                 Randall Mays

                 /s/ Thomas H. Stoner              Director                                     October 20, 1999
                 Thomas H. Stoner

                 /s/ Maggie Wilderotter            Director                                     October 20, 1999
                 Maggie Wilderotter
</TABLE>



                                      II-5
<PAGE>


                                  EXHIBIT INDEX

        Listed  below  are  the  exhibits  which  are  filed  as  part  of  this
        Registration  Statement on Form S-3 (according to the number assigned to
        them in Item 601 of Regulation S-K).

<TABLE>
<CAPTION>
        Exhibit   Description of Document                                         Exhibit File No.
        No.
        <S>       <C>                                                             <C>
        4.1       Indenture, by and between the Company and The Bank of New York
                  as Trustee, for the 6.25% Notes, dated as of October 4, 1999,
                  including form of 6.25% Note                                    Filed herewith as Exhibit 4.1
        4.2       Indenture by and between the Company and The Bank of New York
                  as Trustee, for the 2.25% Notes, dated as of October 4, 1999,
                  including the form of 2.25% Note.                               Filed herewith as Exhibit 4.2
        4.3       Form of 6.25% Note (included in Exhibit 4.1)                    Filed herewith as part of Exhibit 4.1
        4.4       Form of 2.25% Note (included in Exhibit 4.2)                    Filed herewith as part of Exhibit 4.2
        4.5       Registration Rights Agreement,  by and between the Company and
                  the Initial Purchasers named therein, dated as of October 4,
                  1999                                                            Filed herewith as Exhibit 4.5
        5         Opinion of Sullivan & Worcester LLP                             To be filed by amendment
        8         Tax Opinion of Sullivan & Worcester LLP                         To be filed by amendment
        12        Statement Regarding  Computation of Ratios of Earnings to Fixed
                  Charges                                                         Filed herewith as Exhibit 12
        23        Consent of Sullivan & Worcester LLP                             Contained in the opinion of Sullivan &
                                                                                  Worcester LLP filed herewith as part
                                                                                  of Exhibits 5 and 8
        23.1      Independent Auditors' Consent--Deloitte & Touche LLP            Filed herewith as Exhibit 23.1
        23.2      Consent of KPMG LLP                                             Filed herewith as Exhibit 23.2
        23.3      Consent of KPMG LLP                                             Filed herewith as Exhibit 23.3
        23.4      Consent of Ernst & Young LLP                                    Filed herewith as Exhibit 23.4
        23.5      Consent of Ernst & Young LLP                                    Filed herewith as Exhibit 23.5
        23.6      Consent of KPMG LLP                                             Filed herewith as Exhibit 23.6
        23.7      Consent of Arthur Andersen LLP                                  Filed herewith as Exhibit 23.7
        23.8      Consent of KPMG LLP                                             Filed herewith as Exhibit 23.8
        24        Power of Attorney                                               Filed herewith as page II-4 of the
                                                                                  Registration Statement
        25        Statement of Eligibility of Trustee on Form T-1                 Filed herewith as Exhibit 25
</TABLE>





                                                                     EXHIBIT 4.1



                           AMERICAN TOWER CORPORATION


                              THE BANK OF NEW YORK

                                     Trustee


                      ------------------------------------



                                    Indenture


                           Dated as of October 4, 1999

                      ------------------------------------


                                  $300,000,000


                   (subject to increase to up to $360,000,000
                         in the event and to the extent
                             an option is exercised)


                        6.25% Convertible Notes Due 2009


<PAGE>
<TABLE>
<CAPTION>


                                TABLE OF CONTENTS

                                                                                                      Page

<S>                                                                                                     <C>

PARTIES..................................................................................................1

RECITALS

         Authorization of Indenture .....................................................................1
         Compliance with Legal Requirements..............................................................1
         Purpose of and Consideration for Indenture......................................................1


                                   ARTICLE ONE

                                   DEFINITIONS

         SECTION 1.1  Certain Terms Defined..............................................................1
                  Affiliate..............................................................................2
                  Agent    ..............................................................................2
                  Board of Directors.....................................................................2
                  Board Resolution.......................................................................2
                  Business Day...........................................................................2
                  Capital Stock..........................................................................3
                  Cash Equivalents.......................................................................3
                  Change in Control......................................................................3
                  Change in Control Repurchase Date......................................................3
                  Change in Control Repurchase Price.....................................................3
                  Class A Common Stock...................................................................4
                  Closing Date...........................................................................4
                  Common Stock...........................................................................4
                  Conversion Agent.......................................................................4
                  Conversion Price.......................................................................4
                  Corporate Trust Office.................................................................4
                  Date of Conversion.....................................................................4
                  Depositary.............................................................................4
                  Disposition............................................................................4
                  DTC      ..............................................................................5
                  Equity Interests.......................................................................5
                  Event of Default.......................................................................5
                  Excess Amount..........................................................................5


                                       -i-



<PAGE>
                                                                                                      Page


                  Exchange Act...........................................................................5
                  Global Security........................................................................5
                  Holder   ..............................................................................5
                  Holder of Securities...................................................................5
                  Securityholder.........................................................................5
                  Immediate Family Member................................................................5
                  Indenture..............................................................................5
                  Issuer   ..............................................................................6
                  Issuer Notice..........................................................................6
                  Issuer Order...........................................................................6
                  Issuer Repurchase Notice...............................................................6
                  Issuer Repurchase Notice Date..........................................................6
                  Last Sale Price........................................................................6
                  NASDAQ   ..............................................................................7
                  Officer  ..............................................................................7
                  Officers' Certificate..................................................................7
                  Opinion of Counsel.....................................................................7
                  Outstanding............................................................................7
                  Paying Agent...........................................................................8
                  Permitted Owner........................................................................8
                  Person   ..............................................................................8
                  principal..............................................................................8
                  Principal Stockholders.................................................................8
                  Proceeding.............................................................................8
                  Redemption Date........................................................................9
                  Redemption Price.......................................................................9
                  Registrar..............................................................................9
                  Registration Right Agreement...........................................................9
                  Related Party..........................................................................9
                  Repurchase Date........................................................................9
                  Repurchase Price.......................................................................9
                  Responsible Officer....................................................................9
                  Restricted Global Security.............................................................9
                  Restricted Security...................................................................10
                  SEC      .............................................................................10
                  Security .............................................................................10
                  Securities............................................................................10
                  Securities Act........................................................................10
                  Subsidiary............................................................................10
                  Surviving Person......................................................................10



                                      -ii-



<PAGE>


                                                                                                      Page

                  TIA      .............................................................................10
                  Trading Day...........................................................................10
                  Trustee  .............................................................................11
                  U.S. Government Obligations...........................................................11


                                   ARTICLE TWO

                                   SECURITIES

         SECTION 2.1  Form and Dating...................................................................11
         SECTION 2.2  Execution and Authentication......................................................12
         SECTION 2.3  Registrar, Paying Agent and
                                    Conversion Agent....................................................14
         SECTION 2.4  Paying Agent to Hold Money in Trust...............................................15
         SECTION 2.5  Holder Lists  ....................................................................16
         SECTION 2.6  Transfer and Exchange.............................................................16
         SECTION 2.7  Replacement Securities............................................................17
         SECTION 2.8  Outstanding Securities............................................................17
         SECTION 2.9  Temporary Securities..............................................................18
         SECTION 2.10  Cancellation ....................................................................18
         SECTION 2.11  Defaulted Interest...............................................................19
         SECTION 2.12  CUSIP Numbers....................................................................19
         SECTION 2.13  Global Securities................................................................19
         SECTION 2.14  Transfer Restrictions............................................................22

                                  ARTICLE THREE

                                    COVENANTS

         SECTION 3.1  Payment of Principal and Interest.................................................23
         SECTION 3.2  Written Statement to Trustee......................................................23
         SECTION 3.3  Corporate Existence...............................................................24
         SECTION 3.4  Reports by the Issuer.............................................................24
         SECTION 3.5  Waiver of Usury Defense...........................................................25
         SECTION 3.6  Payment of Excess Cash Dividends..................................................25
         SECTION 3.7  Registration Rights...............................................................26

                                      -iii-



<PAGE>

                                                                                                      Page

                                  ARTICLE FOUR

                           REMEDIES OF THE TRUSTEE AND
                       SECURITYHOLDERS ON EVENT OF DEFAULT

         SECTION 4.1  Event of Default Defined;
                       Acceleration of Maturity; Waiver of
                                    Default.............................................................26
         SECTION 4.2  Collection of Indebtedness by
                                    Trustee; Trustee May Prove Debt.....................................29
         SECTION 4.3  Application of Proceeds...........................................................32
         SECTION 4.4  Suits for Enforcement.............................................................34
         SECTION 4.5  Restoration of Rights or Abandonment
                                    of Proceedings......................................................34
         SECTION 4.6  Limitations on Suits by
                                    Securityholders.....................................................34
         SECTION 4.7  Unconditional Right of
                                    Securityholders to Receive
                       Principal, Premium and Interest, to
                        Convert and to Institute Certain
                                    Suits...............................................................35
         SECTION 4.8  Powers and Remedies Cumulative; Delay
                                    or Omission Not Waiver of Default...................................36
         SECTION 4.9  Control by Securityholders........................................................36
         SECTION 4.10  Waiver of Past Defaults..........................................................37
         SECTION 4.11  Trustee to Give Notice of Default,
                                    But May Withhold in Certain
                                    Circumstances.......................................................37
         SECTION 4.12  Right of Court to Require Filing of
                                    Undertaking to Pay Costs............................................38
         SECTION 4.13  Waiver of Stay or Extension Laws.................................................39

                                  ARTICLE FIVE

                             CONCERNING THE TRUSTEE

         SECTION 5.1  Duties and Responsibilities of the
                        Trustee; During Default; Prior to
                                    Default.............................................................39


                                      -iv-



<PAGE>


                                                                                                      Page
         SECTION 5.2  Certain Rights of the Trustee.....................................................41
         SECTION 5.3  Trustee Not Responsible for Recitals,
                                    Disposition of Securities or
                                    Application of Proceeds Thereof.....................................43
         SECTION 5.4  Trustee and Agents May Hold
                                    Securities; Collections, etc........................................43
         SECTION 5.5  Compensation and Indemnification of
                                    Trustee and Its Prior Claim.........................................44
         SECTION 5.6  Right of Trustee to Rely on Officers'
                                    Certificate, etc....................................................45
         SECTION 5.7  Persons Eligible for Appointment as
                                    Trustee.............................................................45
         SECTION 5.8  Resignation and Removal; Appointment
                                    of Successor Trustee................................................46
         SECTION 5.9  Acceptance of Appointment by
                                    Successor Trustee...................................................48
         SECTION 5.10  Merger, Conversion, Consolidation or
                                    Succession to Business of Trustee...................................49

                                   ARTICLE SIX

                         CONCERNING THE SECURITYHOLDERS

         SECTION 6.1  Evidence of Action Taken by
                                    Securityholders.....................................................50
         SECTION 6.2  Proof of Execution of Instruments and
                                    of Holding of Securities............................................50
         SECTION 6.3  Holders to Be Treated as Owners...................................................50
         SECTION 6.4  Securities Owned by Issuer Deemed Not
                                    Outstanding.........................................................51
         SECTION 6.5  Right of Revocation of Action Taken...............................................52
         SECTION 6.6  Record Date for Consents and Waivers..............................................52

                                  ARTICLE SEVEN

                             SUPPLEMENTAL INDENTURES

         SECTION 7.1  Supplemental Indentures Without
                                    Consent of Securityholders..........................................53


                                       -v-



<PAGE>


                                                                                                      Page
         SECTION 7.2  Supplemental Indentures with Consent
                                    of Securityholders..................................................55
         SECTION 7.3  Effect of Supplemental Indenture..................................................57
         SECTION 7.4  Documents to be Given to Trustee..................................................57
         SECTION 7.5  Notation on Securities in Respect of
                                    Supplemental Indentures.............................................57

                                  ARTICLE EIGHT

                    CONSOLIDATION, MERGER, SALE OR CONVEYANCE

         SECTION 8.1  Covenant Not to Merge, Consolidate,
                         Sell or Convey Property Except
                                    Under Certain Conditions............................................57
         SECTION 8.2  Successor Corporation or Entity
                                    Substituted.........................................................58
         SECTION 8.3  Opinion of Counsel and Officers'
                                    Certificate to Trustee..............................................59


                                  ARTICLE NINE

                           SATISFACTION AND DISCHARGE
                         OF INDENTURE; UNCLAIMED MONEYS

         SECTION 9.1  Satisfaction and Discharge of
                                    Indenture...........................................................60
         SECTION 9.2  Application by Trustee of Funds
                                    Deposited for Payment of
                                    Securities..........................................................61
         SECTION 9.3  Repayment of Moneys Held by Paying
                                    Agent...............................................................62
         SECTION 9.4  Return of Moneys Held by Trustee and
                         Paying Agent Unclaimed for Two
                                    Years...............................................................62
         SECTION 9.5  Indemnity for U.S. Government
                                    Obligations.........................................................63



                                      -vi-



<PAGE>


                                                                                                      Page
                                   ARTICLE TEN

                            MISCELLANEOUS PROVISIONS

         SECTION 10.1  Partners, Incorporators,
                                    Stockholders, Officers and
                         Directors of Issue Exempt from
                                    Individual Liability................................................63
         SECTION 10.2  Provisions of Indenture for the Sole
                                    Benefit of Parties and
                                    Securityholders.....................................................63
         SECTION 10.3  Successors and Assigns of Issuer
                                    Bound by Indenture..................................................63
         SECTION 10.4  Notices and Demands on Issuer,
                                    Trustee and Securityholders.........................................64
         SECTION 10.5  Officers' Certificates and Opinions
                                    of Counsel; Statements to Be
                                    Contained Therein...................................................65
         SECTION 10.6  Payments Due on Saturdays, Sundays
                                    and Legal Holidays..................................................66
         SECTION 10.7  Conflict with TIA................................................................67
         SECTION 10.8  Communications by Holders with Other
                                    Holders.............................................................67
         SECTION 10.9  Issuer to Furnish Trustee Names and
                                    Addresses of Holders................................................67
         SECTION 10.10  New York Law to Govern..........................................................67
         SECTION 10.11  Counterparts....................................................................68
         SECTION 10.12  Effect of Headings..............................................................68

                                 ARTICLE ELEVEN

                            REDEMPTION OF SECURITIES

         SECTION 11.1  Right of Optional Redemption;
                                    Prices..............................................................68
         SECTION 11.2  Notice of Redemption; Partial
                                    Redemptions.........................................................68
         SECTION 11.3  Payment of Securities Called for
                                    Redemption..........................................................70

                                      -vii-



<PAGE>


                                                                                                      Page
         SECTION 11.4  Exclusion of Certain Securities from
                          Eligibility for Selection for
                                    Redemption..........................................................71
         SECTION 11.5  Conversion Arrangement on Call for
                                    Redemption..........................................................72

                                 ARTICLE TWELVE

                            CONVERSION OF SECURITIES

         SECTION 12.1  Conversion Privilege.............................................................73
         SECTION 12.2  Exercise of Conversion Privilege.................................................74
         SECTION 12.3  Fractional Shares................................................................76
         SECTION 12.4  Adjustment of Conversion Price...................................................76
         SECTION 12.5  Continuation of Conversion Privilege
                                    in Case of Reclassification,
                         Reorganization, Change, Merger,
                                    Consolidation or Sale of Assets.....................................81
         SECTION 12.6  Notice of Certain Events.........................................................82
         SECTION 12.7  Taxes on Conversion..............................................................83
         SECTION 12.8  Issuer to Provide Class A Common
                                    Stock...............................................................84
         SECTION 12.9  Disclaimer of Responsibility for
                                    Certain Matters.....................................................85
         SECTION 12.10  Return of Funds Deposited for
                                    Redemption of Converted Securities..................................86


                                ARTICLE THIRTEEN

               RIGHT TO REQUIRE REDEMPTION UPON CHANGE IN CONTROL

         SECTION 13.1  Right to Require Redemption......................................................86
         SECTION 13.2  Notices; Method of Exercising
                                    Redemption Right, etc...............................................87
         SECTION 13.3  Definition of Change in Control..................................................89
         SECTION 13.4  Limitation on Right to Require
                                    Redemption..........................................................90


                                     -viii-


<PAGE>

                                ARTICLE FOURTEEN

                REPURCHASE OF SECURITIES AT OPTION OF THE HOLDER

         SECTION 14.1  General      ....................................................................91
         SECTION 14.2  Issuer's Right to Elect Manner of
                                    Payment of Repurchase Price.........................................93
         SECTION 14.3  Repurchase with Cash.............................................................94
         SECTION 14.4  Payment by Issuance of Class A
                                    Common Stock........................................................94
         SECTION 14.5  Notice of Election...............................................................97
         SECTION 14.6  Covenants of the Issuer..........................................................99
         SECTION 14.7  Procedure upon Repurchase........................................................99
         SECTION 14.8  Taxes        ...................................................................100
         SECTION 14.9  Effect of Repurchase Notice.....................................................100
         SECTION 14.10  Deposit of Repurchase Price....................................................102
         SECTION 14.11  Securities Repurchased in Part.................................................102
         SECTION 14.12  Issuer to Comply with Securities
                                    Laws Upon Purchase of Securities...................................103
         SECTION 14.13  Repayment to the Issuer........................................................103

SIGNATURES                 ............................................................................104

EXHIBIT A -- FORM OF SECURITY
</TABLE>

                                      -ix-

<PAGE>



                  THIS INDENTURE,  dated as of October 4, 1999 between  American
Tower Corporation,  a Delaware  corporation (the "Issuer"),  and The Bank of New
York, a New York banking corporation (the "Trustee"),

                              W I T N E S S E T H :

                  WHEREAS, the Issuer has duly authorized the issue of its 6.25%
Convertible  Notes Due 2009 (the  "Securities") of  substantially  the tenor and
amount hereinafter set forth;

                  WHEREAS,  the Issuer has duly  authorized  the  execution  and
delivery  of  this   Indenture  to  provide,   among  other   things,   for  the
authentication, delivery and administration of the Securities; and

                  WHEREAS,  all things  necessary to make this Indenture a valid
indenture and agreement according to its terms have been done;

                  NOW, THEREFORE:

                  In  consideration  of the  premises  and the  purchases of the
Securities by the Holders thereof,  the Issuer and the Trustee mutually covenant
and agree for the equal and proportionate benefit of the respective Holders from
time to time of the Securities as follows:


                                   ARTICLE ONE

                                   DEFINITIONS

                  SECTION 1.1 Certain Terms Defined. The following terms (except
as  otherwise  expressly  provided  or  unless  the  context  otherwise  clearly
requires) for all purposes of this  Indenture and of any indenture  supplemental
hereto shall have the respective  meanings specified in this Section.  All other
terms used in this Indenture which are defined in the TIA, or the definitions of
which  in the  Securities  Act are  referred  to in the TIA  (except  as  herein
otherwise  expressly provided or unless the context otherwise  requires),  shall


<PAGE>


have the meaning  assigned to such terms in the TIA and the Securities Act as in
force at the date of this  Indenture.  All accounting  terms used herein and not
expressly  defined  shall have the  meanings  given to them in  accordance  with
generally  accepted  accounting  principles,  and the term  "generally  accepted
accounting principles" shall mean such accounting principles which are generally
accepted at the date or time of any  computation.  The words "herein",  "hereof"
and  "hereunder"  and other words of similar import refer to this Indenture as a
whole and not to any particular Article, Section or other subdivision. The terms
defined in this Article include the plural as well as the singular.

                  "Affiliate"  of any  specified  Person  means any other Person
directly or indirectly  controlling or controlled by or under direct or indirect
common control with such specified Person.  For the purposes of this definition,
"control"  when used with  respect to any  specified  Person  means the power to
direct the  management  and  policies of such  Person,  directly or  indirectly,
whether  through the ownership of voting  securities,  by contract or otherwise;
and the terms  "controlling" and "controlled"  have meanings  correlative to the
foregoing.

                  "Agent" means any Registrar, Paying Agent or Conversion Agent.

                  "Board of  Directors"  means  either the Board of Directors of
the Issuer or any committee of such Board duly authorized to act on its behalf.

                  "Board  Resolution"  means a copy of one or more  resolutions,
certified by the secretary or an assistant  secretary of the Issuer to have been
duly adopted by the Board of Directors and to be in full force and effect on the
date of such certification, and delivered to the Trustee.

                  "Business  Day" means a day which in the City and State of New
York is neither  Saturday,  Sunday,  a legal  holiday nor a day on which banking
institutions  and  trust  companies  are  authorized  by  law or  regulation  or
executive order to close.

                                      -2-
<PAGE>

                  "Capital  Stock"  means  (i) in  the  case  of a  corporation,
capital stock,  (ii) in the case of any association or business entity,  any and
all shares,  interests,  participations,  rights or other  equivalents  (however
designated) or capital stock and (iii) in the case of a partnership, partnership
interests  (whether  general or limited) and any other interest or participation
that  confers on a Person the right to receive a share of the profits and losses
of, or distributions of assets of, such partnership.

                  "Cash  Equivalents"  means (i)  United  States  dollars,  (ii)
securities  issued or  directly  and fully  guaranteed  or insured by the United
States government or any agency or instrumentality  thereof having maturities of
less than one year from the date of acquisition,  (iii)  certificates of deposit
and eurodollar time deposits with maturities of less than one year from the date
of acquisition,  bankers'  acceptances with maturities of less than one year and
overnight  bank  deposits,  in each case  with any  lender  party to the  Credit
Agreements or with any domestic  commercial  bank having  capital and surplus in
excess of  $500,000,000  and a Keefe  Bank Watch  Rating of "B" or better,  (iv)
repurchase  obligations  with a term of not more than seven days for  underlying
securities  of the types  described in clauses (ii) and (iii)  entered into with
any financial  institution meeting the qualifications  specified in clause (iii)
above and (v) commercial paper having the highest rating obtainable from Moody's
Investors Service, Inc. or Standard & Poor's Ratings Services, a division of the
McGraw-Hill Companies,  Inc., and in each case maturing within nine months after
the date of acquisition.

                  "Change in Control" has the meaning  assigned to it in Section
13.3.

                  "Change in Control  Repurchase  Date" has the meaning assigned
to it in Section 13.1.

                  "Change in Control  Repurchase Price" has the meaning assigned
to it in Section 13.1.

                                      -3-
<PAGE>

                  "Class A Common  Stock"  means the Class A Common  Stock,  par
value $0.01 per share,  of the Issuer as the same exists at the Closing  Date or
as such stock may be reconstituted from time to time.

                  "Closing  Date"  means  the date (or,  if more  than one,  the
earliest date) of original issuance of the Securities.

                  "Common  Stock"  means the Class A Common  Stock,  the Class B
Common Stock,  par value $0.01 per share and the Class C Common Stock, par value
$0.01 per share, of the Issuer as the same exists at the Closing Date or as such
stock may be reconstituted from time to time.

                  "Conversion  Agent" has the meaning  assigned to it in Section
2.3.

                  "Conversion   Price"  means  the   principal   amount  of  the
Securities  convertible  into one  share of Class A  Common  Stock,  subject  to
adjustment in accordance with Section 12.4.

                  "Corporate  Trust  Office"  means the office of the Trustee at
which the corporate trust business of the Trustee shall, at any particular time,
be  principally  administered,  which  office  is, at the date as of which  this
Indenture is dated, located at 101 Barclay Street, 21W, New York, NY 10286.

                  "Date of Conversion" has the meaning assigned to it in Section
12.2.

                  "Depositary"  means  with  respect to  Securities,  a clearing
agency that is  registered  as such under the Exchange Act and is  designated by
the Issuer to act as Depositary for such Securities (or any successor securities
clearing agency so registered.)

                  "Disposition" has the meaning assigned to it in Section 8.1.

                                      -4-
<PAGE>

                  "DTC"  means  The  Depository   Trust  Company,   a  New  York
corporation.

                  "Equity  Interests"  means  Capital  Stock  and all  warrants,
options or other rights to acquire Capital Stock  (including any securities that
is convertible into, or exchangeable for, Capital Stock).

                  "Event of Default"  means any event or condition  specified as
such in Section 4.1.

                  "Excess Amount" has the meaning assigned to it in Section 3.6.

                  "Exchange Act" means the  Securities  Exchange Act of 1934, as
amended.

                  "Global  Security"  means a Security that is registered in the
security register kept by the Registrar in the name of a Depositary or a nominee
thereof.

                  "Holder",  "Holder of Securities",  "Securityholder"  or other
similar  terms mean in the case of any  Security,  the Person in whose name such
Security is registered  in the security  register kept by the Registrar for that
purpose in accordance with the terms hereof.

                  "Immediate   Family  Member"   means,   with  respect  to  any
individual, such individual's spouse (past or current),  descendants (natural or
adoptive,  of the whole or half blood) of the parents of such  individual,  such
individual's   grandparents   and  parents   (natural  or  adoptive),   and  the
grandparents,  parents and descendants of parents  (natural or adoptive,  of the
whole or half blood) of such individual's spouse (past or current).

                  "Indenture"  means this instrument as originally  executed and
delivered or, if amended or  supplemented as herein  provided,  as so amended or
supplemented.

                                      -5-
<PAGE>

                  "Issuer"  means  American   Tower   Corporation,   a  Delaware
corporation, and, subject to Article Eight, its successors and assigns.

                  "Issuer  Notice"  has the  meaning  assigned  to it in Section
13.2.

                  "Issuer Order" means a written statement,  request or order of
the  Issuer  which  is  signed  in its  name by its  Chairman  of the  Board  of
Directors,  its  Chief  Executive  Officer,  its  President,  a Chief  Operating
Officer,  a Vice  President,  or  its  Chief  Financial  Officer,  and,  without
duplication,  by its Treasurer,  an Assistant  Treasurer,  its  Controller,  its
Secretary  or an  Assistant  Secretary,  of the  Issuer,  and  delivered  to the
Trustee.

                  "Issuer  Repurchase  Notice" has the meaning assigned to it in
Section 14.5.

                  "Issuer Repurchase Notice Date" has the meaning assigned to it
in Section 14.3.

                  "Last Sale  Price" on any day means the last sale price of the
Class A Common  Stock  as  reported  on the  composite  tape for New York  Stock
Exchange  listed  stocks  (or if not  listed  or  admitted  to  trading  on such
exchange,  then on the principal national securities exchange on which the Class
A Common  Stock is listed or admitted to trading,  or, if not listed or admitted
to  trading  on  any  national  securities  exchange,  on  NASDAQ  or a  similar
organization if NASDAQ is no longer reporting information) on such day or, if no
such sale takes place on such day, the last sale price for such day shall be the
average of the  closing bid and asked  prices  regular way on the New York Stock
Exchange (or, if not listed or admitted to trading on such exchange, then on the
principal  national  securities  exchange  on which the Class A Common  Stock is
listed or admitted  to trading,  or, if not listed or admitted to trading on any
national securities  exchange,  on NASDAQ or a similar organization if NASDAQ is
no longer reporting information) on such day.

                                      -6-
<PAGE>

                  "NASDAQ" means the National  Association of Securities Dealers
Automated Quotations National Market System.

                  "Officer"  means the Chairman of the Board of  Directors,  the
Chief  Executive  Officer,  the President,  a Chief  Operating  Officer,  a Vice
President,  the Chief Financial Officer, the Treasurer,  an Assistant Treasurer,
the Controller, the Secretary or an Assistant Secretary, of the Issuer.

                  "Officers'  Certificate"  means a  certificate  signed  by the
Chairman of the Board of Directors,  the Chief Executive Officer, the President,
a Chief Operating Officer, a Vice President, or the Chief Financial Officer and,
without duplication,  by the Treasurer, an Assistant Treasurer,  Controller, the
Secretary  or an  Assistant  Secretary,  of the  Issuer,  and  delivered  to the
Trustee.  Each such  certificate  shall include the  statements  provided for in
Section 10.5, if and to the extent required hereby.

                  "Opinion  of  Counsel"  means a written  opinion,  in form and
substance reasonably satisfactory to the Trustee, of counsel, who may be counsel
to the Issuer and who shall be  acceptable  to the  Trustee.  Each such  opinion
shall include the statements  provided for in Section 10.5, if and to the extent
required hereby.

                  "Outstanding",  when used with reference to Securities, shall,
subject to the provision of Section 6.4,  mean, as of any  particular  time, all
Securities  authenti  cated and delivered by the Trustee  under this  Indenture,
except

                  (a)  Securities   theretofore  cancelled  by  the  Trustee  or
         delivered to the Trustee for cancellation;

                  (b)  Securities,  or  portions  thereof,  for the  payment  or
         redemption  of which  moneys in the  necessary  amount  shall have been
         deposited  in trust with the  Trustee or with any Paying  Agent  (other
         than the Issuer) or shall have been set aside,  segregated  and

                                      -7-
<PAGE>

         held in trust by the Issuer (if the Issuer  shall act as its own Paying
         Agent),  provided that if such  Securities  are to be redeemed prior to
         the maturity  thereof,  notice of such redemption shall have been given
         as herein provided, or provision satisfactory to the Trustee shall have
         been made for giving such notice; and

                  (c)  Securities  in  substitution  for which other  Securities
         shall have been  authenticated and delivered,  or which shall have been
         paid,  pursuant to the terms of Section 2.7 (unless proof  satisfactory
         to the Trustee is presented  that any of such  Securities  is held by a
         Person in whose  hands  such  Security  is a legal,  valid and  binding
         obligation  of the Issuer),  Securities  converted  into Class A Common
         Stock pursuant hereto and Securities not deemed Outstanding pursuant to
         and for the purposes of the last sentence of Section 11.2.

                  "Paying Agent" has the meaning assigned to it in Section 2.3.

                  "Permitted  Owner" has the  meaning  assigned to it in Section
13.3.

                  "Person"  means any  individual,  corporation,  part  nership,
limited  liability  company,  joint venture,  association,  joint stock company,
trust,  unincorporated  organization  or  government  or any agency or political
subdivision thereof.

                  "principal"  wherever used with reference to the Securities or
any Security or any portion thereof shall be deemed to include "and premium,  if
any" whether or not so specified.  (Reference  is also made to Sections  13.2(c)
and 14.9.)

                  "Principal  Stockholders"  has the  meaning  assigned to it in
Section 13.3.

                  "Proceeding" has the meaning assigned to it in Section 12.2.

                                      -8-
<PAGE>

                  "Redemption  Date",  has the meaning assigned to it in Section
11.2.

                  "Redemption  Price", when used with respect to any Security to
be  redeemed,  means the price at which it is to be  redeemed  pursuant  to this
Indenture.

                  "Registrar" has the meaning assigned to it in Section 2.3.

                  "Registration  Right Agreement" means the Registration  Rights
Agreement,  dated as of  October  4,  1999,  among the  Issuer  and the  initial
purchasers named therein.

                  "Related  Party" with respect to any individual  means (i) any
Immediate   Family  Member  of  such   individual   or  (ii)  any  Person,   the
beneficiaries, stockholders, partners, owners or Persons beneficially holding an
80% or more  controlling  interest  of which  consist of such  individual  or an
Immediate Family Member.

                  "Repurchase  Date" has the  meaning  assigned to it in Section
14.1.

                  "Repurchase  Price" has the meaning  assigned to it in Section
14.1.

                  "Responsible  Officer",  when used with respect to the Trustee
means  any  officer  within  the  corporate  trust  department  of the  Trustee,
including any vice  president,  assistant vice president,  assistant  secretary,
assistant  treasurer,  trust  officer  or  any  other  officer  of  the  Trustee
customarily  performing  corporate trust functions similar to those performed by
the Persons who at the time shall be such officers, respectively, or to whom any
corporate  trust matter is referred  because of such  Person's  knowledge of and
familiarity with the particular subject and who shall have direct responsibility
for the administration of this Indenture.

                  "Restricted Global Security" has the meaning assigned to it in
Section 2.1.

                                      -9-
<PAGE>

                  "Restricted  Security"  means any Security  issued in exchange
for an  interest  in the  Restricted  Global  Security  until  such  time as the
Restricted  Security legend contemplated in Section 2.14 need not be provided on
the Security.

                  "SEC" means the  Securities  and  Exchange  Commission  or any
successor agency.

                  "Security" or "Securities" has the meaning stated in the first
recital  of  this   Indenture  and  more   particularly   means  any  securities
authenticated and delivered under this Indenture.

                  "Securities Act" means the Securities Act of 1933, as amended.

                  "Subsidiary"   means,   with   respect  to  any  Person,   any
corporation,  association or other business entity of which more than 50% of the
total  voting  power  of  Equity  Interests  entitled  (without  regard  to  the
occurrence of any contingency) to vote in the election of directors, managers or
trustees or other  governing  body thereof is at the time owned or controlled by
such Person  (regardless of whether such Equity  Interests are owned directly or
through one or more other Subsidiaries of such Person or a combination thereof).

                  "Surviving  Person" means, with respect to any Person involved
in or that  makes  any  Disposition,  the  Person  formed by or  surviving  such
Disposition or the Person to which such Disposition is made.

                  "TIA"  (except as otherwise  provided in Sections 7.1 and 7.2)
means the Trust  Indenture  Act of 1939 as in force at the date as of which this
Indenture was originally issued.

                  "Trading Day" means each Monday, Tuesday, Wednesday,  Thursday
and  Friday,  other  than  any day on which  securities  are not  traded  on the
applicable securities exchange or in the applicable securities market.

                                      -10-
<PAGE>

                  "Trustee"  means the entity  identified  as  "Trustee"  in the
first  paragraph  hereof and,  subject to the provisions of Article Five,  shall
also include any successor  trustee.  "Trustee"  shall also mean or include each
Person  who is then a trustee  hereunder  if at any time  there is more than one
such Person.

                  "U.S. Government Obligations" means direct obliga tions of the
United States of America, backed by its full faith and credit.


                                   ARTICLE TWO

                                   SECURITIES

                  SECTION 2.1 Form and Dating.  The Securities and the Trustee's
certificate of  authentication  shall be  substantially in the form of Exhibit A
(including the legends appearing  thereon),  the terms of which are incorporated
in and made a part of this Indenture. The Securities may have notations, legends
or endorsements  required by law,  securities exchange (including NASDAQ) rules,
agreements  to which the Issuer is subject or usage,  including,  if required by
Section 2.13,  the legend contem  plated  thereby.  The Issuer shall approve the
form of the  Securities and any notation,  legend or  endorsement on them.  Each
Security shall be dated the date of its authentication.

                  Upon their original  issuance,  Securities  shall be issued in
the form of one or more Global Securities  without interest coupons and shall be
registered in the name of DTC, as Depositary,  or its nominee and deposited with
the Trustee,  as custodian for DTC, for credit by DTC to the respective accounts
of  beneficial  owners of the  Securities  represented  thereby  (or such  other
accounts  as  they  may  direct).   Such  Global   Security  or  Securities  are
collectively  herein called the  "Restricted  Global  Security".  The Restricted
Global  Security and any  Restricted  Security  shall bear a different  CUSIP or
other  identifying  number from any  Security  that is not a  Restricted  Global
Security or Restricted Security.


                                      -11-
<PAGE>


                  SECTION 2.2 Execution and  Authentication.  Two Officers shall
sign the  Securities  for the  Issuer  by  manual or  facsimile  signature.  The
Issuer's seal shall be reproduced on the Securities.

                  If an Officer whose signature is on a Security no longer holds
that office at the time the Trustee  authenticates  the  Security,  the Security
shall be valid nevertheless.

                  A security shall not be valid until the Trustee manually signs
the certificate of authentication on the Security.  The signature of the Trustee
shall be conclusive evidence that the Security has been authenticated under this
Indenture.

                  The Trustee shall  authenticate  Securities for original issue
in the  aggregate  principal  amount  of  $300,000,000  upon  an  Issuer  Order;
provided,  however,  that if the Issuer  sells any  Securities  pursuant  to the
option in the Purchase  Agreement,  dated September 28, 1999, between the Issuer
and the initial  purchasers named therein,  then the Trustee shall  authenticate
Securities  for  original  issue  in the  aggregate  principal  amount  of up to
$360,000,000  upon an Issuer Order. The Issuer Order shall specify the amount of
Securities  to be  authenticated  and the date on which  the  original  issue of
Securities is to be authenticated.  The aggregate principal amount of Securities
outstanding  at any time may not exceed  the  amount  set forth in the  previous
sentence except as provided in Section 2.7.

                  The Trustee's  authentication  of  Securities  pursuant to the
next  preceding  paragraph  shall be  conditioned  upon  receipt  of each of the
following in form and  substance  reasonably  satisfactory  to the Trustee on or
prior to the Closing Date:

                  A.  An Officer's Certificate to the effect that:

                           (1) All  conditions  required to be  satisfied  under
                  this Indenture for the issuance of the

                                      -12-
<PAGE>

                  Securities  have been so  satisfied on or prior to the Closing
                  Date; and

                           (2) No Event of Default  shall have  occurred  and be
                  continuing.

                  B. An Opinion of Counsel to the effect that:

                           (1) The execution and delivery of the Indenture,  the
                  issuance of the  Securities  and the  fulfillment of the terms
                  herein and therein  contemplated  will not  conflict  with the
                  charter or bylaws of the Issuer,  or constitute a breach of or
                  default under any material agreement,  indenture,  evidence of
                  indebtedness,  mortgage,  deed  of  trust  or  other  material
                  agreement  or  instrument  known to such  counsel to which the
                  Issuer  is a  party  or by  which  it is  bound,  or any  law,
                  administrative  regulation,  rule,  judgment,  order or decree
                  known to such counsel to be applicable to the Issuer or any of
                  its properties;

                           (2) The  Indenture  has been duly  authorized  by the
                  Issuer,  executed and delivered by the Issuer, and is a legal,
                  valid and  binding  agree  ment of the Issuer  enforceable  in
                  accordance with its terms,  except as such  enforceability may
                  be  limited   by   bankruptcy,   insolvency,   reorganization,
                  receivership,  moratorium  and  similar  laws  affect  ing the
                  rights and remedies of creditors  and  obligations  of debtors
                  generally  and by the effect of general  principles of equity,
                  whether applied by a court of law or equity;

                           (3) All legally required proceedings by the Issuer in
                  connection  with  the   authorization  and  issuances  of  the
                  Securities have been duly taken,  and all orders,  consents or
                  other  authorizations or approvals of any public board or body
                  legally  required for the validity of the Securities have been
                  obtained; and

                                      -13-
<PAGE>

                           (4) The Securities,  when executed and  authenticated
                  in accordance  with the terms of this  Indenture and delivered
                  upon  payment  therefor,  will be  legal,  valid  and  binding
                  obligations of the Issuer enforceable in accordance with their
                  terms,  except  as  such  enforceability  may  be  limited  by
                  bankruptcy,    insolvency,    reorganization,    receivership,
                  moratorium  and similar laws affecting the rights and remedies
                  of creditors and  obligations of debtors  generally and by the
                  effect of general  principles of equity,  whether applied by a
                  court of law or equity.

                  The Trustee may appoint an authenticating  agent acceptable to
the  Issuer  to  authenticate  Securities.  Unless  limited  by the term of such
appointment,  an authenticating  agent may authenticate  Securities whenever the
Trustee may do so. Each  reference in this  Indenture to  authentication  by the
Trustee includes  authentication by such agent. An authenticating  agent has the
same rights as an Agent to deal with the Issuer or an Affiliate of the Issuer.

                  The  Securities  shall be  issuable  only in regis  tered form
without coupons and only in  denominations  of $1,000 and any integral  multiple
thereof.

                  SECTION 2.3 Registrar, Paying Agent and Conver sion Agent. The
Issuer shall  maintain in The Borough of Manhattan in The City of New York,  New
York, an office or agency where  Securities may be presented for registration of
transfer or for exchange ("Registrar"), an office or agency where Securities may
presented for payment and repurchase ("Paying Agent"), an office or agency where
Securities may be presented for conversion ("Conversion Agent") and an office or
agency  where  notices  and  demands  to or upon the  Issuer in  respect  of the
Securities and this Indenture may be served. The Registrar shall keep a register
of the Securities and of their transfer and exchange. The Issuer may appoint one
or more  co-Registrars,  one or more  additional  Paying  Agents and one or more
additional  Conversion  Agents,  which may be inside or outside  The  Borough of
Manhattan.  The term  "Registrar"  includes any  co-

                                      -14-
<PAGE>

Registrar,  the term "Paying Agent" includes any additional Paying Agent and the
term "Conversion Agent" includes any additional Conversion Agent. The Issuer may
change any  Registrar,  Paying Agent or Conversion  Agent without  notice to any
Holder.  If the Issuer fails to appoint or maintain another person as Registrar,
Paying Agent or Conversion  Agent,  the Trustee shall act as such. The Issuer or
any Affiliate of the Issuer may act as Registrar or Conversion Agent. Except for
purposes of Article  Nine,  the Issuer or any Affiliate of the Issuer may act as
Paying Agent.

                  The Issuer shall enter into an  appropriate  agency  agreement
with any Agent not a party to this Indenture.  The agreement shall implement the
provisions  of this  Indenture  that  relate to such  Agent.  The  Issuer  shall
promptly  notify the Trustee of the name and address of any Agent not a party to
this  Indenture.  If the Issuer  fails to maintain a  Registrar,  Paying  Agent,
Conversion  Agent or agent for service of notices and demands,  or fails to give
the foregoing notice, the Trustee shall act as such.

                  The Issuer initially appoints the Trustee as Registrar, Paying
Agent, Conversion Agent and agent for service of notices and demands.

                  SECTION  2.4 Paying  Agent to Hold  Money in Trust.  Not later
than 11:00 a.m.,  Eastern Standard Time, on each due date of the principal of or
interest on any Securities, the Issuer shall deposit with the Paying Agent a sum
of money in  immediately  available  funds  sufficient to pay such  principal or
interest so becoming due. Subject to Section 9.2, the Paying Agent shall hold in
trust for the  benefit of  Securityholders  or the Trustee all money held by the
Paying Agent for the payment of principal of or interest on the Securities,  and
shall  notify the  Trustee in writing of any default by the Issuer in making any
such payment.  If the Issuer or an Affiliate of the Issuer acts as Paying Agent,
it shall on or  before  each due date of the  principal  of or  interest  on any
Securities  segregate the money and hold it as a separate trust fund. The Issuer
at any  time may  require  a Paying  Agent  to pay all  money  held by it to the
Trustee,  and the Trustee may at any time during the

                                      -15-
<PAGE>

continuance of any default, upon written request to a Paying Agent, require such
Paying Agent to  forthwith  pay to the Trustee all sums so held in trust by such
Paying Agent. Upon doing so, the Paying Agent (other than the Issuer) shall have
no further liability for the money.

                  SECTION 2.5 Holder  Lists.  The Trustee  shall  preserve in as
current a form as is reasonably practicable the most recent list available to it
of the names and addresses of the Holders.  If the Trustee is not the Registrar,
the Issuer  shall  promptly  furnish to the Trustee on or before  each  interest
payment  date and at such other  times as the  Trustee  may request in writing a
list in such form and as of such date as the Trustee may reasonably  require for
the names and addresses of the Holders.

                  SECTION  2.6  Transfer  and  Exchange.   When  a  Security  is
presented to the Registrar  with a request to register a transfer  thereof,  the
Registrar shall register the transfer as requested, and, when Securities are
presented  to the  Registrar  with a  request  to  exchange  them  for an  equal
principal amount of Securities of other authorized denominations,  the Registrar
shall make the exchange as requested;  provided that every Security presented or
surrendered  for  registration of transfer or exchange shall be duly endorsed or
be accompanied by a written  instrument of transfer in form  satisfactory to the
Issuer and the  Registrar  duly  executed by the Holder  thereof or his attorney
duly authorized in writing.  To permit  registration of transfers and exchanges,
the Issuer shall  execute and the Trustee shall  authenticate  Securities at the
Issuer's  request.  The Issuer shall not be required (i) to issue,  register the
transfer of or exchange  Securities  during a period beginning at the opening of
business on a Business Day 15 days before the day of any selection of Securities
for redemption under Section 11.2 and ending at the close of business on the day
of  selection,  or (ii) to register  the transfer of or exchange any Security so
selected for redemption in whole or in part,  except the  unredeemed  portion of
any Security  being  redeemed in part. Any exchange or transfer shall be without
charge,  except that the Issuer may require payment of a sum sufficient to

                                      -16-
<PAGE>

cover any tax or other  governmental  charge  that may be  imposed  in  relation
thereto,  but this provision shall not apply to any exchange pursuant to Section
7.5 or 11.2.  Prior to due  presentment  for  registration  of  transfer  of any
Security, the Trustee, any Agent and the Issuer may deem and treat the Person in
whose name any Security is registered as the absolute owner of such Security for
the purpose of receiving  payment of principal of and interest on such  Security
and for all other purposes whatsoever,  whether or not such Security is overdue,
and none of the Trustee,  any Agent or the Issuer shall be affected by notice to
the contrary.

                  SECTION 2.7 Replacement Securities. If a mutilated Security is
surrendered  to the  Trustee,  or if the  Holder of a Security  claims  that the
Security has been lost,  destroyed or wrongfully  taken,  and neither the Issuer
nor the Trustee has received written notice that such Security has been acquired
by a bona  fide  purchaser,  the  Issuer  shall  issue  and  the  Trustee  shall
authenticate a replacement  Security if the requirements of Section 8-405 of the
New York Uniform  Commercial  Code, as in effect on the date of this  Indenture,
are met,  and there  shall have been  delivered  to the  Issuer and the  Trustee
evidence to their satisfaction of the loss, destruction or theft of any Security
if such is the case.  An indemnity  bond will be required  that is sufficient in
the judgment of the Issuer and the Trustee to protect the Issuer, the Trustee or
any Agent from any loss which any of them may suffer if a Security is  replaced.
The  Issuer may charge  the  Holder  for its  expenses  (including  the fees and
expenses of the Trustee) in replacing a Security.  Every replacement Security is
an additional  obligation of the Issuer.  The provisions of this Section 2.7 are
exclusive  and shall  preclude all other rights and remedies with respect to the
replacement or payment of mutilated, destroyed, lost or stolen Securities.

                  SECTION 2.8 Outstanding Securities. The Securities Outstanding
at any time are all of the Securities  authenticated by the Trustee,  except for
those canceled by it, those delivered to it for cancellation and those described
in this Section 2.8 as not Outstanding.

                                      -17-
<PAGE>

                  If a Security is replaced  pursuant to Section  2.7, it ceases
to be Outstanding  until a Responsible  Officer of the Trustee actually receives
proof  satisfactory  to it that the  replaced  Security  is held by a bona  fide
purchaser.

                  If the Paying  Agent (other than the Issuer or an Affiliate of
the Issuer) holds on a redemption date or maturity date money  sufficient to pay
the principal of and accrued  interest on Securities  payable on that date, then
on and after that date such  Securities  cease to be Outstanding and interest on
them ceases to accrue.

                  Subject  to  Section  6.4,  a  Security  does not  cease to be
Outstanding because the Issuer or an Affiliate of the Issuer holds the Security.

                  SECTION 2.9 Temporary Securities. Until defini tive Securities
are ready for  delivery,  the  Issuer  may  prepare  and,  upon the order of the
Issuer,  the  Trustee  shall  authenticate   temporary   Securities.   Temporary
Securities shall be  substantially in the form of definitive  Securities but may
have variations that the Issuer considers appropri ate for temporary Securities.
Without  unreasonable  delay,  the Issuer  shall  prepare and the Trustee  shall
authenticate  definitive Securities in exchange for temporary Securities.  Until
such  exchange,  temporary  Securities  shall be  entitled  to the same  rights,
benefits and privileges as definitive Securities.

                  SECTION 2.10 Cancellation.  The Issuer at any time may deliver
Securities  to the Trustee for  cancellation.  The  Registrar,  Paying Agent and
Conversion Agent shall forward to the Trustee any Securities surrendered to them
for transfer, exchange, payment or conversion. The Trustee and no one else shall
cancel all Securities surrendered for transfer, exchange, payment, conversion or
cancellation.  The Issuer may not issue new Securities to replace  Securities it
has paid or  delivered  to the  Trustee  for  cancellation  or which  have  been
converted.  All  canceled  Securities  shall be held by the Trustee and shall be
disposed of in accordance with its customary  procedures (and

                                      -18-
<PAGE>

certification of their cancellation shall be delivered to the Issuer).

                  SECTION 2.11 Defaulted  Interest.  If the Issuer defaults in a
payment of interest on the  Securities,  it shall pay the defaulted  interest in
any lawful manner plus, to the extent lawful,  interest payable on the defaulted
interest,  to the persons who are Holders on a subsequent  special  record date,
which date shall be at least five  Business  Days prior to the payment  date, in
each case at the rate provided in the  Securities and in Section 3.1. The Issuer
shall fix or cause to be fixed each such special  record date and payment  date.
At least 15 days before a special record date, the Issuer (or the Trustee in the
name of and at the expense of the Issuer)  shall forward to the Holders a notice
prepared by the Issuer that states the special record date, the related  payment
date and the amount of such interest to be paid.

                  SECTION  2.12  CUSIP  Numbers.   The  Issuer  in  issuing  the
Securities may use "CUSIP"  numbers (if then generally in use),  and, if so, the
Trustee shall use "CUSIP"  numbers in notices of redemption as a convenience  to
Holders;  provided that any such notice may state that no representation is made
as to the  correctness of such numbers either as printed on the Securities or as
contained in any notice of  redemption  and that  reliance may be placed only on
the  other  identification  numbers  printed  on the  Securities,  and any  such
redemption  shall not be affected by any defect in or omission of such  numbers.
The  Company  will  promptly  notify the  Trustee  of any change in the  "CUSIP"
numbers.

                  SECTION 2.13 Global Securities.

                  (a) Each Global  Security  authenticated  under this Indenture
shall be registered in the name of the  Depositary  designated by the Issuer for
such Global  Security or a nominee thereof and delivered to such Depositary or a
nominee  thereof or  custodian  therefor,  and each such Global  Security  shall
constitute a single Security for all purposes of this Indenture.

                                      -19-
<PAGE>

                  (b) Notwithstanding any other provision in this Indenture,  no
Global Security may be exchanged in whole or in part for Securities  registered,
and no transfer of a Global  Security in whole or in part may be registered,  in
the name of any Person other than the Depositary  for such Global  Security or a
nominee  thereof unless (i) such  Depositary (A) has notified the Issuer and the
Trustee in writing that it is unwilling or unable to continue as Depositary  for
such Global  Security or (B) has ceased to be a clearing  agency  registered  as
such under the  Exchange Act or  announces  an  intention  permanently  to cease
business or does in fact do so, (ii) there shall have occurred and be continuing
an Event of Default  with respect to such Global  Security,  or (iii) the Issuer
delivers an  Officers'  Certificate  to the Trustee  stating that the Issuer has
determined not to have all the Securities represented by the Global Security.

                  (c)  If any  Global  Security  is to be  exchanged  for  other
Securities or cancelled in whole, it shall be surrendered by or on behalf of the
Depositary  or its  nominee  to the  Trustee,  as  Registrar,  for  exchange  or
cancellation,  as  provided  in this  Article.  If any Global  Security is to be
exchanged for other  Securities or cancelled in part, or if another  Security is
to be  exchanged  in whole or in part for a  beneficial  interest  in any Global
Security,  in each case as provided in this Article, then either (i) such Global
Security shall be so surrendered  for exchange or  cancellation,  as provided in
this Article, or (ii) the principal amount thereof shall be reduced or increased
by an amount equal to the portion  thereof to be so exchanged or  cancelled,  or
equal to the  principal  amount of such other  Security to be so exchanged for a
beneficial  interest  therein,  as the case may be,  by means of an  appropriate
adjustment  made on the records of the  Trustee,  as  Registrar,  whereupon  the
Trustee shall instruct the Depositary or its authorized representative to make a
corresponding  adjustment  to its  records  in  accordance  with its  rules  and
procedures.  Upon any such  surrender or  adjustment of a Global  Security,  the
Trustee shall as provided in this Article,  authenticate  and make available for
delivery any  Securities  issuable in exchange for such Global  Security (or any
portion thereof)

                                      -20-
<PAGE>

to or upon the order of,  and  registered  in such names as may be  directed  in
writing by, the Depositary or its authorized representative. Upon the request of
the Trustee in connection with the occurrence of any of the events  specified in
the preceding paragraph, the Issuer shall promptly make available to the Trustee
a reasonable supply of Securities that are not in the form of Global Securities.
The Trustee  shall be entitled to rely upon any order,  direction  or request of
the Depositary or its authorized  representative which is given or made pursuant
to this  Article  if such  order,  direction  or  request  is  given  or made in
accordance with the Depositary's rules and procedures.

                  (d)  Every   Security   authenticated   and   delivered   upon
registration of transfer of, or in exchange for or in lieu of, a Global Security
or any portion thereof, whether pursuant to this Article or otherwise,  shall be
authenticated  and  delivered in the form of, and shall be, a registered  Global
Security,  unless such Security is registered in the name of a Person other than
the Depositary for such Global Security or a nominee thereof, in which case such
Registered  Security shall be authenticated  and delivered in definitive,  fully
registered form, without interest coupons.

                  (e) The  Depositary or its nominee,  as registered  owner of a
Global  Security,  shall be the Holder of such Global  Security for all purposes
under the Indenture and the Securities,  and owners of beneficial interests in a
Global Security shall hold such interests pursuant to the Depositary's rules and
procedures.  Accordingly,  any  such  owner's  beneficial  interest  in a Global
Security  will be shown  only on, and the  transfer  of such  interest  shall be
effected only through,  records  maintained by the  Depositary or its nominee or
its  participants  and such owners of beneficial  interests in a Global Security
will not be  considered  the owners or  holders  thereof.  Notices  given to the
Holders of the  Security  shall be deemed given if sent to the  Depositary.  The
Trustee shall have no obligation to the beneficial owners of the Securities.


                                      -21-
<PAGE>


                  (f) Upon the transfer of beneficial  interests in a Restricted
Global  Security  under  circumstances  permitting the removal of the Restricted
Securities legend contemplated in Section 2.14 if the Securities  represented by
such  beneficial  interest  were  not in the  form of a  Global  Security,  such
transferred beneficial interest shall be represented by a beneficial interest in
a Global Security that is not a Restricted Global Security.

                  SECTION 2.14 Transfer  Restrictions.  (a) Securities  shall be
stamped or  otherwise  be  imprinted  with the legends  containing  the transfer
restrictions  set forth on the face of the text of the  Securities  attached  as
Exhibit  A  hereto.  The  legends  so  provided  on the  face of the text of the
Securities that relate to Restricted Securities and Restricted Global Securities
may be removed  from such  Security,  upon  receipt by the  Trustee of an Issuer
Order, (i) two years from the later of issuance of the Security or the date such
Security (or any  predecessor)  was last  acquired  from an  "affiliate"  of the
Issuer  within  the  meaning  of Rule 144  under  the  Securities  Act,  (ii) in
connection with a sale made pursuant to the volume (and other  restrictions)  of
Rule 144 under the Securities Act following one year from such time, or (iii) in
connection with any sale in a transaction  registered  under the Securities Act,
provided that, if the legend is removed and the Security is subsequently held by
such an affiliate of the Issuer, the legend shall be reinstated.

         (b) Each Holder of a Security  agrees to  indemnify  the Issuer and the
Trustee  against any liability  that may result from the  transfer,  exchange or
assignment  of such  Holder's  security in  violation  of any  provision of this
Indenture and/or applicable United States Federal or state securities law.

         (c) The Trustee shall have no obligation or duty to monitor,  determine
or inquire as to compliance with any restrictions on transfer imposed under this
Indenture or under  applicable  law with respect to any transfer of any interest
in  any  Security   (including  any  transfers   between  or  among   Depositary
participants or beneficial owners of



                                      -22-
<PAGE>

interest  in any  Global  Security)  other  than  to  require  delivery  of such
certificates and other  documentation or evidence as are expressly  required by,
and to do so if and when expressly required by the terms of, this Indenture, and
to examine  the same to  determine  substantial  compliance  as to form with the
express requirements hereof.


                                  ARTICLE THREE

                                    COVENANTS

                  SECTION  3.1 Payment of  Principal  and  Interest.  The Issuer
covenants  and agrees that it will duly and  punctually  pay or cause to be paid
the  principal  of, and  interest  on,  each of the  Securities  at the place or
places, at the respective times and in the manner provided in the Securities and
this Indenture.  Interest on the Securities  shall be computed on the basis of a
360-day  year of twelve  30-day  months.  Each  instalment  of  interest  on the
Securities  may be paid by mailing  checks for such interest  payable to or upon
the written  order of the Holders of Securities  entitled  thereto as they shall
appear on the registry books of the Issuer.

                  SECTION 3.2  Written  Statement  to  Trustee.  The Issuer will
deliver to the Trustee, within 120 days after the end of each fiscal year of the
Issuer ending after the date hereof, an Officers'  Certificate,  stating that in
the course of the  performance by the signers of their duties as officers of the
Issuer they would  normally have knowledge of any default or  non-compliance  by
the Issuer in the perfor  mance or  fulfillment  of any  covenant,  agreement or
condition  contained  in  this  Indenture,  stating  whether  or not  they  have
knowledge of any such default or non-compliance (without regard to any period of
grace or requirement of notice provided hereunder),  and, if so, specifying each
such  default or  non-compliance  of which the signers  have  knowledge  and the
nature thereof.

         The Issuer shall deliver to the Trustee, as soon as possible and in any
event within five days after the Issuer

                                      -23-
<PAGE>

becomes aware of the occurrence of any Event of Default or an event which,  with
notice or the lapse of time or both,  would  constitute an Event of Default,  an
Officers'  Certificate  setting  forth the  details  of such Event of Default or
default and the action which the Issuer proposes to take with respect thereto.

                  SECTION 3.3 Corporate Existence. Subject to Article Eight, the
Issuer will do or cause to be done all things  necessary to preserve and keep in
full force and effect its corporate existence,  rights and franchises;  provided
that the Issuer shall not be required to preserve its corporate existence or any
such right or  franchise  if the Issuer shall  determine  that the  preservation
thereof is no longer  desirable in the conduct of its business and that the loss
thereof is not  disadvantageous  in any  material  respect to the Holders of the
Securities.

                  SECTION  3.4 Reports by the Issuer.  The Issuer  covenants  to
file with the  Trustee,  within 15 days after the Issuer is required to file the
same  with  the  SEC,  copies  of the  annual  reports  and of the  information,
documents, and other reports (or copies of such portions of any of the foregoing
as the SEC may from time to time by rules and regulations  prescribe)  which the
Issuer may be  required  to file with the SEC  pursuant to Section 13 or Section
15(d) of the Exchange Act, or if the Issuer is not required to file information,
documents, or reports pursuant to either of such sections, then to file with the
Trustee,  in accordance with rules and regulations  prescribed from time to time
by the SEC, such of the supplementary and periodic information,  documents,  and
reports which may be required pursuant to Section 13 of the Exchange Act; or, in
respect of a security listed and registered on a national securities exchange or
on NASDAQ as may be prescribed from time to time in such rules and  regulations.
At any  time  when the  Issuer  is not  subject  to  Section  13 or 15(d) of the
Exchange Act, upon request of Holders and  prospective  purchasers of Securities
or the Class A Common Stock issuable upon  conversion  thereof,  the Issuer will
promptly  furnish  or cause to be  furnished  to such  holders  and  prospective
purchasers,  copies of the information  required to be delivered to such holders

                                      -24-
<PAGE>

and prospective  purchasers of such securities pursuant to Rule 144A(d)(4) under
the  Securities  Act (or any  successor  provision  thereto)  in order to permit
compliance  with Rule 144A in  connection  with  resales by such holders of such
securities.  The Issuer will pay the  expenses of printing and  distributing  to
such holders and prospective purchasers all such documents.

                  Delivery of such  reports,  information  and  documents to the
Trustee is for  informational  purposes only and the  Trustee's  receipt of such
shall not constitute constructive notice of any information contained therein or
determinable  from  information   contained  therein,   including  the  Issuer's
compliance  with any of its  covenants  hereunder  (as to which the  Trustee  is
entitled to rely exclusively on Officers' Certificates).

                  SECTION 3.5 Waiver of Usury Defense.  The Issuer covenants (to
the extent that it may  lawfully  do so) that it shall not  assert,  plead (as a
defense or  otherwise)  or in any manner  whatsoever  claim (and shall  actively
resist any attempt to compel it to assert,  plead or claim) in any action,  suit
or  proceeding  that the interest  rate on the  Securities  violates  present or
future usury or other laws relating to the interest  payable on any indebtedness
and shall not otherwise  avail itself (and shall actively  resist any attempt to
compel it to avail itself) of the benefits or advantages of any such laws.

                  SECTION 3.6 Payment of Excess  Cash  Dividends.  If the Issuer
shall  declare  and pay  cash  dividends  on its  Class  A  Common  Stock  in an
annualized  per share amount which exceeds the greater of (i) the annualized per
share amount of the  immediately  preceding  cash dividend on its Class A Common
Stock (as adjusted to reflect any of the events listed in Sections 12.4 or 12.5)
and (ii)  15% of the  Last  Sale  Price  of the  Class A Common  Stock as of the
Trading Day immediately  preceding the date of declaration of such dividend (the
per share amount of any such per share  excess,  to the extent of such per share
excess,  being  herein  called an "Excess  Amount"),  then in any such event the
Holders shall have the right to receive, and the Issuer will pay to

                                      -25-
<PAGE>

each  such  Holder,  at the time of the  payment  of such  Class A Common  Stock
dividend, an amount equal to such Excess Amount (calculated by the Issuer on the
basis of the  number of  shares of Class A Common  Stock  that  would  have been
issued to a Holder upon  conversion of the Securities held by such Holder on the
record date for the payment of such  dividend)  unless the Holder  converts  and
receives  such  dividend as a holder of Class A Common  Stock.  The Issuer shall
give the Trustee written notice of the payment of Excess Amounts to the Holders.

                  SECTION 3.7  Registration  Rights.  The Issuer agrees that the
Holders  from  time  to  time  of  Registrable  Securities  (as  defined  in the
Registration  Rights Agreement) are entitled to the benefits of the Registration
Rights Agreement. Whenever in this Indenture there is mentioned, in any context,
the payment of interest on, or in respect of, any  Security,  such mention shall
be deemed to include mention of the payment of liquidated  damages on Securities
constituting  Registrable  Securities  as  contemplated  in  Section  3  of  the
Registration  Rights  Agreement  to the  extent  that,  in  such  context,  such
liquidated  damages are, were or would be payable in respect thereof pursuant to
the provisions of the Registration Rights Agreement.


                                  ARTICLE FOUR

                           REMEDIES OF THE TRUSTEE AND
                       SECURITYHOLDERS ON EVENT OF DEFAULT

                  SECTION  4.1  Event  of  Default  Defined;  Accelera  tion  of
Maturity; Waiver of Default. "Event of Default" with respect to Securities where
used herein,  means each one of the  following  events which shall have occurred
and be continuing  (whatever the reason for such Event of Default and whether it
shall be voluntary or involuntary or be effected by operation of law or pursuant
to any judgment,  decree or order of any court or any order,  rule or regulation
of any administrative or governmental body):

                                      -26-
<PAGE>

                  (a) default in the payment of any  instalment of interest upon
         any of the  Securities  as and  when  the  same  shall  become  due and
         payable, and continuance of such default for a period of 30 days; or

                  (b) default in the payment of all or any part of the principal
         of or premium,  if any, upon any of the Securities as and when the same
         shall become due and payable either at maturity, upon any redemption or
         acceleration, by declaration or otherwise; or

                  (c)  failure  on the part of the  Issuer to observe or perform
         any other of the  covenants or  agreements on the part of the Issuer in
         the Securities or in this  Indenture  contained for a period of 60 days
         after the date on which written notice specifying such failure, stating
         that such notice is a "Notice of Default"  hereunder and demanding that
         the Issuer  remedy the same,  shall  have been given by  registered  or
         certified mail, return receipt requested, to the Issuer by the Trustee,
         or to the  Issuer  and the  Trustee  by the  Holders of at least 25% in
         aggregate principal amount of the Outstanding Securities; or

                  (d) a court having  jurisdiction in the premises shall enter a
         decree or order for relief in  respect of the Issuer in an  involuntary
         case or proceeding  under any applicable  Federal or State  bankruptcy,
         insolvency,  reorganization  or other  similar law now or  hereafter in
         effect,  or a decree  or order  adjudging  the  Issuer  a  bankrupt  or
         insolvent,   approving   as   properly   filed   a   petition   seeking
         reorganization, assignment, adjustment or composition of, or in respect
         of, the Issuer under any applicable  Federal or State law or appointing
         a receiver, liquidator,  assignee, custodian, trustee, sequestrator (or
         similar  official)  of the  Issuer or for any  substantial  part of its
         property or ordering the winding up or liquidation of its affairs,  and
         such decree or order shall  remain  unstayed and in effect for a period
         of 60 consecutive days; or

                                      -27-
<PAGE>

                  (e) the Issuer shall  commence a voluntary  case or proceeding
         under  any  applicable   Federal  or  State   bankruptcy,   insolvency,
         reorganization  or other similar law now or hereafter in effect, or any
         other case or proceeding to be adjudicated a bankrupt or insolvent,  or
         consent to the entry of an order for relief in an  involuntary  case or
         proceeding   under  any   applicable   Federal  or  State   bankruptcy,
         insolvency,  reorganization or other similar law or to the commencement
         of any  bankruptcy or insolvency  case or proceeding  against it, or to
         the  filing  by  it  of  a  petition  or  answer  or  consent   seeking
         reorganization or relief under any applicable  Federal or State law, or
         consent to the filing of such petition or to the  appointment or taking
         possession by a receiver, liquidator,  assignee, cus todian, trustee or
         sequestrator (or similar official) of the Issuer or for any substantial
         part of its prop erty, or make any general  assignment  for the benefit
         of creditors, or the admission by it in writing of its inability to pay
         its debts  generally  as they become  due,  or the taking of  corporate
         action by the Issuer in furtherance of any such action.

                  If an Event of Default  occurs and is continuing  with respect
to the Securities,  then, and in each and every such case,  unless the principal
of all the  Securities  shall have already  become due and  payable,  either the
Trustee or the Holders of not less than 25% in aggregate principal amount of the
Securities then Outstanding  hereunder,  by notice in writing to the Issuer (and
to the Trustee if given by Securityholders), may declare the entire principal of
all the  Securities,  and the interest  accrued  thereon,  to be due and payable
immediately, and upon any such declaration the same shall become immediately due
and payable.  This provision,  however,  is subject to the condition that if, at
any time after the Securities  shall have been so declared due and payable,  and
before any  judgment or decree for the payment of the moneys due shall have been
obtained  or  entered as  hereinafter  provided,  the Issuer  shall pay or shall
deposit with the Trustee a sum  sufficient  to pay all matured  installments  of
interest upon all the  Securities  and the  principal of any and all  Securities
which shall have

                                      -28-
<PAGE>

become due otherwise  than by  acceleration  (with  interest upon such principal
and, to the extent that payment of such interest is enforceable under applicable
law,  on  overdue  installments  of  interest,  at the same  rate as the rate of
interest  specified in the  Securities,  to the date of such payment or deposit)
and such amount as shall be sufficient to cover  reasonable  compensation to the
Trustee and each predecessor  Trustee,  their respective  agents,  attorneys and
counsel, and all other expenses and liabilities incurred, and all advances made,
by the Trustee and each predecessor  Trustee except as a result of negligence or
bad faith, and if any and all Events of Default under the Indenture,  other than
the non-payment of the interest on and principal of Securities  which shall have
become due by acceleration,  shall have been cured, waived or otherwise remedied
as provided  herein--then and in every such case of such a cure the Holders of a
majority in aggregate  principal amount of the Securities then  Outstanding,  by
written  notice to the Issuer and to the  Trustee,  may waive all  defaults  and
rescind and annul such declaration and its  consequences,  but no such waiver or
rescission and annulment shall extend to or shall affect any subsequent  default
or shall impair any right consequent thereon.

                  SECTION 4.2 Collection of Indebtedness by Trustee; Trustee May
Prove Debt.  The Issuer  covenants that (a) in case default shall be made in the
payment  of any  instalment  of  interest  on any of the  Securities  when  such
interest  shall  have  become  due and  payable,  and such  default  shall  have
continued  for a period of 30 days or (b) in case  default  shall be made in the
payment of all or any part of the principal of or premium, if any, on any of the
Securities  when the same  shall  have  become  due and  payable,  whether  upon
maturity or upon any redemption or by declaration or otherwise, then upon demand
of the  Trustee,  the  Issuer  will pay to the  Trustee  for the  benefit of the
Holders of the  Securities  the whole amount that then shall have become due and
payable on all such Securities for principal,  premium, if any, or interest,  as
the case may be (with  interest  to the date of such  payment  upon the  overdue
principal and, to the extent that payment of such interest is enforceable  under
applicable law, on overdue installments

                                      -29-
<PAGE>

of  interest  at the  same  rate  as  the  rate  of  interest  specified  in the
Securities;  and in addition thereto, such further amount as shall be sufficient
to cover the costs and expenses of collection, including reasonable compensation
to the Trustee and each predecessor Trustee, their respective agents,  attorneys
and counsel,  and any expense and liabili ties incurred,  and all advances made,
by the Trustee and each predecessor Trustee except as a result of its negligence
or bad faith.

                  Until such demand is made by the  Trustee,  the Issuer may pay
the  principal of and premium,  if any,  and interest on the  Securities  to the
registered Holders, whether or not the Securities be overdue.

                  In case the Issuer  shall fail  forthwith  to pay such amounts
upon such  demand,  the  Trustee,  in its own name and as  trustee of an express
trust, shall be entitled and empowered to institute any action or proceedings at
law or in  equity  for the  collection  of the sums so due and  unpaid,  and may
prosecute any such action or  proceedings  to judgment or final decree,  and may
enforce any such  judgment or final decree  against the Issuer or other  obligor
upon the  Securi  ties and  collect  in the  manner  provided  by law out of the
property of the Issuer or other obligor upon the Securities,  wherever situated,
the moneys adjudged or decreed to be payable.

                  In case there  shall be pending  proceedings  relative  to the
Issuer or any other  obligor  upon the  Securities  under Title 11 of the United
States Code or any other  applicable  Federal or state  bankruptcy,  insolvency,
reorganization or other similar law, or in case a receiver,  assignee or trustee
in bankruptcy or  reorganization,  liquidator,  sequestrator or similar official
shall have been appointed for or taken  possession of the Issuer or its property
or such other obligor, or in case of any other comparable  judicial  proceedings
relative to the Issuer or other obligor upon the Securities, or to the creditors
or property of the Issuer or such other obligor,  the Trustee,  irrespective  of
whether the principal of the Securities shall then be due and payable as therein
expressed or by

                                      -30-
<PAGE>

declaration or otherwise and irrespective of whether the Trustee shall have made
any demand  pursuant to the  provisions of this  Section,  shall be entitled and
empowered, by intervention in such proceedings or otherwise:

                  (a) to file and prove a claim or claims  for the whole  amount
         of principal, premium, if any, and interest owing and unpaid in respect
         of the Securities, and to file such other papers or documents as may be
         necessary  or  advisable  in order to have the  claims of the  Trustees
         (including  any claim for  reasonable  compensation  to the Trustee and
         each predecessor  Trustee,  and their respective agents,  attorneys and
         counsel,   and  for  reimbursement  of  all  expenses  and  liabilities
         incurred,  and all advances  made, by the Trustee and each  predecessor
         Trustee,  except as a result of  negligence  or bad  faith)  and of the
         Securityholders  allowed in any  judicial  proceedings  relative to the
         Issuer or other  obligor upon the  Securities,  or to the  creditors or
         property of the Issuer or such other obligor,

                  (b) unless  prohibited by applicable law and  regulations,  to
         vote on behalf of the Holders of the  Securities  in any  election of a
         trustee   or  a  standby   trustee  in   arrangement,   reorganization,
         liquidation  or other  bankruptcy or insolvency  proceedings  or person
         performing similar functions in comparable proceedings, and

                  (c) to  collect  and  receive  any  moneys  or other  property
         payable  or  deliverable  on any such  claims,  and to  distribute  all
         amounts received with respect to the claims of the  Securityholders and
         of  the  Trustee  on  their  behalf;  and  any  trustee,  receiver,  or
         liquidator, custodian or other similar official is hereby authorized by
         each of the  Securityholders  to make payments to the Trustee,  and, in
         the event that the  Trustee  shall  consent  to the making of  payments
         directly to the Securityholders,  to pay to the Trustee such amounts as
         shall be sufficient to cover  reasonable  compensation  to the Trustee,
         each  predecessor  Trustee

                                      -31-
<PAGE>

         and their  respective  agents,  attorneys  and  counsel,  and all other
         expenses  and  liabilities  incurred,  and all  advances  made,  by the
         Trustee and each  predecessor  Trustee except as a result of negligence
         or bad faith.

                  Nothing  herein  contained  shall be deemed to  authorize  the
Trustee to  authorize  or consent to or vote for or accept or adopt on behalf of
any  Securityholder  any  plan of  reorganization,  arrangement,  adjustment  or
caption  affecting  the  Securities or the rights of any Holder  thereof,  or to
authorize the Trustee to vote in respect of the claim of any  Securityholder  in
any such proceeding except, as aforesaid,  to vote for the election of a trustee
in bankruptcy or similar person.

                  All  rights of  action  and of  asserting  claims  under  this
Indenture, or under any of the Securities, may be prosecuted and enforced by the
Trustee  without  the  possession  of any of the  Securities  or the  production
thereof on any trial or other proceedings  relative thereto, and any such action
or  proceedings  instituted  by the Trustee  shall be brought in its own name as
trustee  of an express  trust,  and any  recovery  of  judgment,  subject to the
payment of the expenses,  disbursements  and  compensation of the Trustee,  each
predecessor Trustee and their respective agents and attorneys,  shall be for the
ratable benefit of the Holders of the Securities.

                  In any  proceedings  brought  by the  Trustee  (and  also  any
proceedings  involving the  interpretation of any provision of this Indenture to
which the Trustee  shall be a party) the Trustee  shall be held to represent all
the Holders of the Securities in respect of which such action was taken,  and it
shall not be necessary to make any Holders of the Securities parties to any such
proceedings.

                  SECTION 4.3 Application of Proceeds.  Any moneys  collected by
the Trustee  pursuant to this Article in respect of Securities  shall be applied
in the following order at the date or dates fixed by the Trustee and, in case of
the  distribution  of such  moneys on account of  principal  or  interest,  upon
presentation  of the several  Securities  and

                                      -32-
<PAGE>

         stamping  (or  otherwise  noting)  thereon  the  payment,   or  issuing
         Securities in reduced  principal  amounts in exchange for the presented
         Securities if only partially  paid, or upon surrender  thereof if fully
         paid:


                           FIRST:   To  the  payment  of  costs  and   expenses,
                  including  any and all amounts due the Trustee  under  Section
                  5.5;

                           SECOND: In case the principal of the Securities shall
                  not have become and be then due and payable, to the payment of
                  interest  on the  Securities  in  default  in the order of the
                  maturity of the  installments of such interest,  with interest
                  (to the extent that such  interest  has been  collected by the
                  Trustee) upon the overdue installments of interest at the same
                  rate as the rate of interest specified in the Securities, such
                  payments to be made  ratably to the person  entitled  thereto,
                  without discrimination or preference;

                           THIRD: In case the principal of the Securities  shall
                  have become and shall be then due and payable,  to the payment
                  of the  whole  amount  then  owing  and  unpaid  upon  all the
                  Securities for principal,  premium, if any, and interest, with
                  interest upon the overdue  principal and premium,  if any, and
                  (to the extent that such  interest  has been  collected by the
                  Trustee)  upon  overdue  installments  of interest at the same
                  rate as the rate of interest specified in the Securities;  and
                  in case such moneys shall be  insufficient  to pay in full the
                  whole  amount so due and unpaid upon the  Securities,  then to
                  the payment of such principal,  premium, if any, and interest,
                  without  preference or priority of principal (and premium,  if
                  any)  over  interest,  or  of  interest  over  principal  (and
                  premium,  if any),  or of any  instalment of interest over any
                  other  instalment  of interest,  or of any  Security  over any
                  other  Security,  ratably to the aggregate of such  principal,
                  premium, if any, and accrued and unpaid interest; and

                                      -33-
<PAGE>

                           FOURTH:  To the payment of the remainder,  if any, to
                  the Issuer or any other person lawfully entitled thereto.

                  SECTION 4.4 Suits for Enforcement. In case an Event of Default
has  occurred,  has not been  waived and is  continuing,  the Trustee may in its
discretion  proceed  to protect  and  enforce  the  rights  vested in it by this
Indenture by such  appropriate  judicial  proceedings  as the Trustee shall deem
most  effectual to protect and enforce any of such  rights,  either at law or in
equity or in bankruptcy or otherwise,  whether for the specific  enforcement  of
any covenant or agreement  contained in this Indenture or in aid of the exercise
of any  power  granted  in this  Indenture  or to  enforce  any  other  legal or
equitable right vested in the Trustee by this Indenture or by law.

                  SECTION  4.5   Restoration   of  Rights  or   Abandonment   of
Proceedings.  In case the Trustee or any Securityholder  shall have proceeded to
enforce  any right under this  Indenture  and such  proceedings  shall have been
discontinued  or  abandoned  for any  reason,  or  shall  have  been  determined
adversely to the Trustee or to such Securityholder, then and in every such case,
subject to any determination in such proceeding, the Issuer, the Trustee and the
Securityholders  shall be restored  severally and  respectively  to their former
positions and rights hereunder,  and thereafter all rights,  remedies and powers
of the Issuer, the Trustee and the  Securityholders  shall continue as though no
such proceedings had been taken.

                  SECTION  4.6  Limitations  on Suits by  Security  holders.  No
Holder of any  Security  shall  have any right by virtue or by  availing  of any
provision of this Indenture to institute any action or  proceeding,  judicial or
otherwise,  at law or in equity or in bankruptcy  or otherwise  upon or under or
with respect to this Indenture, or for the appoint ment of a trustee,  receiver,
liquidator,  custodian  or  other  similar  official  or for  any  other  remedy
hereunder, unless such Holder previously shall have given to the Trustee written
notice of a continuing  Event of Default as herein before  provided,  and unless
also the  Holders  of not less

                                      -34-
<PAGE>

than 25% in aggregate  principal amount of the Securities then Outstanding shall
have made written request upon a Responsible Officer of the Trustee to institute
such action or proceedings  in its own name as trustee  hereunder and shall have
offered to the Trustee  indemnity  satisfactory  to it as it may require against
the costs,  expenses and  liabilities to be incurred  therein or thereby and the
Trustee  for 45 days after its  receipt  of such  notice,  request  and offer of
indemnity  shall have failed to institute any such action or proceedings  and no
direction  inconsistent  with such  written  request  shall have been given to a
Responsible  Officer of the Trustee pursuant to Section 4.9; it being understood
and intended,  and being  expressly  covenanted by the Holder of every  Security
with every other Holder of the Securities  and the Trustee,  that no one or more
Holders of Securities  shall have any right in any manner  whatever by virtue or
by availing of any provision of this  Indenture to affect,  disturb or prejudice
the  rights of any other  Holder of  Securities,  or to obtain or seek to obtain
priority  over or  preference  to any other such  Holder or to enforce any right
under this  Indenture,  except in the manner herein  provided and for the equal,
ratable and common benefit of all Holders of Securities.  For the protection and
enforcement of the provisions of this Section, each and every Securityholder and
the Trustee shall be entitled to such relief as can be given either at law or in
equity.

                  SECTION 4.7 Unconditional Right of Security holders to Receive
Principal,  Premium and  Interest,  to Convert and to Institute  Certain  Suits.
Notwithstanding  any other  provision in this Indenture and any provision of any
Security,  the right of any Holder of any  Security  to  receive  payment of the
principal of and premium, if any, and inter est on such Security on or after the
respective due dates  expressed in such Security (or, in the case of redemption,
on the  applicable  Redemption  Date or  Repurchase  Date),  or to convert  such
Security  in  accordance  with  Article  Twelve,  or to  institute  suit for the
enforcement of any such payment on or after such  respective  dates,  or for the
enforcement of such conversion right,  shall not be impaired or affected

                                      -35-
<PAGE>

without the written consent of such Holder, with a copy thereof to the Trustee.

                  SECTION 4.8 Powers and Remedies Cumulative;  Delay or Omission
Not Waiver of Default.  Except as  provided in Sections  2.7, no right or remedy
herein  conferred upon or reserved to the Trustee or to the  Securityholders  is
intended  to be  exclusive  of any other  right or remedy,  and every  right and
remedy shall,  to the extent  permitted by law, be cumulative and in addition to
every other right and remedy given hereunder or now or hereafter existing at law
or in equity or  otherwise.  The  assertion or employment of any right or remedy
hereunder,  or  otherwise,   shall  not  prevent  the  concurrent  assertion  or
employment of any other appropriate right or remedy.

                  No delay or omission of the Trustee or of any Holder of any of
the Securities to exercise any right or power accruing upon any Event of Default
occurring and  continuing  as aforesaid  shall impair any such right or power or
shall  be  construed  to  be a  waiver  of  any  such  Event  of  Default  or an
acquiescence  therein; and, subject to Section 4.6, every power and remedy given
by this  Indenture  or by law to the  Trustee or to the  Securityholders  may be
exercised from time to time, and as often as shall be deemed  expedient,  by the
Trustee or by the Securityholders, as the case may be.

                  SECTION  4.9  Control  by  Securityholders.  The  Holders of a
majority in aggregate principal amount of the Securities at the time Outstanding
shall  have the right to  direct  in  writing  the  time,  method,  and place of
conducting any proceeding for any remedy available to the Trustee, or exercising
any  trust or  power  conferred  on the  Trustee;  provided  that  such  written
direction  shall not be otherwise than in accordance with law and the provisions
of this  Indenture;  and provided  further that  (subject to the  provisions  of
Section  5.1) the  Trustee  shall  have the right to  decline to follow any such
direction if the Trustee,  being advised by counsel,  shall  determine  that the
action or proceeding so directed may expose the Trustee to personal liability or
if the  Trustee  in good  faith  by its  board  of

                                      -36-
<PAGE>

directors or the executive committee thereof shall so determine that the actions
or  forbearances  specified  in or  pursuant to such  direction  would be unduly
prejudicial  to the  interests of Holders of the  Securities  not joining in the
giving of said direction,  it being understood that (subject to Section 5.1) the
Trustee  shall  have  no  duty to  ascertain  whether  or not  such  actions  or
forbearances are unduly prejudicial to such Holders.

                  Nothing  in this  Indenture  shall  impair  the  right  of the
Trustee in its  discretion  to take any action  deemed proper by the Trustee and
which is not inconsistent with such direction by Securityholders.

                  SECTION 4.10 Waiver of Past Defaults. Prior to the declaration
of the maturity of the  Securities  as provided in Section 4.1, the Holders of a
majority in aggregate principal amount of the Securities at the time Outstanding
may on behalf of the  Holders of all the  Securities  waive any past  default or
Event of Default hereunder and its consequences,  except a default in respect of
a covenant or provision  hereof which cannot be modified or amended  without the
consent of the Holder of each Security affected (including,  without limitation,
the provisions with respect to payment of principal of and premium,  if any, and
interest on such  Security or with respect to conversion  of such  Security).  A
copy of any such waiver or consent shall be delivered to the Trustee.

                  Upon any such waiver, such default shall cease to exist and be
deemed to have been  cured and not to have  occurred,  and any Event of  Default
arising  therefrom shall be deemed to have been cured,  and not to have occurred
for every  purpose of this  Indenture;  but no such waiver  shall  extend to any
subsequent or other  default or Event of Default or impair any right  consequent
thereon.

                  SECTION  4.11  Trustee  to Give  Notice  of  Default,  But May
Withhold in Certain  Circumstances.  The Trustee shall, at the Issuer's expense,
transmit  to the  Holders  of  Securities,  as the names and  addresses  of such
Holders appear on the registry books,  notice by mail of all defaults

                                      -37-
<PAGE>

known to a  Responsible  Officer of the Trustee,  such notice to be  transmitted
within 90 days after the  occurrence  thereof,  unless such defaults  shall have
been cured before the giving of such notice (the term  "default"  or  "defaults"
for the  purposes  of this  Section  being  hereby  defined to mean any event or
condition  which is, or with  notice or lapse of time or both would  become,  an
Event of Default);  provided that,  except in the case of default in the payment
of the  principal of or premium,  if any, or interest on any of the  Securities,
the Trustee shall be protected in withholding  such notice if and so long as the
board of directors,  the executive committee,  or a trust committee of directors
or trustees and/or Responsible  Officers of the Trustee in good faith determines
that the withholding of such notice is in the interests of the Securityholders.

                  SECTION 4.12 Right of Court to Require  Filing of  Undertaking
to Pay  Costs.  All  parties to this  Indenture  agree,  and each  Holder of any
Security by his  acceptance  thereof  shall be deemed to have  agreed,  that any
court may in its  discretion  require,  in any suit for the  enforcement  of any
right or remedy under this  Indenture or in any suit against the Trustee for any
action  taken,  suffered  or omitted by it as  Trustee,  the filing by any party
litigant in such suit other than the Trustee of an  undertaking to pay the costs
of such suit, and that such court may in its discretion assess reasonable costs,
including attorneys' fees, against any party litigant in such suit including the
Trustee,  having  due  regard  to the  merits  and good  faith of the  claims or
defenses made by such party  litigant;  but the provisions of this Section shall
not apply to any suit  instituted by the Trustee,  to any suit instituted by any
Securityholder  or group of  Securityholders  holding in the aggregate more than
10% in aggregate principal amount of the Securities at the time Outstanding,  or
to any suit instituted by any  Securityholder for the enforcement of the payment
of the  principal  of or  interest  on any  Security  on or  after  the due date
expressed  in such  Security  or for the  enforcement  of a right to convert any
Security in accordance with Article Twelve.

                                      -38-
<PAGE>

                  SECTION  4.13  Waiver of Stay or  Extension  Laws.  The Issuer
covenants  (to the extent  that it may  lawfully  do so) that it will not at any
time  insist  upon,  or plead,  or in any  manner  whatsoever  claim or take the
benefit or advantage of, any stay or extension law wherever  enacted,  now or at
any time hereafter in force,  which may affect the covenants or the  performance
of this  Indenture;  and the Issuer (to the extent  that it may  lawfully do so)
hereby  expressly  waives all benefit or advantage of any such law and covenants
that it will not  hinder,  delay or impede  the  execution  of any power  herein
granted to the Trustee,  but will suffer and permit the  execution of every such
power as though no such law had been enacted.


                                  ARTICLE FIVE

                             CONCERNING THE TRUSTEE

                  SECTION 5.1 Duties and Responsibilities of the Trustee; During
Default;  Prior to Default.  With  respect to the Holders of  Securities  issued
hereunder, the Trustee, prior to the occurrence of an Event of Default and after
the  curing or  waiving  of all  Events  of  Default  which  may have  occurred,
undertakes to perform such duties and only such duties as are  specifically  set
forth in this  Indenture.  In case an  Event  of  Default  with  respect  to the
Securities has occurred and is continuing  (which has not been cured or waived),
the Trustee  shall  exercise  such of the rights and powers vested in it by this
Indenture,  and use the same  degree of care and skill in their  exercise,  as a
prudent person would exercise or use under the  circumstances  in the conduct of
such person's own affairs.

                  No provision of this  Indenture  shall be construed to relieve
the Trustee from  liability  for its own  negligent  action,  its own  negligent
failure to act or its own wilful misconduct or bad faith, except that

                  (a) prior to the  occurrence  of an Event of Default and after
         the  curing or waiving  of all such  Events of  Default  which may have
         occurred:

                                      -39-
<PAGE>

                           (i) the duties and  obligations  of the Trustee  with
                  respect  to  Securities  shall  be  determined  solely  by the
                  express  provisions of this  Indenture,  and the Trustee shall
                  not be liable  except for the  performance  of such duties and
                  obligations as are  specifically  set forth in this Indenture,
                  and no implied  covenants  or  obligations  shall be read into
                  this Indenture against the Trustee; and

                           (ii) in the  absence  of bad faith on the part of the
                  Trustee, the Trustee may conclusively rely, as to the truth of
                  the statements and the correct ness of the opinions  expressed
                  therein,   upon   any   resolution,    statement,    officer's
                  certificate,  or any other certificate,  instrument or opinion
                  furnished to the Trustee and conforming to the requirements of
                  this  Indenture;  but in the  case  of  any  such  statements,
                  certificates  or opinions  which by any  provision  hereof are
                  specifically  required to be  furnished  to the  Trustee,  the
                  Trustee shall be under a duty to examine the same to determine
                  whether  or not  they  conform  to the  requirements  of  this
                  Indenture;

                  (b) the Trustee  shall not be liable for any error of judgment
         made in good faith by a Responsible Officer or Responsible  Officers of
         the Trustee,  unless it shall be proved that the Trustee was  negligent
         in ascertaining the pertinent facts; and

                  (c) the Trustee shall not be liable with respect to any action
         taken or omitted to be taken by it in good faith in accordance with the
         direction  of Holders  pursuant  to Section  4.9  relating to the time,
         method and place of conducting any proceeding for any remedy  available
         to the Trustee,  or exercising  any trust or power  conferred  upon the
         Trustee, under this Indenture.

                  None  of the  provisions  contained  in this  Indenture  shall
require the Trustee to expend or risk its own funds or otherwise  incur personal
financial  liability in the

                                      -40-
<PAGE>

performance  of any of its  duties or in the  exercise  of any of its  rights or
powers,  if there shall be reasonable ground for believing that the repayment of
such funds or  adequate  indemnity  against  such  liability  is not  reasonably
assured to it.

                  SECTION 5.2 Certain Rights of the Trustee.  Subject to Section
5.1:

                  (a) the Trustee may  conclusively  rely and shall be protected
         in acting or  refraining  from  acting upon any  resolution,  Officers'
         Certificate or any other certificate,  statement,  instrument, opinion,
         report, notice,  request,  direction,  consent, order, bond, debenture,
         note, coupon,  security or other paper or document believed by it to be
         genuine and to have been  signed or  presented  by the proper  party or
         parties;

                  (b) any  request,  direction,  order or demand  of the  Issuer
         mentioned  herein  shall  be  sufficiently  evidenced  by an  Officers'
         Certificate  (unless  other  evidence  in  respect  thereof  be  herein
         specifically prescribed);  and any resolution of the Board of Directors
         may be  evidenced  to the Trustee by a copy  thereof  certified  by the
         Secretary or an Assistant Secretary of the Issuer;

                  (c) the Trustee may consult with  counsel of its  selection at
         the expense of the Issuer and any advice or Opinion of Counsel shall be
         full and complete authorization and protection in respect of any action
         taken,  suffered or omitted to be taken by it  hereunder  in good faith
         and in accordance with such advice or Opinion of Counsel;

                  (d) the Trustee  shall be under no  obligation to exercise any
         of the trusts or powers vested in it by this  Indenture at the request,
         order  or  direction  of  any of the  Securityholders  pursuant  to the
         provisions of this Indenture,  unless such  Securityholders  shall have
         offered  to the  Trustee  security  or  indemnity  satisfactory  to the
         Trustee  against the costs,  expenses

                                      -41-
<PAGE>


         and liabilities which might be incurred therein or thereby;

                  (e) the  Trustee  shall not be liable  for any  action  taken,
         suffered  or  omitted  by it in good  faith  and  believed  by it to be
         authorized or within the discretion, rights or powers conferred upon it
         by this Indenture;

                  (f) prior to the  occurrence of an Event of Default  hereunder
         and after the curing or waiver of all Events of  Default,  the  Trustee
         shall not be bound to make any investigation  into the facts or matters
         stated in any resolution,  certificate, statement, instrument, opinion,
         report, notice,  request,  consent, order, approval,  appraisal,  bond,
         debenture,  note, coupon,  security,  or other paper or document unless
         requested  in  writing  so to do by  the  Holders  of not  less  than a
         majority  in  aggregate   principal   amount  of  the  Securities  then
         Outstanding,   but  a  Responsible  Officer  of  the  Trustee,  in  its
         discretion,  may make such further inquiries or investigation into such
         facts or matters as it may see fit, and, if the Trustee shall determine
         to make such inquiry or investigation,  it shall be entitled to examine
         the books,  records and premises of the Issuer,  personally or by agent
         or attorney;  provided that, if the payment within a reasonable time to
         the Trustee of the costs, expenses or liabilities likely to be incurred
         by it in the  making of such  investigation  is, in the  opinion of the
         Trustee, not reasonably assured to the Trustee by the security afforded
         to it by the terms of this Indenture, the Trustee may require indemnity
         satisfactory  to the Trustee  against such expenses or liabilities as a
         condition to proceeding;  the expenses of every such examination  shall
         be paid by the  Issuer or, if paid by the  Trustee  or any  predecessor
         trustee, shall be repaid by the Issuer upon demand;

                  (g) the  Trustee  may  execute  any of the  trusts  or  powers
         hereunder  or perform  any duties  hereunder  either  directly or by or
         through agents or attorneys not

                                      -42-
<PAGE>

         regularly in its employ and the Trustee  shall not be  responsible  for
         any  misconduct or negligence on the part of any such agent or attorney
         appointed with due care by it hereunder;

                  (h) the  Trustee  shall not be  deemed  to have  notice of any
         Default or Event of Default unless a Responsible Officer of the Trustee
         has  actual  knowledge  thereof or unless  written  notice of any event
         which is in fact such a  default  is  received  by the  Trustee  at the
         Corporate Trust Office of the Trustee,  and such notice  references the
         Securities and this Indenture; and

                  (i)  the  rights,  privileges,   protections,  immunities  and
         benefits given to the Trustee, including, without limitation, its right
         to be  indemnified,  are extended to, and shall be enforceable  by, the
         Trustee  in  each  of its  capacities  hereunder,  and to  each  agent,
         custodian and other Person employed to act hereunder.

                  SECTION 5.3 Trustee Not Responsible for Recitals,  Disposition
of Securities or Application of Proceeds Thereof.  The recitals contained herein
and in the Securi ties,  except the Trustee's  certificates  of  authentication,
shall be taken as the  statements  of the  Issuer,  and the  Trustee  assumes no
responsibility   for  the   correctness  of  the  same.  The  Trustee  makes  no
representation  as to the validity or  sufficiency  of this  Indenture or of the
Securi ties. The Trustee shall not be accountable  for the use or application by
the Issuer of any of the Securities or of the proceeds thereof.

                  SECTION   5.4   Trustee   and  Agents  May  Hold   Securities;
Collections,  etc. The Trustee or any agent of the Issuer or the Trustee, in its
individual or any other capacity,  may become the owner or pledgee of Securities
with the same rights it would have if it were not the Trustee or such agent and,
subject to Section 5.8, may otherwise deal with the Issuer and receive, collect,
hold and retain

                                      -43-
<PAGE>

collections  from the Issuer  with the same  rights it would have if it were not
the Trustee or such agent.

                  SECTION 5.5  Compensation and  Indemnification  of Trustee and
Its Prior Claim. The Issuer covenants and agrees to pay to the Trustee from time
to time, and the Trustee shall be entitled to, such  compensation as the Company
and the Trustee  shall from time to time agree in writing for all services  that
the Trustee shall provide hereunder (which  compensation shall not be limited by
any  provision of law in regard to the  compensation  of a trustee of an express
trust) and the Issuer  covenants  and agrees to pay or reimburse the Trustee and
each  predecessor  Trustee  upon  its  request  for  all  reasonable   expenses,
disbursements  and advances incurred or made by or on behalf of it in accordance
with any of the provisions of this Indenture (including the compensation and the
expenses and  disbursements  of its counsel and of all agents and other  persons
not regularly in its employ) except any such expense, disbursement or advance as
may arise  from its  negligence  or bad  faith.  The Issuer  also  covenants  to
indemnify the Trustee and each predecessor  Trustee for, and to hold it harmless
against,  any loss, damage,  claim,  liability or expense including taxes (other
than taxes based upon,  measured by or determined by the income of the Trustee),
incurred  without  negligence  or bad  faith on its part,  arising  out of or in
connection with the acceptance or administration of this Indenture or the trusts
hereunder and its duties  hereunder,  including but not limited to the costs and
expenses  of  defending  itself  against  or  investigating  any claim  (whether
asserted  by the  Company,  any  Holder or any other  Person)  or  liability  in
connection  with the  exercise  or  performance  of any of its  powers or duties
hereunder.  The  obligations  of the Issuer under this Section to compensate and
indemnify the Trustee and each  predecessor  Trustee and to pay or reimburse the
Trustee and each predecessor  Trustee for expenses,  disbursements  and advances
shall  constitute  additional  indebtedness  hereunder  and  shall  survive  the
satisfaction and discharge of this Indenture. Such additional indebtedness shall
be a senior claim to that of the Securities  upon all property and funds held or
collected by the Trustee as such, except funds held in trust

                                      -44-
<PAGE>

for the payment of principal of or interest on  particular  Securities,  and the
Securities are hereby subordinated to such senior claim. When the Trustee incurs
expenses or renders services in connection with an Event of Default specified in
Section 4.1 or in connection with Article Four hereof,  the expenses  (including
the reasonable  fees and expenses of its counsel) and the  compensation  for the
service  in  connection   therewith  are  intended  to  constitute  expenses  of
administration under any bankruptcy law.

                  SECTION 5.6 Right of Trustee to Rely on Officers' Certificate,
etc.  Subject to Sections  5.1 and 5.2,  whenever in the  administration  of the
trusts of this Indenture the Trustee shall deem it necessary or desirable that a
matter be proved or  established  prior to taking or  suffering  or omitting any
action hereunder, such matter unless other evidence in respect thereof be herein
specifically  prescribed)  may, in the absence of negligence or bad faith on the
part of the Trustee,  be deemed to be conclusively  proved and established by an
Officers'  Certificate  delivered to the Trustee,  and such certificate,  in the
absence of  negligence  or bad faith on the part of the  Trustee,  shall be full
warrant to the Trustee for any action taken, suffered or omitted by it under the
provisions of this Indenture upon the faith thereof.

                  SECTION 5.7 Persons  Eligible for Appointment as Trustee.  The
Trustee  hereunder  shall at all  times be a  corporation  organized  and  doing
business  under the laws of the United  States of America or of any State or the
District of Columbia.  The Trustee and its direct parent shall at all times have
a combined capital and surplus of at least $50,000,000,  and which is authorized
under such laws to exercise corporate trust powers and is subject to supervision
or  examination  by Federal,  State or District of Columbia  authority.  If such
corporation publishes reports of condition at least annually, pursuant to law or
to the requirements of the aforesaid  supervising or examining  authority,  then
for the  purposes  of this  Section,  the  combined  capital and surplus of such
corporation  shall be deemed to be its combined capital and surplus as set forth
in its most recent  report of  condition so  published.  In

                                      -45-
<PAGE>

case at any time the Trustee shall cease to be eligible in  accordance  with the
provisions of this Section,  the Trustee shall resign  immediately in the manner
and with the effect specified in Section 5.8.

                  The  provisions of this Section 5.7 are in  furtherance of and
subject to Section 310(a) of the TIA.

                  SECTION 5.8 Resignation and Removal;  Appointment of Successor
Trustee.  (a) The  Trustee may at any time  resign by giving  written  notice of
resignation to the Issuer. Upon receiving such notice of resignation, the Issuer
shall promptly appoint a successor  trustee by written  instrument in duplicate,
executed by authority  of the Board of  Directors,  one copy of each  instrument
shall be  delivered  to the  resigning  Trustee  and one  copy to the  successor
trustee.  If no successor trustee shall have been so appointed and have accepted
appointment  within 30 days after the giving of such notice of resignation,  the
resigning  trustee may  petition  any court of  competent  jurisdiction  for the
appointment of a successor  trustee,  or any Security holder who has been a bona
fide Holder of a Security or Securities for at least six months may,  subject to
the  provisions of Section  4.12, on behalf of himself and all others  similarly
situated,  petition any such court for the appointment of a successor trustee at
the expense of the Issuer. Such court may thereupon,  after such notice, if any,
as it may deem proper and prescribe, appoint a successor trustee.

                  (b) If at any time any of the following shall occur:

                (i) the  Trustee  shall fail to comply  with the pro  visions of
         Section 310(b) of the TIA after written request  therefor by the Issuer
         or by any  Securityholder who has been a bona fide Holder of a Security
         or Securities for at least six months; or

               (ii) the Trustee  shall cease to be eligible in  accordance  with
         the  provisions  of Section 5.7 and shall

                                      -46-
<PAGE>

         fail to resign after written  request  therefor by the Issuer or by any
         Securityholders;

              (iii) the Trustee  shall became  incapable of acting,  or shall be
         adjudged a bankrupt or  insolvent,  or a receiver or  liquidator of the
         Trustee or of its property  shall be appointed,  or any public  officer
         shall  take  charge or control of the  Trustee  or of its  property  or
         affairs for the purpose of rehabilitation, conservation or liquidation;

then,  in any such  case,  the  Issuer may  remove  the  Trustee  and  appoint a
successor trustee by written instrument, in duplicate,  executed by order of the
Board  of  Directors  of the  Issuer,  one  copy of  which  instrument  shall be
delivered to the Trustee so removed and one copy to the  successor  trustee,  or
subject to the  provisions of Section 4.12,  any  Securityholder  who has been a
bona fide  Holder of a  Security  or  Securities  for at least six months may on
behalf of  himself  and all others  similarly  situated,  petition  any court of
competent  jurisdiction  for the removal of the Trustee and the appointment of a
successor  trustee.  Such court may thereupon,  after such notice, if any, as it
may deem  proper and  prescribe,  remove the  Trustee  and  appoint a  successor
trustee.

                  (c) The Holders of a majority in aggregate principal amount of
the  Securities at the time  Outstanding  may at any time remove the Trustee and
appoint a successor  trustee by  delivering  to the  Trustee so removed,  to the
successor  trustee so appointed  and to the Issuer the evidence  provided for in
Section 6.1 of the action in that regard taken by the Securityholders.

                  (d)  Any  resignation  or  removal  of  the  Trustee  and  any
appointment  of a successor  trustee  pursuant to any of the  provisions of this
Section  5.8 shall  become  effective  upon  acceptance  of  appointment  by the
successor trustee as provided in Section 5.9.

                  (e) The Issuer shall give notice of each resigna tion and each
removal of the Trustee and each  appointment  of

                                      -47-
<PAGE>

a successor trustee by mailing written notice of such event by first-class mail,
postage  prepaid,  to the  Holders of  Securities  affected  as their  names and
addresses appear in the Security register. Each notice shall include the name of
the successor trustee and the address of its principal corporate trust office.

                  SECTION 5.9  Acceptance of  Appointment by Succes sor Trustee.
Any  successor  trustee  appointed as provided in Section 5.8 shall  execute and
deliver to the Issuer and to its  predecessor  trustee an  instrument  accepting
such  appointment  hereunder,  and thereupon the  resignation  or removal of the
predecessor  trustee shall become effective and such successor trustee,  without
any  further  act,  deed or  conveyance,  shall  become  vested with all rights,
powers, duties and obligations of its predecessor hereunder, with like effect as
if originally named as trustee herein; but, nevertheless, on the written request
of the Issuer or of the  successor  trustee,  upon  payment of its charges  then
unpaid,  the trustee  ceasing to act shall,  subject to Section 9.4, pay over to
the  successor  trustee  all moneys at the time held by it  hereunder  and shall
execute and deliver an instrument  prepared by the Issuer  transferring  to such
successor trustee all such rights, powers, duties and obligations.  Upon request
of any such successor trustee,  the Issuer shall execute any and all instruments
in  writing  for more fully and  certainly  vesting  in and  confirming  to such
successor trustee all such rights and powers.  Any trustee ceasing to act shall,
nevertheless,  retain a prior claim upon all property or funds held or collected
by such trustee to secure any amounts then due it pursuant to the  provisions of
Section 5.5.

                  Upon  acceptance  of  appointment  by a  successor  trustee as
provided  in  this  Section  5.9,  the  Issuer  shall  mail  notice  thereof  by
first-class  mail to the Holders of Securities  at their last  addresses as they
shall appear in the Security  register.  If the  acceptance  of  appointment  is
substantially  contemporaneous with the resignation,  then the notice called for
by the preceding  sentence may be combined with the notice called for by Section
5.8. If the Issuer fails to mail such notice within 10 days after  acceptance of

                                      -48-
<PAGE>


appointment  by the successor  trustee,  the successor  trustee shall cause such
notice to be mailed at the expense of the Issuer.

                  SECTION 5.10 Merger,  Conversion,  Consolidation or Succession
to Business of Trustee.  Any corporation into which the Trustee may be merged or
converted or with which it may be  consolidated,  or any  corporation  resulting
from any merger,  conversion  or  consolidation  to which the Trustee shall be a
party,  or any  corporation  succeeding to the cor porate trust  business of the
Trustee,  shall be the successor of the Trustee  hereunder without the execution
or  filing  of any paper or any  further  act on the part of any of the  parties
hereto,  anything  herein to the contrary  notwithstanding;  provided  that such
corporation shall be qualified under the provisions of Section 310(b) of the TIA
and eligible under the provisions of Section 5.7.

                  In  case at the  time  such  successor  to the  Trustee  shall
succeed to the trusts created by this Indenture any of the Securities shall have
been  authenticated  but not  delivered,  any such  successor to the Trustee may
adopt the certificate of authentication  of any predecessor  trustee and deliver
such  Securities  so  authenticated;  and,  in  case  at  that  time  any of the
Securities shall not have been authen ticated,  any successor to the Trustee may
authenticate such Securities either in the name of any predecessor  hereunder or
in the name of the  successor  trustee;  and in all such cases such  certificate
shall have the full force  which it is  anywhere  in the  Securities  or in this
Indenture provided that the certificate of the Trustee shall have; provided that
the right to adopt the certificate of authentication of any predecessor  trustee
or to  authenticate  Securities  of any  series  in the name of any  predecessor
trustee shall apply only to its successor or successors by merger, conversion or
consolidation.


                                      -49-
<PAGE>


                                   ARTICLE SIX

                         CONCERNING THE SECURITYHOLDERS

                  SECTION 6.1 Evidence of Action Taken by Security holders.  Any
request,  demand,  authorization,  direction,  notice,  consent, waiver or other
action provided by this Indenture to be given or taken by Securityholders may be
embodied in and evidenced by one or more  instruments of  substantially  similar
tenor signed by such  Securityholders in person or by an agent duly appointed in
writing;  and, except as herein otherwise expressly provided,  such action shall
become  effective  when such  instrument  or  instruments  are  delivered to the
Trustee.  Proof of execution of any such  instrument or of a writing  appointing
any such  agent  shall be  sufficient  for any  purpose  of this  Indenture  and
(subject to  Sections  5.1 and 5.2)  conclusive  in favor of the Trustee and the
Issuer, if made in the manner provided in this Article.

                  SECTION 6.2 Proof of Execution of  Instruments  and of Holding
of  Securities.  Subject  to  Sections  5.1 and  5.2,  the  fact and date of the
execution of any instrument by any  Securityholder or his agent or proxy, or the
authority of such an agent or proxy to execute such an instrument  may be proved
(i) by the affidavit of a witness of such execution,  (ii) by a certificate of a
notary public (or other officer  authorized  by law to take  acknowledgments  of
deeds) as to such execution,  or (iii) in accordance with such reasonable  rules
and  regulations  as may be prescribed by the Trustee or in such manner as shall
be reasonably  satisfactory to the Trustee.  The holding of Securities  shall be
proved by the Security register or by a certificate of the registrar thereof.

                  SECTION  6.3  Holders to Be  Treated  as Owners.  Prior to due
presentment of a Security for registration of transfer, the Issuer, the Trustee,
any  Agent and any agent of the  Issuer  or the  Trustee  may deem and treat the
person in whose name any Security shall be registered upon the Security register
as the absolute  owner of such Security  (whether or not such Security  shall be
overdue and

                                      -50-
<PAGE>

notwithstanding  any  notation of ownership  or other  writing  thereon) for the
purpose of receiving  payment of or on account of the principal of and,  subject
to the provisions of this Indenture, interest on such Security and for all other
purposes;  and  neither the Issuer nor the Trustee nor any Agent or agent of the
Issuer or the Trustee shall be affected by any notice to the contrary.  All such
payments so made to any such person, or upon his order,  shall be valid, and, to
the extent of the sum or sums so paid,  effectual to satisfy and  discharge  the
liability for moneys payable upon any such Security.

                  SECTION 6.4 Securities Owned by Issuer Deemed Not Outstanding.
In  determining  whether  the  Holders  of the  requisite  principal  amount  of
Outstanding Securities have concurred in any direction,  consent or waiver under
this Indenture, Securities which are owned by the Issuer or any other obligor on
the  Securities or any Affiliate of the Issuer or of such other obligor shall be
disregarded  and  deemed  not to be  Outstanding  for the  purpose  of any  such
determination,  except that for the purpose of  determining  whether the Trustee
shall be  protected  in relying on any such  direction,  consent or waiver  only
Securities which the Trustee knows are so owned shall be so disregarded.  Securi
ties so  owned  which  have  been  pledged  in good  faith  may be  regarded  as
Outstanding  if the pledgee  establishes to the  satisfaction  of the Trustee in
writing the pledgee's  right so to act with respect to such  Securities and that
the pledgee is not the Issuer or any other  obligor upon the  Securities  or any
Affiliate  of the  Issuer or of such other  obligor.  In case of a dispute as to
such right,  the advice of counsel  shall be full  protection  in respect of any
decision made by the Trustee in accordance with such advice. Upon request of the
Trustee,  the  Issuer  shall  furnish  to  the  Trustee  promptly  an  Officers'
Certificate listing and identifying all Securities,  if any, known by the Issuer
to be owned or held by or for the account of any of the above-described Persons;
and,  subject to Sections 5.1 and 5.2,  the Trustee  shall be entitled to accept
such Officers' Certificate as conclusive evidence of the facts therein set forth
and of the fact that all Securities not listed therein are  Outstanding  for the
purpose of any such determination.

                                      -51-
<PAGE>

                  SECTION 6.5 Right of Revocation  of Action Taken.  At any time
prior to (but not after) the  evidencing to the Trustee,  as provided in Section
6.1, of the taking of any action by the Holders of the  percentage  in aggregate
principal  amount of the  Securities  specified in this  Indenture in connection
with such action,  any Holder of a Security the serial  number of which is shown
by the evidence to be included  among the serial  numbers of the  Securities the
Holders of which have  consented to such action may, by filing written notice at
the  Corporate  Trust  Office  and upon proof of  holding  as  provided  in this
Article,  revoke such action so far as concerns such  Security.  Except as afore
said any such action taken by the Holder of any Security shall be conclusive and
binding upon such Holder and upon all future Holders and owners of such Security
and  of any  Securities  issued  in  exchange  or  substitution  therefor  or on
registration or transfer thereof, irrespective of whether or not any notation in
regard thereto is made upon any such  Security.  Any action taken by the Holders
of the percentage in aggregate  principal amount of the Securities  specified in
this Indenture in connection with such action shall be conclusively binding upon
the Issuer, the Trustee and the Holders of all the Securities.

                  SECTION 6.6 Record Date for Consents  and Waivers.  The Issuer
may,  but shall not be  obligated  to,  direct the Trustee to establish a record
date for the purpose of determining  the Persons  entitled to (i) waive any past
default with respect to the  Securities  in accordance  with Section 4.10,  (ii)
consent to any  supplemental  indenture in accordance  with Section 7.2 or (iii)
waive compliance with any term, condition or provision of any covenant hereunder
(if the Indenture should expressly provide for such waiver). If a record date is
fixed,  the Holders of Securities on such record date, or their duly  designated
proxies, and any such Persons, shall be entitled to waive any such past default,
consent to any such  supplemental  indenture or waive  compliance  with any such
term, condition or provision,  whether or not such Holder remains a Holder after
such  record  date;  provided,  however,  that  unless such waiver or consent is
obtained  from  the  Holders,  or  duly  designated  proxies,  of the  requisite
principal  amount of Outstanding

                                      -52-
<PAGE>

Securities  prior to the date which is the 90th day after such record date,  any
such waiver or consent previously given shall  automatically and without further
action by any Holder be cancelled and of no further effect.


                                  ARTICLE SEVEN

                             SUPPLEMENTAL INDENTURES

                  SECTION  7.1  Supplemental   Indentures   Without  Consent  of
Securityholders.  The Issuer,  when  authorized  by a resolution of its Board of
Directors,  and the  Trustee may from time to time and at any time enter into an
indenture  or  indentures  supplemental  hereto  (which  shall  conform  to  the
provisions of the TIA as in force at the date of the execution  thereof) for one
or more of the following purposes:

                  (a) to convey,  transfer,  assign,  mortgage  or pledge to the
         Trustee as security for the Securities any property or assets;

                  (b) to evidence the  succession of another  corporation to the
         Issuer, or successive successions,  and the assumption by the successor
         corporation of the covenants,  agreements and obligations of the Issuer
         pursuant to Article Eight;

                  (c) to  add  to the  covenants  of  the  Issuer  such  further
         covenants,  restrictions,  conditions or provisions  (including without
         limitation  provisions necessary or desirable to qualify this Indenture
         under the TIA) as its Board of Directors and the Trustee shall consider
         to be for the protection or benefit of the Holders of  Securities,  and
         to make the occurrence, or the occurrence and continuance, of a default
         in  any  such  additional

                                      -53-
<PAGE>

         covenants,  restrictions,  conditions or provisions an Event of Default
         permitting  the  enforcement  of all or  any  of the  several  remedies
         provided  in this  Indenture  as herein  set  forth;  provided  that in
         respect of any such  additional  covenant,  restriction,  condition  or
         provision  such  supplemental  indenture  may provide for a  particular
         period of grace after  default  (which  period may be shorter or longer
         than that allowed in the case of other  defaults) or may provide for an
         immediate  enforcement  upon such an Event of  Default or may limit the
         remedies  available to the Trustee upon such an Event of Default or may
         limit the right of the  Holders of a majority  in  aggregate  principal
         amount of the Securities to waive such an Event of Default;

                  (d) to cure any  ambiguity  or to  correct or  supplement  any
         provision  contained herein or in any supplemental  indenture which may
         be defective or inconsistent with any other provision  contained herein
         or in any  supplemental  indenture  or to make such other  provision in
         regard to matters or questions  arising  under this  Indenture or under
         any supplemental indenture as the Board of Directors may deem necessary
         or desirable,  provided that no such action shall adversely  affect the
         interests of the Holders of the Securities;

                  (e) to provide for adjustment of conversion rights pursuant to
         Section 12.5; or

                  (f) to evidence the removal or  resignation of the Trustee and
         the appointment of a successor  Trustee or Trustees pursuant to Article
         Five.

                  The Trustee is hereby  authorized  to join in the execution of
any such supplemental  indenture, to make any further appropriate agreements and
stipulations,  which may be therein  contained,  and to accept  the  conveyance,
transfer,  assignment,  mortgage or pledge of any property  thereunder,  but the
Trustee  shall not be  obligated to enter into any such  supplemental  indenture
which  affects  adversely  the  Trustee's  own  rights,  duties,  immunities  or
liabilities under this Indenture or otherwise.

                  Any  supplemental  indenture  authorized by the  provisions of
this  Section 7.1 may be  executed  without the

                                      -54-
<PAGE>

consent  of  the  Holders  of any of the  Securities  at the  time  Outstanding,
notwithstanding any of the provisions of Section 7.2.

                  SECTION   7.2   Supplemental   Indentures   with   Consent  of
Securityholders.  With the consent (evidenced as provided in Article Six) of the
Holders  of not less  than a  majority  in  aggregate  principal  amount  of the
Securities at the time Outstanding,  the Issuer, when authorized by a resolution
of its Board of  Directors,  and the Trustee  may,  from time to time and at any
time,  enter into an indenture or  indentures  supplemental  hereto (which shall
conform  to the  provisions  of the TIA as in  force  at the  date of  execution
thereof) for the purpose of adding any  provisions  to or changing in any manner
or eliminating  any of the  provisions of this Indenture or of any  supplemental
indenture  or of  modifying  in any  manner  the  rights of the  Holders  of the
Securities;  provided that no such  supplemental  indenture shall (a) extend the
final  maturity  of any  Security,  or reduce the  principal  amount  thereof or
premium,  if any,  thereon,  or reduce the rate or extend the time of payment of
interest thereon,  or any premium payable upon the redemption thereof, or change
the place of payment  where,  or the coin or currency in which,  any  principal,
premium or interest is payable,  or reduce or alter the method of calculation of
any amount payable on redemption,  repurchase or repayment  thereof (or the time
at which any such redemption, repurchase or repayment may be made), or impair or
adversely  affect  the right of any  Securityholder  to  institute  suit for the
payment or  conversion  thereof  or  adversely  affect the right to convert  the
Securities in accordance with Article Twelve, in each case,  without the consent
of the Holder of each Security so affected; provided no consent of any Holder of
any Security shall be necessary under this Section 7.2 to permit the Trustee and
the Issuer to execute  supplemental  indentures  pursuant to Section  7.1(e) and
Section  12.5 of this  Indenture;  or (b) reduce  the  aforesaid  percentage  in
principal amount of Outstanding Securities,  the consent of the Holders of which
is  required  for any such  supplemental  indenture,  without the consent of the
Holders of each Security so affected; or (c) reduce the percentage of Securities
necessary to consent to waive any past default

                                      -55-
<PAGE>

under this Indenture to less than a majority, without the consent of the Holders
of each  Security  so  affected;  or (d)  modify any of the  provisions  of this
Section or Section  4.10,  except to increase  any such  percentage  provided in
either  such  Section  or to  provide  that  certain  other  provisions  of this
Indenture cannot be modified or waived without the consent of the Holder of each
Security affected thereby.

                  Upon the  request of the  Issuer,  accompanied  by a copy of a
resolution of the Board of Directors (which resolution may provide general terms
or  parameters  for such action and may provide that the specific  terms of such
action may be  determined in  accordance  with or pursuant to an Issuer  Order),
certified by the Secretary or an Assistant Secretary of the Issuer,  authorizing
the execution of any such supplemental  indenture,  and upon the filing with the
Trustee of evidence of the consent of  Securityholders  and other documents,  if
any,  required by Section  6.1,  the  Trustee  shall join with the Issuer in the
execution of such  supplemental  indenture  unless such  supplemental  indenture
adversely  affects the Trustee' own rights,  duties,  immunities or  liabilities
under  this  Indenture  or  otherwise,  in  which  case the  Trustee  may in its
discretion,  but  shall  not be  obligated  to,  enter  into  such  supplemental
indenture.

                  It  shall   not  be   necessary   for  the   consent   of  the
Securityholders  under  this  Section  to  approve  the  particular  form of any
proposed  supplemental  indenture,  but it shall be  sufficient  if such consent
shall approve the substance thereof.

                  Promptly  after the execution by the Issuer and the Trustee of
any  supplemental  indenture  pursuant to the  provisions of this  Section,  the
Issuer  shall  mail a notice  thereof  by  first-class  mail to the  Holders  of
Securities at their  addresses as they shall appear on the registry books of the
Issuer,  setting  forth in  general  terms the  substance  of such  supplemental
indenture. Any failure of the Issuer to mail such notice, or any defect therein,
shall  not,  however,  in any way  impair or  affect  the  validity  of any such
supplemental indenture.

                                      -56-
<PAGE>

                  SECTION  7.3  Effect  of  Supplemental  Indenture.   Upon  the
execution of any supplemental  indenture pursuant to the provisions hereof, this
Indenture  shall be and be deemed  to be  modified  and  amended  in  accordance
therewith and the respective rights, limitations of rights, obligations,  duties
and immunities  under this Indenture of the Trustee,  the Issuer and the Holders
of Securities shall thereafter be determined,  exercised and enforced  hereunder
subject in all respects to such modifications and amendments,  and all the terms
and conditions of any such  supplemental  indenture shall be and be deemed to be
part of the terms and conditions of this Indenture for any and all purposes.

                  SECTION 7.4  Documents  to be Given to Trustee.  The  Trustee,
subject to the  provisions of Sections 5.1 and 5.2, may upon request  receive an
Officers'  Certificate and an Opinion of Counsel as conclusive evidence that any
such  supplemental  indenture  complies with the  applicable  provisions of this
Indenture.

                  SECTION 7.5 Notation on Securities in Respect of  Supplemental
Indentures.  Securities  authenticated  and delivered after the execution of any
supplemental  indenture  pursuant to the  provisions  of this Article may bear a
notation as to any matter provided for by such  supplemental  indenture.  If the
Issuer shall so  determine,  new  Securities  so modified as to conform,  in the
opinion  of the  Board  of  Directors,  to any  modification  of this  Indenture
contained  in any such  supplemental  indenture  may be  prepared by the Issuer,
authenticated  by the Trustee and delivered in exchange for the Securities  then
Outstanding.


                                  ARTICLE EIGHT

                    CONSOLIDATION, MERGER, SALE OR CONVEYANCE

                  SECTION 8.1 Covenant Not to Merge, Consolidate, Sell or Convey
Property  Except Under Certain  Conditions.  The Issuer may not  consolidate  or
merge with or into (whether or not the Issuer is the Surviving Person), or sell,
assign, transfer, lease, convey or otherwise dispose of all or

                                      -57-
<PAGE>

substantially   all  of  its  properties  or  assets  in  one  or  more  related
transactions, to another Person (each a "Disposition"), unless:

         (i) the Surviving  Person is a corporation  organized or existing under
         the laws of the United  States,  any state  thereof or the  District of
         Columbia;

         (ii) the  Surviving  Person (if other than the Issuer)  assumes all the
         obligations of the Issuer under the Securities and this Indenture,  and
         makes provision for conversion  rights in accordance with Section 12.5,
         pursuant to a supplemental indenture in a form reasonably  satisfactory
         to the Trustee; and

         (iii) immediately after such Disposition,  no Event of Default or event
         that,  after the giving of notice or the passage of time or both, would
         be an Event of Default, shall have occurred and be continuing.

                  SECTION 8.2 Successor  Corporation or Entity  Substituted.  In
case of any such consolidation,  merger, sale or conveyance,  and following such
an assumption by the successor  corporation,  partnership  or limited  liability
company,  such successor  corporation,  partnership or limited liability company
shall succeed to and be substituted  for the Issuer,  with the same effect as if
it had been named herein.

                  Such successor  corporation,  partnership or limited liability
company may cause to be signed,  and may issue  either in its own name or in the
name  of the  Issuer  prior  to  such  succession  any or all of the  Securities
issuable  hereunder which  theretofore  shall not have been signed by the Issuer
and delivered to the Trustee; and, upon the order of such successor corporation,
partnership or limited liability company,  instead of the Issuer, and subject to
all the terms,  conditions and  limitations in this  Indenture  prescribed,  the
Trustee shall authenticate and shall deliver


                                      -58-
<PAGE>

any  Securities  which  previously  shall have been signed and  delivered by the
officers  of the Issuer to the Trustee for  authentication,  and any  Securities
which such  successor  corporation,  partnership  or limited  liability  company
thereafter  shall  cause to be signed  and  delivered  to the  Trustee  for that
purpose.  All of the  Securities  so issued shall in all respects  have the same
legal rank and benefit under this  Indenture as the  Securities  theretofore  or
thereafter  issued in accordance  with the terms of this Indenture as though all
of such Securities had been issued at the date of the execution hereof.

                  In case of any  such  consolidation,  merger,  sale,  lease or
conveyance,  such changes in phraseology  and form (but not in substance) may be
made in the Securities thereafter to be issued as may be appropriate.

                  In the  event of any such  sale or  conveyance  (other  than a
conveyance  by  way  of  lease),  the  Issuer  or  any  successor   corporation,
partnership or limited  liability  company which shall  theretofore  have become
such in the  manner  described  in this  Article  shall be  discharged  from all
obligations  and covenants  under this  Indenture and the  Securities and may be
liquidated and dissolved.

                  SECTION 8.3 Opinion of Counsel and  Officers'  Certificate  to
Trustee.  The Trustee,  subject to the  provisions  of Sections 5.1 and 5.2, may
upon request  receive an Opinion of Counsel  prepared in accordance with Section
10.5 and an Officers' Certificate (confirming  satisfaction of the conditions of
clauses (i), (ii) and (iii) of Section 8.1) as conclusive evidence that any such
consolidation,  merger, sale, lease or conveyance,  and any such assumption, and
any such liquidation or dissolution,  complies with the applicable provisions of
this Indenture.


                                      -59-
<PAGE>

                                  ARTICLE NINE

                           SATISFACTION AND DISCHARGE
                         OF INDENTURE; UNCLAIMED MONEYS

                  SECTION 9.1 Satisfaction and Discharge of Indenture. If at any
time (a) the Issuer  shall have paid or caused to be paid the  principal  of and
premium, if any, and interest on all the Securities then Outstanding  hereunder,
as and when the same shall have become due and payable,  or (b) the Issuer shall
have  delivered  to the  Trustee for  cancellation  all  Securities  theretofore
authenticated  (other than any Securities which shall have been destroyed,  lost
or stolen and which shall have been replaced or paid as provided in Section 2.7)
or (c) (i) all such  Securities  not  theretofore  delivered  to the Trustee for
cancellation (x) shall have become due and payable, or (y) are by their terms to
become due and payable within one year or are to be called for redemption within
one year under  arrangements  reasonably  satisfactory  to the  Trustee  for the
giving of notice of  redemption,  and (ii) the  Issuer  shall  have  irrevocably
deposited or caused to be  deposited  with the Trustee as trust funds the entire
amount in cash (other than moneys  repaid by the Trustee or any Paying  Agent to
the  Issuer in  accordance  with  Section  9.4) or U.S.  Government  Obligations
maturing as to principal  and interest at such times and in such amounts as will
insure the  availability  of cash, or a combination  thereof,  sufficient in the
opinion  of a  nationally  recognized  firm of  independent  public  accountants
expressed in a written  certification  thereof delivered to the Trustee,  to pay
the principal of and interest on all Securities on each date that such principal
or interest is due and payable;  and if, in any such case, the Issuer shall also
pay or cause to be paid all other sums  payable  hereunder  by the Issuer,  then
this  Indenture  shall cease to be of further effect (except as to (i) rights of
registration  of  transfer,  conversion  and  exchange  of  Securities,  and the
Issuer's right of optional  redemption  contemplated  in clause  (c)(i)(y) above
(but not  otherwise  and not  including  the  Holders'  right of  redemption  or
repurchase   contemplated  by  Article  Thirteen  or  Article  Fourteen),   (ii)
substitution  of  apparently  mutilated,

                                      -60-
<PAGE>

defaced,  destroyed,  lost or stolen Securities,  (iii) rights of the Holders of
Securities  to receive  payments of principal  thereof and  premium,  if any and
interest  thereon  upon the  original  stated due dates  therefor  (but not upon
acceleration),  (iv) the  rights,  obligations  and  immunities  of the  Trustee
hereunder, including any right to compensation and indemnification under Section
5.5, and (v) the rights of the Holders of  Securities  as  beneficiaries  hereof
with respect to the property so deposited with the Trustee payable to all or any
of  them),  and  the  Trustee,  on  Issuer  Order  accompanied  by an  Officers'
Certificate  and an Opinion  of  Counsel  stating  that the  provisions  of this
Section have been complied with and at the cost and expense of the Issuer, shall
execute  proper   instruments   prepared  by  the  Issuer   acknowledging   such
satisfaction of and discharging  this  Indenture,  provided,  that the rights of
Holders of the  Securities  to receive  amounts  in  respect  of  principal  of,
premium,  if any,  and  interest  on the  Securities  held by them  shall not be
delayed longer than required by  then-applicable  mandatory rules or policies of
any securities  exchange upon which the Securities are listed.  In addition,  in
connection  with the  satisfaction  and discharge  pursuant to clause  (c)(i)(y)
above,  the  Trustee  shall give  notice to the  Holders of  Securities  of such
satisfaction  and discharge.  The Issuer agrees to reimburse the Trustee for any
costs or expenses thereafter  reasonably and properly incurred and to compensate
the Trustee for any services thereafter  reasonably and properly rendered by the
Trustee in connection with this Indenture or the Securities.

                  Notwithstanding   the   satisfaction  and  discharge  of  this
Indenture,  the obligations of the Issuer to the Trustee under Section 5.5 shall
survive.

                  SECTION  9.2  Application  by Trustee of Funds  Deposited  for
Payment  of  Securities.  Subject  to Section  9.4,  all  moneys and  securities
deposited  with the  Trustee  pursuant to Section 9.1 shall be held in trust and
applied  by it to the  payment,  either  directly  or through  any Paying  Agent
(including  the Issuer  acting as its own Paying  Agent),  to the Holders of the
particular  Securities  for the

                                      -61-
<PAGE>


payment or  redemption of which such moneys or  Securities  have been  deposited
with the  Trustee of all sums due and to become due thereon  for  principal  and
interest;  but such moneys or securities need not be segregated from other funds
except to the extent required by law.

                  SECTION  9.3  Repayment  of Moneys  Held by Paying  Agent.  In
connection with the satisfaction and discharge of this Indenture with respect to
Securities,  all moneys then held by any Paying  Agent under the  provisions  of
this Indenture shall,  upon Issuer Order, be repaid to it or paid to the Trustee
and  thereupon  such Paying Agent shall be released  from all further  liability
with respect to such moneys.

                  SECTION 9.4 Return of Moneys Held by Trustee and Paying  Agent
Unclaimed for Two Years. Any moneys deposited with or paid to the Trustee or any
Paying Agent for the payment of the principal of or premium, if any, or interest
on any Security and not applied but remaining  unclaimed for two years after the
date upon which such  principal,  premium or interest  shall have become due and
payable  shall,  upon the  written  request of the  Issuer and unless  otherwise
required by mandatory provisions of applicable escheat or abandoned or unclaimed
property law, be repaid to the Issuer by the Trustee or such Paying  Agent,  and
the Holder of the  Securities  shall,  unless  otherwise  required by  mandatory
provisions  of  applicable  escheat or  abandoned or  unclaimed  property  laws,
thereafter  look only to the Issuer  for any  payment  which such  Holder may be
entitled to collect,  and all  liability of the Trustee or any Paying Agent with
respect to such  moneys  shall  thereupon  cease;  provided,  however,  that the
Trustee or such Paying Agent,  before being  required to make any such repayment
with respect to moneys deposited with it for any payment,  shall, at the expense
of the Issuer,  mail by first-class  mail to Holders of such Securities at their
addresses as they shall appear on the Security  register notice that such moneys
remain and that, after a date specified therein, which shall not be less than 30
days from the date of such  mailing,  any  unclaimed  balance of such money then
remaining will be repaid to the Issuer upon Issuer Order.

                                      -62-
<PAGE>

                  SECTION 9.5 Indemnity  for U.S.  Government  Obligations.  The
Issuer shall pay and indemnify the Trustee  against any tax, fee or other charge
imposed  on or  assessed  against  the  U.S.  Government  Obligations  deposited
pursuant to Section 9.1 or the principal or interest received in respect of such
obligations.

                                   ARTICLE TEN

                            MISCELLANEOUS PROVISIONS

                  SECTION 10.1 Partners, Incorporators,  Stockholders,  Officers
and Directors of Issue Exempt from  Individual  Liability.  No recourse under or
upon any obliga tion, covenant or agreement  contained in this Indenture,  or in
any Security,  or because of any indebtedness  evidenced  thereby,  shall be had
against  any  incorporator,  as such,  or  against  any past,  present or future
stockholder,  officer or director,  as such,  of the Issuer or of any partner or
member of the Issuer or of any successor,  either directly or through the Issuer
or any successor,  under any rule of law, statute or constitutional provision or
by the enforcement of any assessment or by any legal or equitable  proceeding or
otherwise,  all such  liability  being  expressly  waived  and  released  by the
acceptance  of the  Securities  by  the  Holders  thereof  and  as  part  of the
consideration for the issue of the Securities.

                  SECTION 10.2  Provisions  of Indenture for the Sole Benefit of
Parties and  Securityholders.  Nothing in this  Indenture or in the  Securities,
expressed or implied,  shall give or be  construed to give to any Person,  other
than the parties hereto and their  successors and the Holders of the Securities,
any legal or equitable right,  remedy or claim under this Indenture or under any
covenant or provision herein contained,  all such covenants and provisions being
for the sole benefit of the parties hereto and their  successors and the Holders
of the Securities.

                  SECTION  10.3  Successors  and  Assigns  of  Issuer  Bound  by
Indenture.  All the  covenants,  stipulations,

                                      -63-
<PAGE>

promises  and  agreements  in this  Indenture  contained  by or on behalf of the
Issuer shall bind its successors and assigns, whether so expressed or not.

                  SECTION  10.4  Notices  and  Demands  on Issuer,  Trustee  and
Securityholders.  Any notice or demand which by any provision of this  Indenture
is required or  permitted to be given or served by the Trustee or by the Holders
of  Securities  to or on the  Issuer  may be given or served by being  deposited
postage  prepaid,  first-class mail (except as otherwise  specifically  provided
herein)  addressed  (until another  address of the Issuer is filed by the Issuer
with the Trustee) to American Tower Corporation,  116 Huntington Avenue, Boston,
MA  02116,  Attention:  Chief  Financial  Officer  and  Secretary.  Any  notice,
direction,  request or demand by the Issuer or any Securityholder to or upon the
Trustee  shall be  deemed  to have  been  sufficiently  given  or made,  for all
purposes, if given or made at the Corporate Trust Office,  Attention:  Corporate
Trust Trustee Administration Department.

                  Where this  Indenture  provides  for notice to  Holders,  such
notice shall be sufficiently  given (except as otherwise  specifically  provided
herein) if in writing,  and mailed,  first-class postage prepaid, to each Holder
entitled thereto, at his last address as it appears in the Security register. In
any case where  notice to Holders is given by mail,  neither the failure to mail
such notice,  nor any defect in any notice so mailed,  to any particular  Holder
shall affect the sufficiency of such notice with respect to other Holders. Where
this Indenture  provides for notice in any manner,  such notice may be waived in
writing by the Person  entitled to receive such notice,  either  before or after
the event,  and such waiver shall be the  equivalent of such notice.  Waivers of
notice by Holders shall be filed with the Trustee,  but such filing shall not be
a condition  precedent to the validity of any action taken in reliance upon such
waiver.

                  In case, by reason of the suspension of or irregu  larities in
regular mail service, it shall be impracticable to mail notice to the Issuer and
Securityholders  when  such

                                      -64-
<PAGE>

notice is required to be given pursuant to any provision of this Indenture, then
any manner of giving such notice as shall be  satisfactory  to the Trustee shall
be deemed to be a sufficient giving of such notice.

                  SECTION 10.5 Officers'  Certificates  and Opinions of Counsel;
Statements to Be Contained Therein. Upon any application or demand by the Issuer
to the Trustee to take any action under any of the provisions of this Indenture,
the Issuer shall  furnish to the Trustee an Officers'  Certificate  stating that
all conditions precedent provided for in this Indenture relating to the proposed
action have been  complied  with and an Opinion of Counsel  stating  that in the
opinion of such counsel all such  conditions  precedent have been complied with,
except  that in the case of any  such  application  or  demand  as to which  the
furnishing of such documents is  specifically  required by any provision of this
Indenture  relating to such  particular  application  or demand,  no  additional
certificate or opinion need be furnished.

                  Each certificate or opinion provided for in this Indenture and
delivered to the Trustee with respect to compliance with a condition or covenant
provided for in this  Indenture  shall  include (a) a statement  that the person
making such  certificate  or opinion has read such covenant or condition,  (b) a
brief statement as to the nature and scope of the  examination or  investigation
upon the  statements or opinions  contained in such  certificate  or opinion are
based,  (c) a statement  that,  in the opinion of such person,  he has made such
examination  or  investigation  as is  necessary  to enable  him to  express  an
informed  opinion as to  whether  or not such  covenant  or  condition  has been
complied  with, and (d) a statement as to whether or not, in the opinion of such
person, such condition or covenant has been complied with.

                  Any  certificate,  statement  or  opinion of an officer of the
Issuer may be based, insofar as it relates to legal matters,  upon a certificate
or opinion of or represen tations by counsel, unless such officer knows that the
certificate or opinion or representations with respect to the matters upon which
his  certificate,  statement or opinion may be based as aforesaid are erroneous,
or in the exercise

                                      -65-
<PAGE>

of reasonable  care should know that the same are  erroneous.  Any  certificate,
statement  or opinion of counsel may be based,  insofar as it relates to factual
matters,  information  with respect to which is in the possession of the Issuer,
upon the certificate,  statement or opinion of or representa tions by an officer
or officers  of the Issuer,  unless  such  counsel  knows that the  certificate,
statement or opinion or  representations  with respect to the matters upon which
his  certificate,  statement or opinion may be based as aforesaid are erroneous,
or in the exercise of reasonable care should know that the same are erroneous.

                  Any  certificate,  statement  or  opinion of an officer of the
Issuer or of counsel may be based,  insofar as it relates to accounting matters,
upon a certificate or opinion of or  representations by an accountant or firm of
accountants in the employ of the Issuer,  unless such officer or counsel, as the
case may be,  knows that the  certificate  or opinion  or  representations  with
respect to the  accounting  matters  upon which his  certificate,  statement  or
opinion  may  be  based  as  aforesaid  are  erroneous,  or in the  exercise  of
reasonable care should know that the same are erroneous.

                  Any certificate or opinion of any  independent  firm of public
accountants  filed with the Trustee shall contain a statement  that such firm is
independent.

                  SECTION  10.6  Payments  Due on  Saturdays,  Sundays and Legal
Holidays.  If the date of maturity of interest on or principal of the Securities
or the date fixed for redemp tion or  repayment of any Security or the last date
on which a Holder of Securities has a right to convert his Securities  shall not
be a Business Day, then  (notwithstanding  any other provision of this Indenture
or of the  Securities)  payment of interest or  principal or  conversion  of the
Securities need not be made on such date, but may be made on the next succeeding
Business  Day with the same force and effect as if made on the date of  maturity
or the  date  fixed  for  redemption  or  repayment  or on  such  last  day  for
conversion, and no interest shall accrue for the period after such date.

                                      -66-
<PAGE>

                  SECTION 10.7 Conflict with TIA. Whether or not qualified under
the TIA,  this  Indenture  shall be  interpreted  as though it were so qualified
including provisions required by the TIA or provisions deemed included except as
varied by this Indenture. If any provision hereof limits, qualifies or conflicts
with a provision  of the TIA that is required  under the TIA to be a part of and
govern this Indenture,  the latter provision shall control.  If any provision of
this  Indenture  modifies or excludes  any  provision  of the TIA that may be so
modified  or  excluded,  the latter  provision  shall be deemed to apply to this
Indenture as so modified or to be excluded, as the case may be.

                  SECTION 10.8  Communications  by Holders  with Other  Holders.
Securityholders may communicate pursuant to Section 312(b) of the TIA with other
Holders with respect to their rights under this Indenture or the Securities. The
Issuer,  the  Trustee,  the  Registrar  and any  other  person  shall  have  the
protection of Section 312(c) of the TIA.

                  SECTION 10.9 Issuer to Furnish  Trustee Names and Addresses of
Holders. The Issuer will furnish or cause to be furnished to the Trustee:

                  (a) semiannually,  not later than February 15 and August 15 in
         each year, a list, in such form as the Trustee may reasonably  require,
         of the names and addresses of the Securityholders as of a date not more
         than 15 days prior to the delivery thereof, and

                  (b) at such other times as the Trustee may request in writing,
         within 30 days after the receipt by the Issuer of any such  request,  a
         list of  similar  form and  content  as of a date not more than 15 days
         prior to the time such list is furnished;

excluding from any such list names and addresses  received by the Trustee in the
capacity of Registrar.

                  SECTION 10.10 New York Law to Govern.  This Indenture and each
Security  shall be  deemed to be a  contract  under the laws of the State of New
York,  and for all

                                      -67-
<PAGE>

purposes shall be construed in accordance  with the laws of said State,  without
regard to principles of conflicts of laws.

                  SECTION 10.11 Counterparts.  This Indenture may be executed in
any  number  of  counterparts,  each of  which  shall be an  original;  but such
counterparts shall together constitute but one and the same instrument.

                  SECTION  10.12  Effect of  Headings.  The  Article and Section
headings herein and the Table of Contents are for convenience only and shall not
affect the construction hereof.


                                 ARTICLE ELEVEN

                            REDEMPTION OF SECURITIES

                  SECTION 11.1 Right of Optional Redemption;  Prices. The Issuer
at its option may, on and after  October 22,  2002,  redeem all, or from time to
time any part of, the Securities upon payment of the optional  Redemption Prices
set forth in the form of Security  attached as Exhibit A hereto,  together  with
accrued interest to the date fixed for redemption.

                  SECTION 11.2 Notice of Redemption; Partial Redemptions. Notice
of  redemption to the Holders of Securities to be redeemed as a whole or in part
shall be given by mailing notice of such redemption by first-class mail, postage
prepaid,  at least 20 days and not more than 60 days prior to the date fixed for
redemption to such Holders of  Securities at their last  addresses as they shall
appear upon the registry books.  Any notice which is mailed in the manner herein
provided shall be conclusively  presumed to have been duly given, whether or not
the Holder receives the notice. Failure to give notice by mail, or any defect in
the notice to the Holder of any Security designated for redemption as a whole or
in part,  shall not affect the validity of the proceedings for the redemption of
any other Security.

                                      -68-
<PAGE>

                  The notice of redemption to each such Holder shall specify the
principal  amount of each Security held by such Holder to be redeemed,  the date
fixed for redemption (the "Redemption Date"), the CUSIP numbers,  the applicable
Redemption Price, the place or places of payment, that payment will be made upon
presentation and surrender of such Securities, that interest accrued to the date
fixed for  redemption  will be paid as  specified in said notice and that on and
after said date interest  thereon or on the portions thereof to be redeemed will
cease to accrue,  and shall also specify the Conversion Price then in effect and
the date on which the right to convert such  Securities or the portions  thereof
to be redeemed will expire.  In case any Security is to be redeemed in part only
the notice of redemption shall state the portion of the principal amount thereof
to be redeemed and shall state that on and after the date fixed for  redemption,
upon  surrender  of such  Security,  a new Security or  Securities  in principal
amount equal to the unredeemed portion thereof will be issued.

                  The notice of  redemption  of Securities to be redeemed at the
option of the Issuer shall be given by the Issuer or, at the  Issuer's  request,
by the Trustee in the name and at the expense of the Issuer.

                  At  least  one  Business  Day  prior  to the  Redemption  Date
specified in the notice of  redemption  given as provided in this  Section,  the
Issuer will deposit  with the Trustee or with one or more Paying  Agents (or, if
the Issuer is acting as its own Paying Agent,  set aside,  segregate and hold in
trust as  provided  in Section  2.3) an amount of money suffi cient to redeem on
the  Redemption  Date all the  Securities so called for  redemption  (other than
those theretofore  surrendered for conversion pursuant to Article Twelve) at the
appropriate  Redemption  Price,  together with accrued interest to and including
the date  fixed  for  redemption.  If any  Security  called  for  redemption  is
converted  pursuant  hereto,  any money deposited with the Trustee or any Paying
Agent or so segregated and held in trust for the redemption  Order,  or, if then
held by the Issuer,  shall be discharged  from such trust.  If less than all the
outstanding Securi-

                                      -69-
<PAGE>

ties are to be redeemed, the Issuer will deliver to the Trustee at least 10 days
prior to the date of making of the notice of redemption an Officers' Certificate
stating the aggregate principal amount of Securities to be redeemed.

                  If  less  than  all the  Securities  are to be  redeemed,  the
Trustee shall select,  by lot, pro rata or by such other manner as it shall deem
appropriate and fair,  Securities to be redeemed in whole or in part. Securities
may  be  redeemed  in  part  in  multiples  equal  to  the  minimum   authorized
denomination for Securities or any multiple thereof.  The Trustee shall promptly
notify the Issuer in writing of the Securities  selected for redemption  and, in
the case of any Securities selected for partial redemption, the principal amount
thereof to be redeemed.  For all purposes of this Indenture,  unless the context
otherwise  requires,  all  provisions  relating to the  redemption of Securities
shall  relate,  in the case of any Security  redeemed or to be redeemed  only in
part, to the portion of the principal  amount of such Security which has been or
is  to  be  redeemed.  If  any  Security  selected  for  partial  redemption  is
surrendered for conversion after such selection,  the converted  portion of such
Security  shall be  deemed  (so far as may be) to be the  portion  selected  for
redemption. Upon any redemption of less than all the Securities, for purposes of
the  selection  for  redemption,  the  Issuer  and  the  Trustee  may  treat  as
Outstanding  Securities  surrendered for conversion during the period of 15 days
next  preceding  the  mailing of a notice of  redemption,  and need not treat as
Outstanding  any  Security  authenticated  and  delivered  during such period in
exchange for the  unconverted  portion of any Security  converted in part during
such period.

                  SECTION 11.3 Payment of Securities  Called for Redemption.  If
notice  of  redemption  has been  given as above  provided,  the  Securities  or
portions of Securities  specified in such notice shall become due and payable on
the date and at the place  stated in such  notice at the  applicable  Redemption
Price,  together  with  interest  accrued  to and  including  the date fixed for
redemption,  and on and after said date (unless the Issuer shall  default in the
payment of


                                      -70-
<PAGE>

such Securities at the Redemption Price,  together with interest accrued to said
date)  interest  on the  Securities  or  portions  of  Securities  so called for
redemption  shall cease to accrue and such Securities shall cease from and after
the close of business on the  Business Day  immediately  prior to the date fixed
for  redemption to be  convertible  pursuant to the provisions of Article Twelve
or,  except as provided  in Sections  2.4 and 9.4, be entitled to any benefit or
security under this  Indenture,  and the Holders  thereof shall have no right in
respect of such Securities except the right to receive the applicable Redemption
Price  thereof  and  unpaid  interest  to  and  including  the  date  fixed  for
redemption.  On  presentation  and  surrender of such  Securities  at a place of
payment  specified in said notice,  said  Securities or the  specified  portions
thereof  shall be paid and redeemed by the Issuer at the  applicable  Redemption
Price,  together with interest  accrued  thereon to and including the date fixed
for redemption,  provided that any payment of interest  becoming due on or prior
to the date  fixed  for  redemption  shall be  payable  to the  Holders  of such
Securities  registered as such on the relevant  record date subject to the terms
and provisions of Section 2.11 hereof.

                  If any  Security  called for  redemption  shall not be so paid
upon surrender thereof for redemption,  the principal shall,  until paid or duly
provided for,  bear  interest from the date fixed for  redemption at the rate of
interest  specified in such Security and such Security shall remain  convertible
pursuant  to the  provisions  of  Article  Twelve  until the  principal  of such
Security shall have been paid or duly provided for.

                  Upon  presentation of any Security  redeemed in part only, the
Issuer shall execute and the Trustee shall authenticate and deliver to or on the
order of the Holder  thereof,  at the expense of the Issuer,  a new  Security or
Securities,  of  authorized  denominations,  in  principal  amount  equal to the
unredeemed portion of the Security so presented.

                  SECTION 11.4 Exclusion of Certain  Securities from Eligibility
for Selection for Redemption.  Securities shall

                                      -71-
<PAGE>

be excluded from eligibility for selection for redemption if they are identified
by  registration  and  certificate  number in a written  statement  signed by an
Officer of the Issuer and delivered to the Trustee at least 40 days prior to the
last date on which  notice of  redemption  may be given as being owned of record
and beneficially by, and not pledged or hypothecated by either (a) the Issuer or
(b) an entity specifically  identified in such Officers' Certificate directly or
indirectly  controlling  or  controlled  by or under  direct or indirect  common
control with the Issuer.

                  SECTION 11.5 Conversion Arrangement on Call for Redemption. In
connection with any redemption of the Securities, the Issuer may arrange for the
purchase and  conversion  of any  Securities  by an  agreement  with one or more
investment  bankers or other  purchasers  (the  "Purchasers")  to purchase  such
Securities by paying to the Trustee in trust for the Holders, on or before 11:00
a.m., Eastern Standard Time, on the Redemption Date, an amount not less than the
applicable  Redemption  Price,  together with interest accrued and unpaid to the
Redemption  Date, of such Securities.  Notwithstanding  anything to the contrary
contained in this Article,  the  obligation of the Issuer to pay the  Redemption
Price,  together with interest  accrued and unpaid to the Redemption Date, shall
be deemed to be satisfied and discharged to the extent such amount is so paid by
such Purchasers.  If such an agreement is entered into (a copy of which shall be
filed with the Trustee prior to the close of business on the second Business Day
immediately  prior to the Redemption Date), any Securities called for redemption
that are not duly  surrendered for conversion by the Holders thereof may, at the
option of the Issuer,  be deemed,  to the fullest  extent  permitted by law, and
consistent with any agreement or agreements with such Purchasers, to be acquired
by such  Purchasers  from such  Holders  and  (notwithstanding  anything  to the
contrary  contained  in  this  Article)   surrendered  by  such  Purchasers  for
conversion,  all  as of  immediately  prior  to the  close  of  business  on the
Redemption Date (and the right to convert any such Securities  shall be extended
through such time), subject to payment of the above amount as aforesaid.  At the
written direction of the Issuer,  the Trustee shall hold and

                                      -72-
<PAGE>

dispose of any such  amount paid to it by the  Purchasers  to the Holders in the
same  manner  as it  would  monies  deposited  with  it by the  Issuer  for  the
redemption of  Securities.  Without the  Trustee's  prior  written  consent,  no
arrangement  between  the  Issuer  and  such  Purchasers  for the  purchase  and
conversion  of any  Securities  shall  increase or  otherwise  affect any of the
powers,  duties,  responsibilities or obligations of the Trustee as set forth in
this Indenture, and the Issuer agrees to indemnify the Trustee from, and hold it
harmless against, any loss, liability or expense arising out of or in connection
with any such  arrangement  for the purchase and  conversion  of any  Securities
between  the  Issuer  and such  Purchasers,  including  the costs and  expenses,
including  reasonable legal fees,  incurred by the Trustee in the defense of any
claim  or  liability  arising  out of or in  connection  with  the  exercise  or
performance of any of its powers, duties,  responsibilities or obligations under
this Indenture.


                                 ARTICLE TWELVE

                            CONVERSION OF SECURITIES

                  SECTION 12.1 Conversion Privilege.  A Holder of a Security may
convert it into Class A Common Stock of the Issuer at any time prior to maturity
at the  conversion  price  then in  effect,  except  that,  with  respect to any
Security  called for redemption,  such  conversion  right shall terminate at the
close of business on the Business Day immediately preceding the Redemption Date,
Change in Control  Repurchase  Date or Repurchase  Date (unless the Issuer shall
default in making the  redemption or repurchase  payment then due, in which case
the conversion  right shall  terminate on the date such default is cured and, if
applicable,  the  provisions of Section  13.2(d) are  satisfied).  The number of
shares  of Class A Common  Stock  issuable  upon  conversion  of a  Security  is
determined  as  follows:  divide the  principal  amount to be  converted  by the
Conversion  Price in effect on the Date of  Conversion;  round the result to the
nearest 1/100th of a share.

                                      -73-
<PAGE>

                  The initial Conversion Price is stated in the fourth paragraph
of the reverse of the  Securities  and is subject to  adjustment  as provided in
this Article.

                  A Holder may  convert a portion of a Security  equal to $1,000
principal amount or any integral multiple thereof.  Provisions of this Indenture
that apply to  conversion  of all of a Security  also apply to  conversion  of a
portion of it.

                  SECTION 12.2  Exercise of  Conversion  Privilege.  In order to
exercise the  conversion  privilege,  the Holder of any Security to be converted
shall  surrender  such Security to the Issuer at any time during usual  business
hours at its office or agency  maintained  for the  purpose as  provided in this
Indenture,  accompanied by a fully executed written notice, in substantially the
form set forth on the reverse of the Security, that the Holder elects to convert
such Security or a stated portion thereof constituting a multiple of the minimum
authorized  denomination  thereof,  and,  if such  Security is  surrendered  for
conversion  during the period  between  the close of business on any record date
for such  Security and the opening of business on the related  interest  payment
date (unless such Security shall have been called for redemption on a Redemption
Date or Change in Control Repurchase Date within such period or on such interest
payment  date),  accompanied  also by payment of an amount equal to the interest
payable on such interest  payment date on the portion of the principal amount of
the Security being  surrendered  for  conversion.  A Holder of any Security on a
record date for such Security who converts such Security on the related interest
payment  date will  receive  the  interest  payable on such  Security,  and such
converting  Holder  need  not  include  a  payment  for any such  interest  upon
surrender of such Security for conversion. Such notice shall also state the name
or names (with address) in which the certificate or  certificates  for shares of
Class A Common  Stock shall be issued.  Securities  surrendered  for  conversion
shall (if so required by the Issuer or the  Trustee) be duly  endorsed by, or be
accompanied  by  a  written  instrument  or  instruments  of  transfer  in  form
satisfactory  to the Issuer and the Trustee duly  executed by, the Holder or his
attorney duly authorized in writing. As promptly as

                                      -74-
<PAGE>

practicable  after the receipt of such notice and the surrender of such Security
as aforesaid, the Issuer shall, subject to the provisions of Section 12.7, issue
and deliver at such office or agency to such Holder,  or on his written order, a
certificate  or  certificates  for the  number of full  shares of Class A Common
Stock  issuable  on  such  conversion  of  Securities  in  accordance  with  the
provisions  of this Article and cash, as provided in Section 12.3, in respect of
any fraction of a share of Class A Common  Stock  otherwise  issuable  upon such
conversion.  Such conversion  shall be deemed to have been effected  immediately
prior  to the  close  of  business  on the  date  (herein  called  the  "Date of
Conversion")  on which such  notice  shall have been  received by the Issuer and
such  Security  shall  have been  surrendered  as  aforesaid,  and the Person or
Persons in whose name or names any  certificate  or  certificates  for shares of
Class A Common Stock shall be issuable upon such  conversion  shall be deemed to
have  become on the Date of  Conversion  the  holder or holders of record of the
shares represented thereby;  provided,  however,  that any such surrender on any
date  when  the  stock  transfer  books of the  Issuer  shall  be  closed  shall
constitute  the  person or persons  in whose  name or names the  certificate  or
certificates  for such  shares are to be issued as the  recordholder  or holders
thereof for all purposes at the opening of business on the next  succeeding  day
on  which  such  stock  transfer  books  are  open  but  such  conversion  shall
nevertheless  be at the  Conversion  Price in effect at the close of business on
the date when such Security shall have been so  surrendered  with the conversion
notice.  In the case of  conversion  of a  portion,  but  less  than  all,  of a
Security,  the Issuer shall  execute,  and the Trustee  shall  authenticate  and
deliver to the Holder  thereof,  at the  expense of the  Issuer,  a Security  or
Securities in the aggregate  principal amount of the unconverted  portion of the
Security surrendered.  Except as otherwise expressly provided in this Indenture,
no payment or adjustment  shall be made for interest accrued on any Security (or
portion  thereof)  converted or for  dividends or  distributions  on any Class A
Common Stock issued upon conversion of any Security;  provided, however, that in
the case of any Securities  which are converted after the close of business on a
relevant  record date and on or prior to the next  succeeding  interest

                                      -75-
<PAGE>

payment  date,  installments  of interest  which are due and payable on the next
succeeding  interest payment date shall be payable on such interest payment date
notwithstanding such conversion (unless such Security shall have been called for
redemption on a Redemption  Date or Change in Control  Repurchase Date after the
close of  business  on such  record date and prior to the opening of business on
such interest payment date) and such interest (whether or not punctually paid or
duly provided for) shall be paid to the Holder of such Securities  registered as
such at the close of business on the  relevant  record date  according  to their
terms.  The  Issuer's  delivery of the fixed  number of shares of Class A Common
Stock into which the  Securities are  convertible  will be deemed to satisfy the
Issuer's  obligation  to pay the  principal  amount  of the  Securities  and all
accrued interest that has not previously been (or is not  simultaneously  being)
paid.  The Class A Common Stock is treated as issued first in payment of accrued
interest and then in payment of principal.

                  SECTION 12.3 Fractional Shares. Except as pro vided below, the
Issuer will not issue fractional  shares of Class A Common Stock upon conversion
of  Securities.  In  lieu  thereof,  in the  sole  discretion  of the  Board  of
Directors, either (a) such fractional interest will be rounded up to the nearest
full  share,  or (b) an  appropriate  amount will be paid in cash by the Issuer,
unless payment in cash is prohibited by the terms of the Issuer's  indebtedness,
in which case fractional shares may be issued. If the Issuer shall deliver cash,
such cash shall be in the amount of the fair market value (as  determined by the
Board of Directors) of such fractional interest. If more than one Security shall
be surrendered for conversion at one time by the same Holder, the number of full
shares  issuable upon  conversion  thereof shall be computed on the basis of the
aggregate  number  of  Securities,  or  the  specified  portions  thereof  to be
converted, so surrendered.

                  SECTION 12.4  Adjustment of Conversion  Price.  The Conversion
Price shall be subject to adjustment from time to time as follows:

                                      -76-
<PAGE>

                  (a) In case the  Issuer  shall  (1) pay a  dividend  or make a
         distribution on Class A Common Stock in shares of Class A Common Stock,
         (2)  subdivide  its  outstanding  shares of Class A Common Stock into a
         greater number of shares or (3) combine its outstanding shares of Class
         A Common Stock into a smaller number of shares, the Conversion Price in
         effect  immediately  prior to such action shall be adjusted as provided
         below so that the Holder of any  Security  thereafter  surrendered  for
         conversion shall be entitled to receive the number of shares of Class A
         Common Stock which he would have been  entitled to receive  immediately
         following  such action had such  Security  been  converted  immediately
         prior thereto. An adjustment made pursuant to this subsection (a) shall
         become  effective  immedi ately,  except as provided in subsection  (e)
         below,  after the record date in the case of a dividend or distribution
         and shall become effective  immediately after the effective date in the
         case of a subdivision or combination.

                  (b) In case the Issuer shall issue rights, warrants or options
         to all  holders  of Class A Common  Stock  entitling  them for a period
         expiring within 45 days after the record date therefor to subscribe for
         or  purchase  shares of Class A Common  Stock at a price per share less
         than the  current  market  price per share (as  determined  pursuant to
         subsection  (d) below) of the Class A Common  Stock on the record  date
         mentioned  below,  the  Conversion  Price shall be adjusted to a price,
         computed  to the nearest  cent,  so that the same shall equal the price
         determined by multiplying:

                           (1) the Conversion Price in effect  immediately prior
                  to the date of issuance of such rights,  warrants or option by
                  a fraction, of which

                           (2) the  numerator  shall be (A) the number of shares
                  of Class A Common Stock outstanding on the date of issuance of
                  such  rights,  warrants or options  immediately  prior to such
                  issuance,  plus (B) the number of shares  which the  aggregate

                                      -77-
<PAGE>

                  offering  price of the total  number of shares so offered  for
                  subscription or purchase would purchase at such current market
                  price  (determined by multiplying  such total number of shares
                  by the exercise price of such rights,  warrants or options and
                  dividing  the  product  so  obtained  by such  current  market
                  price), and of which

                           (3) the denominator shall be (A) the number of shares
                  of Class A Common Stock outstanding on the date of issuance of
                  such rights,  warrants or options,  immediately  prior to such
                  issuance,  plus (B) the number of additional shares of Class A
                  Common  Stock  which  are  so  offered  for   subscription  or
                  purchase.

                  Such adjustment shall become effective immedi ately, except as
         provided  in  subsection  (e)  below,  after  the  record  date for the
         determination of Holders  entitled to receive such rights,  warrants or
         options.

                  (c) In case the  Issuer  shall  distribute  to all  holders of
         Class A Common  Stock  evidences  of  indebtedness,  equity  securities
         (including  equity interests in the Issuer's  Subsidiaries)  other than
         Class A Common Stock or other assets  (other than cash  dividends),  or
         shall  distribute  to all  holders  of  Class A  Common  Stock  rights,
         warrants  or options  to  subscribe  to  securities  (other  than those
         referred to in subsection (b) above and dividends and  distributions in
         connection  with the  liquidation,  dissolution  or  winding  up of the
         Issuer),  then in each such case the Conversion Price shall be adjusted
         so that the same shall equal the price  determined by  multiplying  the
         Conversion  Price  in  effect  immediately  prior  to the  date of such
         distribution  by a fraction of which the numerator shall be the current
         market price per share (determined as provided in subsection (d) below)
         of the Class A Common Stock on the record date mentioned below less the
         then fair market value (as determined by the Board of Directors,  whose
         determination  shall be conclusive  evidence of such fair market value,
         and

                                      -78-
<PAGE>

         described  in a Board  Resolution  filed with the  Trustee) of the
         portion of the assets,  evidences of indebtedness and equity securities
         so  distributed  or of such  subscription  rights,  warrants or options
         applicable  to one  share  of Class A Common  Stock,  and of which  the
         denominator shall be such current market price per share of the Class A
         Common Stock.  For the purposes of this subsection (c), in the event of
         a  distribution  of shares of capital stock or other  securities of any
         Subsidiary  as a dividend on shares of Class A Common  Stock,  the then
         fair  market  value of the shares of other  securities  so  distributed
         shall be deemed to be the market value  (determined as provided  above)
         of such  shares  or other  securities.  Such  adjustment  shall  become
         effective  immediately,  except as  provided in  subsection  (e) below,
         after the record date for the determination of stockholders entitled to
         receive such distribution.

                  (d) For the purpose of any computation  under  subsections (b)
         and (c) above,  the  current  market  price per share of Class A Common
         Stock on any date  shall be deemed to be the  average  of the Last Sale
         Prices  of a share  of Class A Common  Stock  for the five  consecutive
         Trading  Days  commencing  not more than 20 Trading  Days  before,  and
         ending not later than, the earlier of the date in question and the date
         before  the "ex" date with  respect  to the  issuance  or  distribution
         requiring such  computation.  For purposes of this paragraph,  the term
         "'ex' date",  when used with  respect to any issuance or  distribution,
         means the first date on which the Class A Common Stock  trades  regular
         way on the principal national  securities exchange on which the Class A
         Common  Stock is listed or  admitted to trading (or if not so listed or
         admitted  on NASDAQ or a  similar  organization  if NASDAQ is no longer
         reporting  trading  information)  without  the  right to  receive  such
         issuance or distribution.

                  (e) In any case in which this  Section  shall  require that an
         adjustment be made immediately follow ing a record date, the Issuer may
         elect to defer the

                                      -79-
<PAGE>


         effectiveness  of such  adjustment  (but in no event until a date later
         than the effective  time of the event giving rise to such  adjustment),
         in which case the Issuer shall, with respect to any Security  converted
         after such  record date and before  such  adjustment  shall have become
         effective (i) defer making any cash payment pursuant to Section 12.3 or
         issuing to the Holder of such  Security the number of shares of Class A
         Common Stock and other capital  stock of the Issuer  issuable upon such
         conversion  in excess of the  number of shares of Class A Common  Stock
         and other capital stock of the Issuer  issuable  thereupon  only on the
         basis of the Conversion  Price prior to adjustment,  and (ii) not later
         than five  Business  Days  after  such  adjustment  shall  have  become
         effective,  pay to such Holder the appropriate cash payment pursuant to
         Section 12.3 and issue to such Holder the additional  shares of Class A
         Common  Stock and other  capital  stock of the Issuer  issuable on such
         conversion.

                  (f) No adjustment in the Conversion Price shall be required if
         Securityholders  are to participate  in the  transaction on a basis and
         with  notice  that the  Board of  Directors  determines  to be fair and
         appropri ate in light of the basis and notice on which holders of Class
         A  Common  Stock  participate  in  the  transaction.  In  addition,  no
         adjustment  in the  Conversion  Price  shall be  required  unless  such
         adjustment  would require an increase or decrease of at least 1% in the
         Conversion Price; provided that any adjustments which by reason of this
         subsection (f) are not required to be made shall be carried forward and
         taken into account in any subsequent adjustment. All calculations under
         this  Article  shall  be made  to the  nearest  cent or to the  nearest
         one-hundredth of a share, as the case may be.

                  (g)  Whenever  the  Conversion  Price is  adjusted  as  herein
         provided,  the Issuer shall promptly (i) file with the Trustee and each
         conversion agent an Officers'  Certificate setting forth the Conversion
         Price after such adjustment and setting forth in reasonable  detail the
         facts  requiring  such  adjustment  and the

                                      -80-
<PAGE>

         calculations on which the adjustment is based,  which certificate shall
         be conclusive  evidence of the correctness of such adjustment and which
         shall be made available by the Trustee to the Holders of Securities for
         inspection  thereof,  (ii)  mail or cause to be mailed a notice of such
         adjustment, setting forth the adjusted Conversion Price and the date on
         which such adjustment  became or becomes  effective,  to each Holder of
         Securities at his address as the same appears on the registry  books of
         the Issuer.

                  To the extent  permitted  by law, the Issuer from time to time
may  reduce  the  Conversion  Price by any  amount for any period of at least 20
days, if the Board of Directors  has made a  determination  that such  reduction
would be in the best  interests  of the  Issuer,  which  determination  shall be
conclusive.  In such case, the Issuer shall give at least 15 days' notice of the
reduction. In addition, at its option, the Issuer may make such reduction in the
Conversion  Price as the Board of Directors deems advisable to avoid or diminish
any income tax to holders of Class A Common Stock resulting from any dividend or
distribution  of stock (or rights to acquire stock) or from any event treated as
such for income tax purposes.

                  SECTION 12.5  Continuation of Conversion  Privilege in Case of
Reclassification,  Reorganization,  Change,  Merger,  Consolidation  or  Sale of
Assets.  If any transaction shall occur,  including  without  limitation (i) any
recapitalization  or  reclassification  of shares of Class A Common Stock (other
than a change in par value,  or from par value to no par  value,  or from no par
value to par value,  or as a result of a subdivision or combination of the Class
A Common  Stock),  (ii) any  consolidation  or merger of the Issuer with or into
another  person or any merger of another  person  into the Issuer  (other than a
consolidation or merger that does not result in a reclassification,  conversion,
exchange or cancellation of Class A Common Stock), (iii) any sale or transfer of
all or  substantially  all of the assets of the Issuer,  or (iv) any  compulsory
share  exchange,  pursuant to any of which holders of Class A Common Stock shall
be  entitled  to  receive  other  securities,   cash  or  other  property,  then
appropriate  provision  shall be made so that the Holder of each  Security  then
Outstanding  shall have the right  thereafter to convert such Security only into
the kind and amount of the  securities,  cash or other

                                      -81-
<PAGE>

property   that  would  have  been   receivable   upon  such   recapitalization,
reclassification,  consolidation,  merger, sale, transfer or share exchange by a
holder of the number of shares of Class A Common Stock issuable upon  conversion
of such Security immediately prior to such  recapitalization,  reclassification,
consolidation,  merger, sale, transfer or share exchange, after giving effect to
any adjustment in the conversion  price in accordance with this  Indenture.  The
company  formed by such  consolidation  or  resulting  from such  merger or that
acquires such assets or that acquires the Issuer's  shares,  as the case may be,
shall make provisions in its certificate of incorporation  or other  constituent
document to establish such right.  Such  certificate of  incorporation  or other
constituent  document shall provide for adjustments  that, for events subsequent
to the effective date of such certificate of incorporation or other  constituent
documents,  shall be as nearly  equivalent as may be practicable to the relevant
adjustments provided for in Section 12.4 and in this Section.

                  SECTION 12.6  Notice of Certain Events.  In case:

                  (a)  the  issuer  shall  declare  a  dividend  (or  any  other
         distribution)  payable to the  holders of Class A Common  Stock  (other
         than cash dividends and dividends payable in Class A Common Stock); or

                  (b) the Issuer shall  authorize the granting to the holders of
         Class A Common Stock of rights, warrants or options to subscribe for or
         purchase  any  shares  of stock of any  class or of any  other  rights,
         warrants or options; or

                  (c) the Issuer shall authorize any reclassifica tion or change
         of the Class A Common Stock (other than a subdivision or combination of
         its  outstanding  shares  of  Class A Common  Stock or a change  in par
         value,  or from par value to no par value,  or from no par value to

                                      -82-
<PAGE>

         par  value),  or any  consolidation  or merger to which the Issuer is a
         party and for which  approval  of any stock  holders  of the  Issuer is
         required,  or the sale or  conveyance of all or  substantially  all the
         property or business of the Issuer; or

                  (d) there  shall be  proposed  any  voluntary  or  involuntary
         dissolution, liquidation or winding-up of the Issuer;

then,  the Issuer shall cause to be filed with the  Trustee,  and, if other than
the Corporate  Trust Office of the Trustee,  at the office or agency  maintained
for the purpose of conversion of the  Securities as provided in Section 2.3, and
shall  cause to be mailed to each  Holder of  Securities,  at his  address as it
shall appear on the registry books of the Issuer, as promptly as possible but in
any event at least 20 days before the date hereinafter specified (or the earlier
of the dates  hereinafter  specified,  in the  event  that more than one date is
specified),  a notice  stating  the date on which (1) a record is expected to be
taken for the  purpose  of such  dividend,  distribution,  rights,  warrants  or
options,  or if a record is not to be taken, the date as of which the holders of
Class A Common  Stock of record to be entitled to such  dividend,  distribution,
rights or warrants are to be determined,  or (2) such reclassification,  change,
consolidation,  merger, sale, transfer, conveyance, dissolution,  liquidation or
winding-up is expected to become  effective and the date, if any is to be fixed,
as of which it is expected  that holders of Class A Common Stock of record shall
be entitled to exchange  their shares of Class A Common Stock for  securities or
other property deliverable upon such  reclassification,  change,  consolidation,
merger, sale, transfer, conveyance, dissolution, liquidation or winding-up.

                  SECTION 12.7 Taxes on Conversion. The issuance and delivery of
certificates  for shares of Class A Common  Stock on  conversion  of  Securities
shall be made without  charge to the  converting  Holder of Securities  for such
certificates  or for any  documentary,  stamp or similar issue or transfer taxes
payable to the United States of America or

                                      -83-
<PAGE>

any political subdivision or taxing authority thereof in respect of the issuance
or delivery of such certificates;  provided,  however, that the Issuer shall not
be  required  to pay any tax which may be payable  in  respect  of any  transfer
involved in the issuance of certificates for shares of Class A Common Stock, and
no such issue or delivery  shall be made unless and until the Person  requesting
such issue or delivery  has paid to the Issuer the amount of any such tax or has
established, to the satisfaction of the Issuer, that such tax has been paid.

                  SECTION  12.8  Issuer to  Provide  Class A Common  Stock.  The
Issuer  covenants that it will reserve and keep available,  free from preemptive
rights,  out of its  authorized but unissued  shares,  solely for the purpose of
issue upon  conversion of Securities as herein  provided,  sufficient  shares of
Class A Common Stock to provide for the conversion of the  Securities  from time
to time as such Securities are presented for conversion.

                  If any shares of Class A Common  Stock to be reserved  for the
purpose of conversion  of  Securities  hereunder  require  registration  with or
approval  of any  governmental  authority  under any Federal or State law before
such shares may be validly issued or delivered upon conversion,  then the Issuer
covenants that it will in good faith and as expeditiously  as possible  endeavor
to secure such registration or approval, as the case may be; provided,  however,
that  nothing  in  this  Section  shall  be  deemed  to  affect  in any  way the
obligations  of the Issuer to convert  Securities  into Class A Common  Stock as
provided in this Article.

                  Before  taking  any action  which  would  cause an  adjustment
reducing the Conversion  Price below the then par value,  if any, of the Class A
Common  Stock,  the Issuer  will take all  corporate  action  which may,  in the
Opinion of  Counsel,  be  necessary  in order that the  Issuer may  validly  and
legally  issue fully paid and  non-assessable  shares of Class A Common Stock at
such adjusted Conversion Price.

                                      -84-
<PAGE>

                  The Issuer  covenants  that all shares of Class A Common Stock
which  may be issued  upon  conversion  of  Securities  will upon  issue be duly
authorized,  validly issued and fully paid and  non-assessable by the Issuer and
free of  preemptive  rights  and of any lien or adverse  claim and that,  if the
Class A Common  Stock is then  listed on any  national  securities  exchange  or
quoted on NASDAQ,  the shares of Class A Common  Stock  which may be issued upon
conversion of Securities will be similarly  listed or quoted at the time of such
issuance.

                  The Issuer  covenants  that,  upon conversion of Securities as
herein provided, there will be credited to Class A Common Stock par capital from
the  consideration  for which the shares of Class A Common Stock  issuable  upon
such conversion are issued an amount per share of Class A Common Stock so issued
as determined by the Board of Directors, which amount shall not be less than the
amount  required by law and by the Issuer's  certificate  of  incorporation,  as
amended,  as in effect on the date of such conversion.  For the purposes of this
covenant the net  proceeds  received by the Issuer from the issuance and sale of
the Securities  converted,  less any cash conversion,  shall be deemed to be the
amount of  consideration  for which the shares of Class A Common Stock  issuable
upon such conversion are issued.

                  SECTION 12.9 Disclaimer of Responsibility for Certain Matters.
Neither the Trustee nor any  Conversion  Agent or agent of the Trustee  shall at
any time be under any duty or  responsibility  to any  Holder of  Securities  to
determine  whether  any facts exist  which may  require  any  adjustment  of the
Conversion  Price, or with respect to the Officers'  Certificate  referred to in
Section 12.4(g),  or with respect to the nature or extent of any such adjustment
when  made,  or  with  respect  to the  method  employed,  or  herein  or in any
supplemental  indenture provided to be employed, in making the same. Neither the
Trustee  nor any  Conversion  Agent  nor  any  agent  of the  Trustee  shall  be
accountable with respect to the validity,  registration,  listing,  or value (or
the kind or amount) of any shares of Class A Common Stock,  or of any securities
or cash or other property, which may at any time be issued or delivered upon the
conversion of any

                                      -85-
<PAGE>

Security;  and  neither  the  Trustee  nor  any  agent  of the  Trustee  nor any
Conversion  Agent makes any  representation  with respect  thereto.  Neither the
Trustee  nor any  Conversion  Agent  nor  any  agent  of the  Trustee  shall  be
responsible  for any failure of the Issuer to make any cash payment or to issue,
register  the transfer of or deliver any shares of Class A Common Stock or stock
certificates or other  securities or property upon the surrender of any Security
for the purpose of  conversion  or,  subject to Sections  5.1 and 5.2, to comply
with any of the covenants of the Issuer contained in this Article.

                  SECTION  12.10 Return of Funds  Deposited  for  Redemption  of
Converted  Securities.  Any funds which at any time shall have been deposited by
the Issuer or on its behalf with the Trustee or any other  Paying  Agent for the
purpose of paying the  principal  of and interest on any of the  Securities  and
which shall not be required for such purposes  because of the conversion of such
Securities,  as provided in this Article, shall after such conversion,  upon the
written  request of the  Issuer,  be repaid to the Issuer by the Trustee or such
other Paying Agent.


                                ARTICLE THIRTEEN

               RIGHT TO REQUIRE REDEMPTION UPON CHANGE IN CONTROL

                  SECTION 13.1 Right to Require Redemption. If at any time there
shall occur any Change in Control (as  defined  below) of the Issuer,  then each
Holder shall have the right, at such Holder's  option,  to require the Issuer to
redeem,  and upon the exercise of such right the Issuer shall redeem, all or any
part of such  Holder's  Securities  that is  $1,000 in  principal  amount or any
integral multiple thereof, on the date (the "Change in Control Repurchase Date")
that is 45 days after the date of the  Issuer  Notice  (as  defined  below) at a
price in cash equal to the  principal  amount  thereof,  and  accrued and unpaid
interest to the Repurchase Date (the "Change in Control Repurchase Price").

                                      -86-
<PAGE>

                  SECTION 13.2 Notices;  Method of Exercising  Redemption Right,
etc. (a) Unless the Issuer shall have theretofore  called for redemption all the
Securities then  Outstanding  pursuant to Article Eleven,  on or before the 30th
day after the  occurrence of a Change in Control,  the Issuer or, at the request
of the  Issuer,  the  Trustee,  shall  forward  to all  holders of record of the
Securities a notice (the  "Issuer  Notice") of the  occurrence  of the Change in
Control and of the redemption right set forth herein arising as a result thereof
in the manner  provided in Section 10.4 hereof.  The Issuer shall also deliver a
copy of the Issuer Notice to the Trustee prior to or promptly  after the mailing
of such Issuer Notice.

                  Each Issuer Notice shall state:

                  (1) the Change in Control Repurchase Date;

                  (2) the date by which the  Securities  with  respect  to which
         such  right is  being  exercised  and the  irrevocable  written  notice
         referred to in Section 13.2(b) must be delivered to the Trustee;

                  (3) the  Change in Control  Repurchase  Price,  including  and
         accrued interest, if any;

                  (4) a description of the procedure  which a Holder must follow
         to exercise a  redemption  right  including  a form of the  irrevocable
         written notice referred to in Section 13.2(b); and

                  (5) the Conversion Price then in effect, the date on which the
         right to convert the principal  amount of the Securities to be redeemed
         will  terminate  and the place or places where such  Securities  may be
         surrendered for conversion.

                  No  failure  of the  Issuer to give the  Issuer  Notice or any
defect therein shall limit any Holder's right to exercise a redemption  right or
affect the validity of the proceedings for the redemption of Securities.

                                      -87-
<PAGE>

                  (b) To exercise a redemption  right, a Holder shall deliver to
the  Trustee on or before  the 30th day after the date of the Issuer  Notice (i)
irrevocable  written notice of the Holder's exercise of such right, which notice
shall set forth  the name of the  Holder,  the  amount of the  Securities  to be
redeemed (which shall be in any authorized  denomination),  and a statement that
an election to exercise the redemption right is being made thereby, and (ii) the
Securities with respect to which the redemption right is being  exercised,  duly
endorsed for transfer to the Issuer.  Securities held by a securities depositary
may be  delivered  in such other  manner as may be agreed to by such  securities
depositary and the Issuer. Such written notice shall be irrevocable.  Subject to
the provisions of subsection (d) below,  Securities  surrendered  for redemption
together with such irrevocable written notice shall cease to be convertible from
the date of delivery of such notice.  If the Change in Control  Repurchase  Date
falls after the record date and before the following  interest payment date, any
Securities to be redeemed must be  accompanied  by payment of an amount equal to
the interest  thereon which the registered  Holder thereof is to receive on such
interest  payment date,  and,  notwithstanding  such  redemption,  such interest
payment  will be made by the  Issuer to the  registered  Holder  thereof  on the
applicable record date.

                  (c) In the event a  redemption  right  shall be  exercised  in
accordance  with the terms hereof,  the Issuer shall pay or cause to be paid the
Change in  Control  Repurchase  Price in cash,  to the  Holder on the  Change in
Control  Repurchase  Date.  The principal of and accrued  interest on Securities
payable  at the  Change in  Control  Repurchase  Price on the  Change in Control
Repurchase  Date  shall  be  considered  to be  principal  due on such  date for
purposes of this Indenture, including Article Four.

                  (d) If any Security surrendered for redemption shall not be so
redeemed  on the Change in  Control  Repurchase  Date,  such  Security  shall be
convertible  at any time  from the  Change  in  Control  Repurchase  Date  until
redeemed and, until redeemed,  continue to bear interest to the extent permitted
by applicable law from the Change in Control

                                      -88-
<PAGE>

Repurchase Date at the same rate borne by such Security. The Issuer shall pay to
the Holder of such  Security the  additional  amount  arising as a result of the
provisions  of this Section  13.2(d) at the same time that it pays the Change in
Control   Repurchase  Price,  and  if  applicable  such  Security  shall  remain
convertible  into Class A Common  Stock  until the Change in Control  Repurchase
Price plus any additional amounts owing on such Security shall have been paid or
duly provided for.

                  (e) Any Security which is to be redeemed only in part shall be
surrendered  at any office or agency of the Issuer  designated  for that purpose
pursuant to Section 2.3 (with,  if the Issuer or the  Trustee so  requires,  due
endorsement by, or a written  instrument of transfer in form satisfactory to the
Issuer and the Trustee duly executed by, the Holder thereof or his attorney duly
authorized  in writing),  and the Issuer shall  execute,  and the Trustee  shall
authenticate  and deliver to the Holder of such Security without service charge,
a new Security or  Securities,  of any authorized  denomination  as requested by
such  Holder,  in  aggregate  principal  amount equal to and in exchange for the
unredeemed portion of the Security so surrendered.

                  SECTION  13.3  Definition  of Change in Control.  A "Change in
Control" is deemed to have  occurred when (i) any person or group other than one
or more of the Principal  Stockholders  (as  hereinafter  defined) or any person
employed by the Issuer in a management capacity as of September 28, 1999 (or any
group of which  any of them is a member,  collectively,  a  "Permitted  Owner"),
acquires  beneficial  ownership of,  directly or  indirectly,  shares of capital
stock of the Issuer  sufficient to entitle such person to exercise more than 50%
of the total  voting power of all classes of capital  stock  entitled to vote in
elections  of  directors  (whether by means of an exchange  offer,  liquidation,
tender   offer,   consolidation,    merger,    combination,    reclassification,
recapitalization or otherwise),  or (ii) the Issuer sells, leases,  exchanges or
transfers  (in one  transaction  or a series  of  related  transactions)  all or
substantially all of its assets to any

                                      -89-
<PAGE>

person or group (in each  instance,  as the term  "person" or "group" is used in
Section  13(d)(3)  or  14(d)(2)  of the  Securities  Exchange  Act of  1934,  as
amended), other than one or more Permitted Owners, provided that any transaction
described  in (i) or (ii)  (whether  or not in any such case to or  involving  a
Permitted Owner) that results in the Class A Common Stock (or a successor common
equity security into which the Securities become convertible pursuant to Section
12.4) no longer  being  listed on a national  securities  exchange  or traded on
NASDAQ shall also be  considered a Change in Control.  "Principal  Stockholders"
means Steven B. Dodge, Thomas H. Stoner, Hicks, Muse, Tate & Furst Incorporated,
Cox Telecom  Towers,  Inc.  and Clear  Channel  Communications,  Inc.  and their
Affiliates.

                  SECTION  13.4  Limitation  on  Right  to  Require  Redemption.
Notwithstanding  anything herein to the contrary, no Holder shall have any right
to require redemption pursuant to this Article if either (i) the Last Sale Price
(or if on any such  Trading  Day the Class A Common  Stock is not  quoted by any
organization referred to in the definition of Last Sale Price, the fair value of
the Class A Common Stock on such day, as conclusively determined by the Board of
Directors) on any five Trading Days during the 10 Trading Day period immediately
preceding  the date of the Change in Control  shall  equal or exceed 105% of the
Conversion  Price in effect on such  Trading  Days or (ii) with  respect  to any
transaction  described  in  clause  (i) of  Section  13.3,  or  any  transaction
described  in  clause  (ii) of  Section  13.3  (so long as such  transaction  is
accompanied  by  or  immediately   followed  by  the  complete  liquidation  and
dissolution  of the Issuer),  all the  consideration  to be paid for the Class A
Common  Stock  or the  assets,  as the  case  may  be,  in  the  transaction  or
transactions constituting the Change in Control (A) has an aggregate fair market
value of at least 105% of the  Conversion  Price with  respect to such  Holder's
Securities in effect  immediately  prior to the closing of such  transaction and
(B) consists of cash,  securities  traded on a national  securities  exchange or
quoted on NASDAQ or a combination of cash and securities.


                                      -90-
<PAGE>

                                ARTICLE FOURTEEN

                REPURCHASE OF SECURITIES AT OPTION OF THE HOLDER

                  SECTION  14.1  General.  Securities  shall be purchased by the
Issuer as of October 22, 2006 (the "Repurchase  Date"),  at the repurchase price
(the "Repurchase Price") set forth in the form of Security attached as Exhibit A
hereto, at the option of the Holder thereof, upon:

                  (1) delivery to the Paying  Agent,  by the Holder of a written
         notice  of  purchase  (the  "Repurchase  Notice")  at any time from the
         opening of business  on the date that is 20 Business  Days prior to the
         Repurchase  Date until the close of  business  on the  Repurchase  Date
         stating:

                           (A) the certificate  number of the Security which the
                  Holder will deliver to be purchased,

                           (B)  the  portion  of  the  principal  amount  of the
                  Security which the Holder will deliver to be purchased,  which
                  portion must be $1,000 or an integral multiple thereof,

                           (C) that such  Security  shall be purchased as of the
                  Repurchase Date pursuant to the terms and conditions specified
                  in the Securities and in this Indenture, and

                           (D) in the  event  the  Issuer  elects,  pursuant  to
                  Section  14.2,  to pay the  Repurchase  Price,  in whole or in
                  part,  in shares of Class A Common  Stock but such  portion of
                  the  Repurchase  Price  shall  ultimately  be  payable to such
                  Holder  entirely  in cash  because  any of the  conditions  to
                  payment of the Repurchase Price in Class A Common Stock is not
                  satisfied  prior to the close of  business  on the  Repurchase
                  Date, as set forth in Section 14.4, whether such Holder elects
                  (i) to withdraw  such  Repurchase  Notice as to some or all of
                  the  Securities  to  which  such  Repurchase   Notice

                                      -91-
<PAGE>

                  relates (stating the principal amount and certificate  numbers
                  of the Securities as to which such  withdrawal  shall relate),
                  or (ii) to receive  cash in  respect of the entire  Repurchase
                  Price for all Securities  (or portions  thereof) to which such
                  Repurchase Notice relates; and

                  (2) delivery of such Security to the Paying Agent prior to, on
         or after the Repurchase Date (together with all necessary endorsements)
         at the offices of the Paying Agent,  such delivery being a condition to
         receipt  by the  Holder of the  Repurchase  Price  therefor;  provided,
         however,  that the  Repurchase  Price shall be so paid pursuant to this
         Article only if the Security so delivered to the Trustee  shall conform
         in all respects to the  description  thereof in the related  Repurchase
         Notice.

                  If a Holder,  in such  Holder's  Repurchase  Notice and in any
written notice of withdrawal  delivered by such Holder  pursuant to the terms of
Section  14.9,  fails to  indicate  such  Holder's  choice  with  respect to the
election set forth in clause (D) of Section 14.1(1), such Holder shall be deemed
to have  elected to receive  cash in  respect  of the  Repurchase  Price for all
Securities  subject to such Repurchase  Notice in the circumstances set forth in
such clause (D).

                  The Issuer shall purchase from the Holder thereof, pursuant to
this Article, a portion of a Security if the principal amount of such portion is
$1,000 or an integral  multiple of $1,000.  Provisions  of this  Indenture  that
apply to the  purchase of all of a Security  also apply to the  purchase of such
portion of such Security.

                  Any  purchase  by  the  Issuer  contemplated  pursuant  to the
provisions  of  this  Article  shall  be  consummated  by  the  delivery  of the
consideration  to be received by the Holder promptly  following the later of the
Repurchase Date and the time of delivery of the Security.

                                      -92-
<PAGE>

                  Notwithstanding  anything  herein to the contrary,  any Holder
delivering to the Paying Agent a Repurchase Notice  contemplated by this Section
14.1 shall have the right to withdraw such  Repurchase  Notice at any time prior
to the close of business on the Repurchase  Date by delivery of a written notice
of withdrawal to the Paying Agent in accordance with Section 14.9.

                  The  Paying  Agent  shall  promptly  notify  the Issuer of the
receipt by it of any Repurchase Notice or written notice of withdrawal thereof.

                  SECTION  14.2  Issuer's  Right to Elect  Manner of  Payment of
Repurchase Price. The Securities to be purchased pursuant to Section 14.1 may be
paid for, at the election of the Issuer,  in cash or Class A Common Stock, or in
any combination of cash and Class A Common Stock,  subject to the conditions set
forth in  Sections  14.3 and 14.4.  The Issuer  shall  designate,  in the Issuer
Repurchase  Notice delivered  pursuant to Section 14.5,  whether the Issuer will
purchase the Securities for cash or Class A Common Stock, or, if a


combination  thereof,  the percentages of the Repurchase  Price of Securities in
respect of which it will pay in cash or Class A Common Stock;  provided that the
Issuer will pay cash for  fractional  interests  in Class A Common  Stock unless
payment in cash is  prohibited  by the terms of the  Issuer's  indebtedness,  in
which case  fractional  shares may be issued.  For purposes of  determining  the
existence of potential fractional interests,  all Securities subject to purchase
by the Issuer held by a Holder shall be considered  together (no matter how many
separate  certificates  are to be presented).  Each Holder whose  Securities are
purchased  pursuant to this Article shall receive the same percentage of cash or
Class A Common  Stock in payment of the  Repurchase  Price for such  Securities,
except (i) as  provided  in Section  14.4 with  regard to the payment of cash in
lieu of fractional shares of Class A Common Stock and (ii) in the event that the
Issuer is unable to purchase the  Securities  of a Holder or Holders for Class A
Common Stock because any necessary  qualifications or registrations of the Class
A Common Stock under applicable  state  securities laws cannot be obtained,  the
Issuer may  purchase  the  Securities  of such Holder or

                                      -93-
<PAGE>

Holders for cash.  The Issuer may not change its  election  with  respect to the
consideration  (or components or  percentages of components  thereof) to be paid
once the Issuer has given its Issuer Repurchase Notice to Securityholders except
pursuant to this  Section  14.2 or  pursuant  to Section  14.4 in the event of a
failure to satisfy,  prior to the close of business on the Repurchase  Date, any
condition to the payment of the Repurchase  Price, in whole or in part, in Class
A Common Stock.

                  At least  three  Business  Days  before the Issuer  Repurchase
Notice Date,  the Issuer shall deliver an Officers'  Certificate  to the Trustee
specifying:

                  (1) the manner of payment selected by the Issuer,

                  (2) the information required by Section 14.5,

                  (3) if the Issuer  elects to pay the  Repurchase  Price,  or a
         specified  percentage  thereof,  in  Class A  Common  Stock,  that  the
         conditions  to such  manner of payment  set forth in Section  14.4 have
         been or will be complied with, and

                  (4) whether the Issuer  desires the Trustee to give the Issuer
         Repurchase Notice required by Section 14.5.

                  SECTION 14.3 Repurchase with Cash. On the Repurchase  Date, at
the option of the Issuer, the Repurchase Price of Securities in respect of which
a  Repurchase  Notice  pursuant to Section  14.1 has been given,  or a specified
percentage  thereof,  may be paid by the Issuer with cash equal to the aggregate
Repurchase Price of such Securities. If the Issuer elects to purchase Securities
with cash, the Issuer  Repurchase  Notice, as provided in Section 14.5, shall be
sent to Holders (and the  Depositary  shall  distribute to beneficial  owners as
required  by  applicable  law)  not  less  than 20  Business  Days  prior to the
Repurchase Date (the "Issuer Repurchase Notice Date").

                  SECTION 14.4 Payment by Issuance of Class A Common  Stock.  On
the  Repurchase  Date,  at the option of the

                                      -94-
<PAGE>

Issuer,  the  Repurchase  Price of  Securities  in respect of which a Repurchase
Notice  pursuant  to Section  14.1 has been  given,  or a  specified  percentage
thereof,  may be paid by the  Issuer  by the  issuance  of a number of shares of
Class A Common Stock equal to the  quotient  obtained by dividing (i) the amount
of cash to which the  Securityholders  would have been  entitled  had the Issuer
elected  to pay all or such  specified  percentage,  as the case may be,  of the
Repurchase  Price of such Securities in cash by (ii) the Market Price of a share
of Class A Common Stock, subject to the next succeeding paragraph.

                  The Issuer will not issue a fractional share of Class A Common
Stock in payment of the Repurchase  Price.  Instead the Issuer will pay cash for
the current market value of the fractional  share. The current market value of a
fraction of a share shall be determined by multiplying  the Market Price by such
fraction and rounding the product to the nearest  whole cent.  It is  understood
that if a Holder elects to have more than one Security purchased,  the number of
shares  of Class A Common  Stock  shall be  based  on the  aggregate  amount  of
Securities to be purchased.

                  If  the  Issuer  elects  to  purchase  the  Securities  by the
issuance of shares of Class A Common Stock,  the Issuer  Repurchase  Notice,  as
provided in Section 14.5, shall be sent to the Holders (and the Depositary shall
distribute  to beneficial  owners as required by applicable  law) not later than
the Issuer Repurchase Notice Date.

                  The  Issuer's  right to exercise  its election to purchase the
Securities  pursuant to this  Article  through the issuance of shares of Class A
Common Stock shall be conditioned upon:

                  (1) the Issuer's not having given its Issuer Repurchase Notice
         of an election to pay  entirely in cash and its giving a timely  Issuer
         Repurchase Notice of election to purchase all or a specified percentage
         of the Securities with Class A Common Stock as provided herein;

                                      -95-
<PAGE>

                  (2) the  registration of the shares of Class A Common Stock to
         be issued in respect of the payment of the  Repurchase  Price under the
         Securities Act or the Exchange Act, in each case, if required;

                  (3)  any  necessary   qualification   or  registration   under
         applicable  state  securities laws or the  availability of an exemption
         from such qualification and registration; and

                  (4) the receipt by the Trustee of an Officers' Certificate and
         an Opinion of Counsel  each  stating that (A) the terms of the issuance
         of the Class A Common Stock are in conformity  with this  Indenture and
         (B) the  shares of Class A Common  Stock to be issued by the  Issuer in
         payment of the Repurchase Price in respect of Securities have been duly
         authorized and, when issued and delivered pursuant to the terms of this
         Indenture  in  payment  of  the  Repurchase  Price  in  respect  of the
         Securities,  will be validly issued, fully paid and non-assessable and,
         to the best of such counsel's  knowledge,  free from preemptive rights,
         and, in the case of such Officers' Certificate, stating that conditions
         (1), (2) and (3) above and the information  publication requirement set
         forth in the second sentence of the next succeeding paragraph have been
         satisfied  and, in the case of such  Opinion of Counsel,  stating  that
         conditions (2) and (3) above have been satisfied.

                  Such Officers'  Certificate shall also set forth the number of
         shares of Class A Common  Stock to be issued for each $1,000  principal
         amount  of  Securities  and the Last  Sale  Price of a share of Class A
         Common  Stock on each Trading Day during the period  commencing  on the
         first  Trading  Day of the  period  during  which the  Market  Price is
         calculated and ending on the Repurchase

         Date. The Issuer may pay the Repurchase  Price (or any portion thereof)
         in Class A Common Stock only if the information  necessary to calculate
         the  Market  Price  is  published  in a  daily  newspaper  of  national
         circulation. If the foregoing conditions are not satisfied with

                                      -96-
<PAGE>

         respect to a Holder or Holders  prior to the close of  business  on the
         Repurchase  Date and the Issuer has elected to purchase the  Securities
         pursuant  to this  Article  through  the  issuance of shares of Class A
         Common Stock,  the Issuer shall pay the entire  Repurchase Price of the
         Securities of such Holder or Holders in cash.

                  The "Market  Price"  means the average of the Last Sale Prices
         of the Class A Common Stock for the five  Trading Day period  ending on
         (if the third  Business Day prior to the  Repurchase  Date is a Trading
         Day,  or if not,  then on the last  Trading  Day  prior  to) the  third
         Business Day prior to the Repurchase  Date,  appropriately  adjusted to
         take into account the occurrence,  during the period  commencing on the
         first of such  Trading  Days  during  such five  Trading Day period and
         ending on the  Repurchase  Date,  of any event  described  in  Sections
         12.4(a),  12.4(b) or 12.4(c),  subject,  however, to the conditions set
         forth in Section 12.4(f).

                  SECTION  14.5  Notice  of  Election.  The  Issuer's  notice of
election  to  purchase  with  cash or  Class A Common  Stock or any  combination
thereof  shall be sent to the Holders (and to  beneficial  owners as required by
applicable  law) in the manner provided in Section 10.4 at the time specified in
Section 14.3 or 14.4,  as  applicable  (the "Issuer  Repurchase  Notice").  Such
Issuer  Repurchase  Notice  shall state the manner of payment  elected and shall
contain the following information:

                  In the event the  Issuer  has  elected  to pay the  Repurchase
         Price (or a specified  percentage  thereof)  with Class A Common Stock,
         the Issuer Repurchase Notice
         shall:

                           (1)  state  that each  Holder  will  receive  Class A
                  Common Stock with a Market Price  determined as of a specified
                  date  prior to the  Repurchase  Date  equal to such  specified
                  percentage of the Repurchase  Price of the Securities  held by
                  such


                                      -97-
<PAGE>


                  Holder  (except  any  cash  amount  to  be  paid  in  lieu  of
                  fractional shares);

                           (2) set forth the  method of  calculating  the Market
                  Price of the Class A Common Stock as required by Section 14.4;
                  and

                           (3) state that,  because the Market  Price of Class A
                  Common Stock will be determined  prior to the Repurchase Date,
                  Holders will bear the market risk with respect to the value of
                  the  Class A Common  Stock to be  received  from the date such
                  Market Price is determined to the Repurchase Date.

                  In any case,  each Issuer  Repurchase  Notice shall  include a
         form of Repurchase Notice to be completed by a Securityholder and shall
         state:

                           (A) the Repurchase Price and the Conversion Price;

                           (B) the name and address of the Paying  Agent and the
                  Conversion Agent;

                           (C) that  Securities as to which a Repurchase  Notice
                  has been given may be  converted  pursuant  to Article  Twelve
                  only if the applicable Repurchase Notice has been withdrawn in
                  accordance with the terms of this Indenture;

                           (D) that Securities must be surrendered to the Paying
                  Agent to collect payment;

                           (E) that the Repurchase  Price for any security as to
                  which a  Repurchase  Notice has been  given and not  withdrawn
                  will be paid promptly  following  the later of the  Repurchase
                  Date and the time of surrender  of such  Security as described
                  in (D) above;

                                      -98-
<PAGE>

                           (F) the procedures the Holder must follow to exercise
                  rights  under this  Article and a brief  description  of those
                  rights;

                           (G) briefly, the conversion rights of the Securities;
                  and

                           (H)  the  procedures  for  withdrawing  a  Repurchase
                  Notice  (including,  without  limitation,  for  a  conditional
                  withdrawal  pursuant  to the terms of  Section  14.1(1)(D)  or
                  Section 14.9).

                  At the Issuer's  request,  the Trustee  shall give such Issuer
Repurchase  Notice in the Issuer's name and at the Issuer's  expense;  provided,
however,  that, in all cases, the text of such Issuer Repurchase Notice shall be
prepared by the Issuer.

                  Upon  determination  of the actual number of shares of Class A
Common Stock to be issued for each $1,000  principal  amount of Securities,  the
Issuer will publish such determination in a newspaper of national circulation.

                  SECTION 14.6  Covenants  of the Issuer.  All shares of Class A
Common Stock  delivered  upon purchase of the  Securities  shall be newly issued
shares or treasury shares, shall be duly authorized,  validly issued, fully paid
and  non-assessable  by the Issuer and shall be free of preemptive rights of any
lien or adverse claim.

                  If the Class A Common  Stock is then  listed  on any  national
securities  exchange or quoted on NASDAQ,  the shares of Class A Common Stock to
be issued to purchase  Securities will be similarly listed or quoted at the time
of such issuance.

                  SECTION  14.7  Procedure  upon  Repurchase.  The Issuer  shall
deposit cash (in respect of a cash purchase under Section 14.3 or for fractional
interests,  as applicable)  or shares of Class A Common Stock,  or a combination
thereof,  as  applicable,  at the time and in the manner as  provided in Section
14.10,  sufficient to pay the

                                      -99-
<PAGE>

aggregate  Repurchase  Price of all Securities to be purchased on the Repurchase
Date pursuant to this Article. As soon as practicable after the Repurchase Date,
the Issuer shall deliver to each Holder entitled to receive Class A Common Stock
through the Paying Agent a certificate  for the number of full shares of Class A
Common Stock issuable in payment of the Repurchase Price and cash in lieu of any
fractional  interests.  The  Person in whose  name the  certificate  for Class A
Common Stock is  registered  shall be treated as a holder of record of shares of
Class A Common Stock on the Business Day following the Repurchase Date.  Subject
to Section  14.4,  no payment or  adjustment  will be made for  dividends on the
Class A Common  Stock  the  record  date for which  occurred  on or prior to the
Repurchase Date.

                  SECTION 14.8 Taxes. If a Holder of a Security is paid in Class
A Common Stock, the Issuer shall pay any documentary,  stamp or similar issue or
transfer  taxes  payable  to the  United  Sates  of  America  or  any  political
subdivision or taxing  authority  thereof in respect of the issuance or delivery
of such Class A Common Stock;  provided,  however,  that the Issuer shall not be
required to pay any tax which may be payable in respect of any transfer involved
in the issuance of shares of Class A Common Stock, and no such issue or delivery
shall be made unless and until the Person  requesting such issue or delivery has
paid to the  Issuer  or the  Paying  Agent  the  amount  of any  such tax or has
established,  to the  satisfaction of the Issuer or the Paying Agent,  that such
tax has been paid.  Nothing  herein shall  preclude  any income tax  withholding
required by law or regulations.

                  SECTION 14.9 Effect of Repurchase Notice.  Upon receipt by the
Paying Agent of the Repurchase  Notice, the Holder of the Security in respect of
which such Repurchase  Notice was given shall (unless such Repurchase  Notice is
withdrawn as specified in the following two  paragraphs)  thereafter be entitled
to  receive  solely the  Repurchase  Price with  respect to such  Security.  The
Repurchase  Price  shall be paid to such  Holder,  subject  to  receipt of funds
and/or securities by the Paying Agent,  promptly  following the later of (x) the
Repurchase Date with respect to such

                                     -100-
<PAGE>

Security  (provided the conditions in Section 14.1 have been  satisfied) and (y)
the time of delivery of such Security to the Paying Agent by the Holder  thereof
in the  manner  required  by  Section  14.1.  Securities  in  respect of which a
Repurchase  Notice  has been given by the Holder  thereof  may not be  converted
pursuant  to  Article  Twelve  on or  after  the  date of the  delivery  of such
Repurchase Notice unless such Repurchase Notice has first been validly withdrawn
as  specified in the  following  two  paragraphs.  The  principal of  Securities
payable as the Repurchase Price on the Repurchase Date shall be considered to be
principal  due on such date for purposes of this  Indenture,  including  Article
Four.

                  A  Repurchase  Notice may be  withdrawn  by means of a written
notice of  withdrawal  delivered to the office of the Paying Agent in accordance
with the  Repurchase  Notice at any time prior to the close of  business  on the
Repurchase Date specifying:

                  (1) the certificate number of the Security in respect of which
         such notice of withdrawal is being submitted;

                  (2) the principal amount of the Security with respect to which
         such notice of withdrawal is being submitted; and

                  (3) the  principal  amount,  if any,  of such  Security  which
         remains subject to the original Repurchase Notice and which has been or
         will be delivered for purchase by the Issuer.

                  A written  notice of withdrawal of a Repurchase  Notice may be
in the form set forth in the preceding  paragraph or may be in the form of (i) a
conditional withdrawal contained in a Repurchase Notice pursuant to the terms of
Section 14.1(1)(D) or (ii) a conditional  withdrawal  containing the information
set forth in Section  14.1(1)(D) and the preceding  paragraph and contained in a
written  notice of withdrawal  delivered to the Paying Agent as set forth in the
preceding paragraph.

                                     -101-
<PAGE>

                  There shall be no purchase of any Securities  pursuant to this
Article  (other than  through the issuance of Class A Common Stock in payment of
the Repurchase Price,  including cash in lieu of fractional shares) if there has
occurred (prior to, on or after, as the case may be, the giving,  by the Holders
of such  Securities,  of the required  Repurchase  Notice) and is  continuing an
Event of Default  (other than a default in the payment of the  Repurchase  Price
with respect to such  Securities).  The Paying Agent will promptly return to the
respective Holders thereof any Securities (x) with respect to which a Repurchase
Notice has been withdrawn in compliance with this  Indenture,  or (y) held by it
during  the  continuance  of an Event of  Default  (other  than a default in the
payment of the Repurchase  Price with respect to such Securities) in which case,
upon such return,  the Repurchase Notice with respect thereto shall be deemed to
have been withdrawn.

                  SECTION 14.10 Deposit of Repurchase Price. Prior to 11:00 a.m.
(New York City time) on the  Repurchase  Date the Issuer shall  deposit with the
Trustee or with one or more  Paying  Agents  (or, if the Issuer is acting as its
own Paying Agent,  shall segregate and hold in trust as provided in Section 2.3)
an amount of money (in immediately available funds if deposited on such Business
Day) or Class A Common  Stock,  if permitted  hereunder,  sufficient  to pay the
aggregate Repurchase Price of all of the Securities or portions thereof that are
to be purchased as of the Repurchase Date.

                  SECTION 14.11  Securities  Repurchased  in Part.  Any Security
which is to be purchased  only in part shall be surrendered at the office of the
Paying Agent (with,  if the Issuer or the Trustee so requires,  due  endorsement
by, or a written  instrument of transfer in form  satisfactory  to the Issuer or
the Trustee duly executed by, the Holder thereof or such Holder's  attorney duly
authorized  in writing)  and the Issuer  shall  execute  and the  Trustee  shall
authenticate and deliver to the Holder of such Security, without service charge,
a new Security or  Securities,  of any authorized  denomination  as requested by
such Holder in aggregate  principal  amount  equal to, and in exchange  for, the
portion

                                     -102-
<PAGE>

of the principal amount of the Security so surrendered which is not purchased.

                  SECTION  14.12  Issuer to  Comply  with  Securities  Laws Upon
Purchase of Securities.  In connection with any offer to purchase or purchase of
Securities under this Article (provided that such offer or purchase  constitutes
an "issuer tender offer" for purposes of Rule 13e-4 (which term, as used herein,
includes any successor  provision thereto) under the Exchange Act at the time of
such offer or  purchase),  the Issuer  shall (i) comply with Rule 13e-4 and Rule
14e-1  under the  Exchange  Act,  (ii) file the related  Schedule  13E-4 (or any
successor schedule,  form or report) under the Exchange Act, and (iii) otherwise
comply with all Federal and state securities laws so as to permit the rights and
obligations  under this  Article to be  exercised  in the time and in the manner
specified in this Article.

                  SECTION  14.13  Repayment  to the Issuer.  The Trustee and any
Paying  Agent  shall  return to the  Issuer any cash or shares of Class A Common
Stock that remain  unclaimed as provided in Section 9.4,  together with interest
or  dividends,  if any,  thereon held by them for the payment of the  Repurchase
Price  upon  Issuer  Order;  provided,  however,  that to the  extent  that  the
aggregate  amount  of cash or shares of Class A Common  Stock  deposited  by the
Issuer pursuant to Section 14.10 exceeds the aggregate  Repurchase  Price of the
Securities  or portions  thereof which the Issuer is obligated to purchase as of
the  Repurchase  Date,  then  promptly  after the  Business  Day  following  the
Repurchase  Date the Trustee shall return any such excess to the Issuer together
with interest or dividends, if any, thereon.


                                     -103-
<PAGE>


                  IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Indenture to be duly executed, all as of October 4, 1999.



                                              AMERICAN TOWER CORPORATION



                                              By /s/ Joseph L. Winn
                                              Name:  Joseph L. Winn
                                              Title: Chief Financial Officer
Attest:



By /s/ Adam Benjamin
Name:  Adam Benjamin
Title: Assistant Secretary
                                              THE BANK OF NEW YORK, not in
                                                       its individual capacity
                                                       but solely as Trustee



                                              By /s/ Van Brown
                                              Name:  Van Brown
                                              Title: Assistant Vice President


                                     -104-
<PAGE>

                                                                EXHIBIT A


                           [FORM OF FACE OF SECURITY]

THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH RESTRICTED  SECURITY OTHER
THAN ANY RESTRICTED GLOBAL SECURITY:

                  THIS  SECURITY  (OR ITS  PREDECESSOR)  AND ANY  CLASS A COMMON
STOCK  ISSUED ON  CONVERSION  HEREOF HAVE NOT BEEN  REGISTERED  UNDER THE UNITED
STATES  SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES  ACT"), OR ANY STATE
SECURITIES LAW AND MAY NOT BE OFFERED,  SOLD,  PLEDGED OR OTHERWISE  TRANSFERRED
EXCEPT  (A)(1) TO A PERSON WHO THE SELLER  REASONABLY  BELIEVES  IS A  QUALIFIED
INSTITUTIONAL  BUYER  WITHIN THE MEANING OF RULE 144A UNDER THE  SECURITIES  ACT
PURCHASING  FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED  INSTITUTIONAL
BUYER IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (2) PURSUANT TO AN
EXEMPTION  FROM  REGISTRATION  UNDER THE  SECURITIES  ACT  PROVIDED  BY RULE 144
THEREUNDER  (IF  AVAILABLE),  OR  (3)  PURSUANT  TO  AN  EFFECTIVE  REGISTRATION
STATEMENT  UNDER THE SECURITIES  ACT, AND (B) IN ACCORDANCE  WITH ALL APPLICABLE
SECURITIES LAWS OF THE STATES OF THE UNITED STATES.

                  EACH  PURCHASER OF THIS  SECURITY IS HEREBY  NOTIFIED THAT THE
SELLER OF THIS SECURITY MAY BE RELYING ON THE EXEMPTION  FROM THE  PROVISIONS OF
SECTION 5 OF THE SECURITIES ACT PROVIDED BY RULE 144A THEREUNDER.

THE  FOLLOWING  LEGEND  SHALL  APPEAR  ON THE  FACE  OF EACH  RESTRICTED  GLOBAL
SECURITY:

                  THE  SECURITIES  EVIDENCED  BY THIS GLOBAL  SECURITY (OR THEIR
PREDECESSORS)  AND ANY  CLASS A  COMMON  STOCK  ISSUED  ON  CONVERSION  OF THOSE
SECURITIES  HAVE NOT BEEN REGISTERED  UNDER THE UNITED STATES  SECURITIES ACT OF
1933, AS AMENDED (THE "SECURITIES ACT"), OR ANY STATE SECURITIES LAW AND MAY NOT
BE  OFFERED,   SOLD,  PLEDGED  OR  OTHERWISE   TRANSFERRED  IN  THE  ABSENCE  OF
REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM.
<PAGE>

                  EACH BENEFICIAL  OWNER OF AN INTEREST IN ANY OF THE SECURITIES
EVIDENCED BY THIS GLOBAL  SECURITY  (INCLUDING ANY PARTICIPANT IN THE DEPOSITARY
HOLDING  THE GLOBAL  SECURITY  THAT IS SHOWN AS HOLDING  SUCH AN INTEREST ON THE
RECORDS OF SUCH DEPOSITARY AND EACH BENEFICIAL OWNER THAT HOLDS THROUGH ANY SUCH
PARTICIPANT) AGREES FOR THE BENEFIT OF AMERICAN TOWER CORPORATION (THE "ISSUER")
THAT (I) ANY  BENEFICIAL  INTEREST IN THE  SECURITIES  AND ANY SHARES OF CLASS A
COMMON STOCK ISSUABLE UPON THEIR CONVERSION MAY BE RESOLD,  PLEDGED OR OTHERWISE
TRANSFERRED  ONLY  (A)(1) TO A PERSON WHO THE SELLER  REASONABLY  BELIEVES  IS A
QUALIFIED  INSTITUTIONAL  BUYER  WITHIN  THE  MEANING  OF RULE  144A  UNDER  THE
SECURITIES  ACT PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED
INSTITUTIONAL  BUYER IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (2)
PURSUANT TO AN EXEMPTION FROM REGISTRATION  UNDER THE SECURITIES ACT PROVIDED BY
RULE 144 THEREUNDER (IF AVAILABLE), OR (3) PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT  UNDER THE SECURITIES  ACT, AND (B) IN ACCORDANCE  WITH ALL APPLICABLE
SECURITIES LAWS OF THE STATES OF THE UNITED STATES AND (II) THE BENEFICIAL OWNER
WILL,  AND  EACH  SUBSEQUENT  BENEFICIAL  OWNER  OF AN  INTEREST  IN  ANY OF THE
SECURITIES  EVIDENCED  BY THIS  GLOBAL  SECURITY  OR ANY  CLASS A  COMMON  STOCK
ISSUABLE  UPON  CONVERSION  THEREOF IS REQUIRED TO,  NOTIFY ANY PURCHASER OF ANY
BENEFICIAL INTEREST IN THE SECURITIES OR SUCH CLASS A COMMON STOCK ISSUABLE UPON
ITS CONVERSION FROM IT OF THE RESALE RESTRICTIONS REFERRED TO IN (I) ABOVE.

                  EACH PURCHASER OF ANY BENEFICIAL INTEREST IN THE SECURITIES IS
HEREBY  NOTIFIED THAT THE SELLER OF SUCH  BENEFICIAL  INTEREST MAY BE RELYING ON
THE EXEMPTION FROM THE PROVISIONS OF SECTION 5 OF THE SECURITIES ACT PROVIDED BY
RULE 144A THEREUNDER.

THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL SECURITY:

                  THIS SECURITY IS A GLOBAL  SECURITY  WITHIN THE MEANING OF THE
INDENTURE  HEREINAFTER  REFERRED  TO  AND  IS  REGISTERED  IN  THE  NAME  OF THE
DEPOSITARY OR A NOMINEE OF THE  DEPOSITARY,  WHICH MAY BE TREATED BY THE ISSUER,
THE TRUSTEE

                                      -2-
<PAGE>

AND ANY AGENT THEREOF AS OWNER AND HOLDER OF THIS SECURITY FOR ALL PURPOSES.

THE FOLLOWING  LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL SECURITY FOR WHICH
THE DEPOSITORY TRUST COMPANY IS TO BE THE DEPOSITARY:

                  UNLESS  THIS   CERTIFICATE   IS  PRESENTED  BY  AN  AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION  ("DTC"),
TO THE ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER,  EXCHANGE,  OR PAYMENT,
AND ANY  CERTIFICATE  ISSUED IS  REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH
OTHER  NAME AS IS  REQUESTED  BY AN  AUTHORIZED  REPRESENTATIVE  OF DTC (AND ANY
PAYMENT  IS MADE TO CEDE & CO. OR TO SUCH  OTHER  ENTITY AS IS  REQUESTED  BY AN
AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR
VALUE OR  OTHERWISE BY OR TO ANY PERSON IS WRONGFUL  INASMUCH AS THE  REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

                                      -3-
<PAGE>




No.                                                               $
                                                                  [CUSIP NO.]

                           American Tower Corporation

                        6.25% Convertible Notes Due 2009


                  American Tower Corporation (the "Issuer"),  for value received
hereby  promises to pay to _________ or registered  assigns the principal sum of
_________  Dollars (which principal amount may from time to time be increased or
decreased  to such other  principal  amounts  (which,  taken  together  with the
principal  amounts  of  all  other  Outstanding  Securities,  shall  not  exceed
$360,000,000 in the aggregate at any time) by adjustments made on the records of
the Trustee  hereinafter  referred to in accordance  with the  Indenture) at the
Issuer's office or agency for said purpose in the Borough of Manhattan, The City
of New York,  on October 15, 2009, in such coin or currency of the United States
of America as at the time of payment  shall be legal  tender for the  payment of
public and private  debts,  and to pay interest,  semi-annually  on April 15 and
October 15 of each year and at maturity,  on said  principal sum in like coin or
currency at the rate per annum set forth above  beginning on April 15, 2000,  or
from the most recent date to which  interest has been paid or duly  provided for
on the  Securities.  The interest so payable on any April 15 or October 15 will,
except as otherwise provided in the Indenture referred to on the reverse hereof,
be paid to the person in whose name this  Security is registered at the close of
business on the March 31 or September 30 preceding  such April 15 or October 15,
whether or not such day is a business  day;  provided that interest may be paid,
at the  option  of the  Issuer,  by  mailing  a check  therefor  payable  to the
registered  Holder  entitled  thereto  at his last  address as it appears on the
Security register.

                  Reference is made to the further  provisions  set forth on the
reverse hereof, including without limitation


                                      -4-
<PAGE>

provisions  giving the Holder  hereof the right to convert  this  Security  into
Class A Common  Stock of the Issuer on the terms and  subject to the  conditions
and limitations  referred to on the reverse  hereof,  as more fully specified in
the  Indenture.  Such further  provisions  shall for all purposes  have the same
effect as though fully set forth at this place.

                  This  Security  shall  not be valid or  obligatory  until  the
certificate of authentication  hereon shall have been duly signed by the Trustee
acting under the Indenture.

                  IN WITNESS  WHEREOF,  the Issuer has caused this instrument to
be duly executed under its corporate seal.


Dated:

[Seal]

                                               AMERICAN TOWER CORPORATION



                                               By____________________________



                                               By____________________________


                                      -5-
<PAGE>



                          [FORM OF REVERSE OF SECURITY]

                           American Tower Corporation

                        6.25% Convertible Notes Due 2009



                  This  Security  is one  of a duly  authorized  issue  of  debt
securities  of the Issuer,  limited to up to the aggregate  principal  amount of
$300,000,000,  or up to $360,000,000 if an option is fully exercised  (except as
otherwise  provided  in the  Indenture  defined  below),  issued or to be issued
pursuant to an  indenture  dated as of October 4, 1999 (the  "Indenture"),  duly
executed and  delivered  by the Issuer to The Bank of New York,  as Trustee (the
"Trustee").  Reference  is  hereby  made to the  Indenture  and  all  indentures
supplemental  thereto for a description  of the rights,  limitations  of rights,
obligations, duties and immunities thereunder of the Trustee, the Issuer and the
Holders  (the word  "Holders"  or  "Holder"  meaning the  registered  Holders or
registered  Holder)  of the  Securities.  Terms used but not  otherwise  defined
herein shall have the meanings assigned thereto in the Indenture.

                  In case an Event of  Default,  as  defined  in the  Indenture,
shall have occurred and be  continuing,  the principal of all the Securities and
interest accrued thereon may be declared due and payable, in the manner and with
the  effect,  and subject to the  conditions,  provided  in the  Indenture.  The
Indenture  provides that in certain events a declaration of default,  a default,
or the consequences of either of them may be waived by the Holders of a majority
in  aggregate  principal  amount of the  Securities  then  outstanding  except a
default in the  payment of  principal,  Change in  Control  Repurchase  Price or
Repurchase Price of or premium,  if any, or interest on any of the Securities or
in respect  of the  conversion  of any of the  Securities.  Any such  consent or
waiver  by the  Holder of this  Security  (unless  revoked  as  provided  in the
Indenture)  shall be conclusive and binding upon such Holder and upon all future
Holders  and owners of this  Security  and any  Security  which

                                      -6-
<PAGE>

may be issued in exchange or  substitution  hereof,  whether or not any notation
thereof is made upon this Security or such other Securities.

                  The Indenture permits the Issuer and the Trustee,  without the
consent of any of the Holders under the  circumstances  described in Section 7.1
of the  Indenture,  and with  the  consent  of the  Holders  of not less  than a
majority  in  aggregate   principal   amount  of  the  Securities  at  the  time
outstanding,  evidenced as in the Indenture  provided,  to execute  supplemental
indentures adding any provisions to or changing in any manner or eliminating any
of the provisions of the Indenture or of any supplemental indenture or modifying
in any manner the rights of the Holders of the Securities; provided that no such
supplemental  indenture shall (a) extend the final maturity of any Security,  or
reduce the principal amount thereof or premium,  if any, thereon,  or reduce the
rate or extend the time of payment of interest  thereon,  or any premium payable
on the redemption  thereof, or change the place of payment where, or the coin or
currency in which, any principal,  premium or interest is payable,  or reduce or
alter the method of computation of any amount payable on redemption,  repurchase
or  repayment  thereof  (or the time at which  such  redemption,  repurchase  or
repayment  may be  made),  or  impair  or  adversely  affect  the  right  of any
Securityholder  to  institute  suit for the  payment  or  conversion  thereof or
adversely  affect the right to convert the Securities  into Class A Common Stock
of the Issuer,  in each case,  without the consent of the Holder of the Security
so affected; provided no consent of any Holder of any Security will be necessary
to permit the Trustee and the Issuer to execute  supplemental

                                      -7-
<PAGE>

indentures under the  circumstances  provided in Section 7.1(e) and Section 12.5
of the Indenture,  or (b) reduce the aforesaid percentage in principal amount of
Securities,  the  consent  of the  Holders  of  which is  required  for any such
supplemental  indenture,  without the consent of the Holders of each Security so
affected,  or (c) reduce the  percentage of  Securities  necessary to consent to
waive any past default under the Indenture to less than a majority,  without the
consent of the Holders of each  Security so  affected;  or (d) modify any of the
provisions of the Indenture  relating to  supplemental  indentures or waivers of
past defaults, except to increase any percentage provided for in Section 4.10 or
Section 7.2 of the Indenture or to provide that certain other  provisions of the
Indenture cannot be modified or waived without the consent of the Holder of each
Security affected thereby.

                  Subject to the provisions of the Indenture, the Holder of this
Security has the right, at his option, at any time until and including,  but not
after the close of business  on,  October 15, 2009  (except  that,  in case this
Security or a portion hereof shall be called for redemption and the Issuer shall
not thereafter default in making due provision for the payment of the redemption
price,  such right shall terminate with respect to this Security or such portion
hereof at the close of business on the  Business Day prior to the date fixed for
redemption),  to convert the principal  amount of this Security,  or any portion
thereof which is $1,000 or an integral  multiple of $1,000,  into fully paid and
non-assessable  shares of Class A Common  Stock of the  Issuer,  as said  shares
shall be  constituted  at the date of  conversion,  at the  conversion  price of
$24.40 in principal  amount of Securities  for each share of such Class A Common
Stock, or at the adjusted  conversion  price in effect at the date of conversion
if an adjustment has been made,  determined as provided in the  Indenture,  upon
surrender  of this  Security to the Issuer at the office or agency of the Issuer
maintained  for that purpose in the Borough of Manhattan,  The City of New York,
together with a fully executed notice substantially in the form set forth at the
foot hereof that the Holder  elects so to convert this  Security (or any portion
hereof which is an integral  multiple of $1,000  principal  amount) and, if this
Security is surrendered  for  conversion  during the period between the close of
business on March 31 or  September 30 in any year and the opening of business on
the following April 15 or October 15 and has not been called for redemption on a
redemption  date  within  such  period (or on such April 15 or October  15),  or
within five days after such period, accompanied by payment of an amount equal to
the interest  payable on such April 15 or October 15 on the principal  amount of
the  Security  being  surrendered  for  conversion.  Except as  provided  in the
preceding  sentence or as  otherwise

                                      -8-
<PAGE>

expressly  provided in the Indenture,  no payment or adjustment shall be made on
account of interest  accrued on this Security (or portion  thereof) so converted
or on account of any  dividend or  distribution  on any such Common Stock issued
upon  conversion,  but the  Holder  of record  of this  Security  on March 31 or
September  30 shall be  entitled  to receive  interest  on such  Security on the
succeeding  April  15 or  October  15  notwithstanding  the  conversion  of such
Security  prior to such April 15 or October  15. If so required by the Issuer or
the Trustee, this Security, upon surrender for conversion as aforesaid, shall be
duly  endorsed  by,  or be  accompanied  by  instruments  of  transfer,  in form
satisfactory  to the  Issuer,  duly  executed  by,  the  Holder  or by his  duly
authorized attorney. The conversion price from time to time in effect is subject
to  adjustment  as provided in the  Indenture.  No  fractions  of shares will be
issued on  conversion.  In the sole  discretion of the Board of  Directors,  any
fractional  interest  may  be  rounded  up to  the  nearest  full  share,  or an
adjustment in cash will be made for any fractional  interest,  in either case in
accordance with and as provided in the Indenture.

                  No reference  herein to the Indenture and no provision of this
Security or of the Indenture shall alter or impair the obligation of the Issuer,
which is absolute and  unconditional,  to pay the  principal of and premium,  if
any, and interest on this  Security at the place,  times,  and rate,  and in the
currency, herein prescribed.

                  The  Securities  are issuable  only as  registered  Securities
without coupons in denominations of $1,000 and any integral multiple of $1,000.

                  In the manner and subject to the  limitations  provided in the
Indenture,  this Security may be exchanged for a like aggregate principal amount
of Securities of other authorized denominations.

                  Upon due  presentment  for  registration  of  transfer of this
Security at the  above-mentioned  office or agency of the Issuer, a new Security
or  Securities  of  authorized  denominations,  for a like  aggregate  principal
amount,  will

                                      -9-
<PAGE>

be issued to the  transferee  as provided in the  Indenture.  No service  charge
shall be made for any such transfer, but the Issuer may require payment of a sum
sufficient to cover any tax or other governmental  charge that may be imposed in
relation thereto.

                  The  Securities may be redeemed at the option of the Issuer as
a whole,  or from time to time in part,  on and after  October  22,  2002,  upon
mailing a notice of such redemption not less than 20 nor more than 60 days prior
to the date fixed for  redemption  to the Holders of  Securities to be redeemed,
all as provided in the Indenture,  at the following redemption prices (expressed
in  percentages  of the  principal  amount)  together in each case with  accrued
interest to the date fixed for redemption:  If rendered during the  twelve-month
period beginning October 15, of each year indicated,

                  Year                              Redemption Price
                  ----                              ----------------

                  2002                              103.125%
                  2003                              102.083
                  2004                              101.042
                  2005 and thereafter               100%

                  The  Securities  do not have the benefit of any  sinking  fund
obligations.

                  If at any time  there  shall  occur any  Change in  Control as
defined in the Indenture  with respect to the Issuer,  each Holder of Securities
shall,  except as otherwise  provided in the Indenture,  have the right, at such
Holder's  option but subject to the conditions  set forth in the  Indenture,  to
require the Issuer to redeem on the Change in Control Repurchase Date as defined
in the Indenture all or any part of such Holder's  Securities  that is $1,000 or
an integral  multiple  thereof at a Change in Control  Repurchase Price equal to
the principal amount thereof, and accrued and unpaid interest, if any, up to but
excluding the Change in Control Repurchase Date.

                                      -10-
<PAGE>

                  Subject to  payment by the Issuer of a sum suffi  cient to pay
the amount due on  redemption,  interest on this Security (or portion  hereof if
this  Security  is  redeemed  in part)  shall cease to accrue upon the date duly
fixed for  redemption  of this  Security (or portion  hereof if this Security is
redeemed in part).

                  Subject  to the terms and  conditions  of the  Indenture,  the
Issuer shall become  obligated  to  purchase,  at the option of the Holder,  the
Securities  held by such Holder on October 22, 2006 (the  "Repurchase  Date") at
the Repurchase Price of 100% of the principal  amount thereof,  plus accrued and
unpaid interest,  if any, up to but excluding the Repurchase Date, upon delivery
of a Repurchase Notice containing the information set forth in the Indenture, at
any time from the opening of business on the date that is 20 Business Days prior
to the Repurchase  Date until the close of business on the  Repurchase  Date and
upon  delivery of the  Securities to the Paying Agent by the Holder as set forth
in the Indenture.

                  The Repurchase Price may be paid, at the option of the Issuer,
in cash or by the issuance and delivery of shares of Class A Common Stock of the
Issuer, or in any combination thereof.

                  Holders  have the right to withdraw any  Repurchase  Notice by
delivering to the Paying Agent a written notice of withdrawal in accordance with
the provisions of the Indenture.

                  If cash (and/or  securities if permitted  under the Indenture)
sufficient to pay the Repurchase  Price of all Securities or portions thereof to
be  purchased as of the  Repurchase  Date,  is  deposited  with the Trustee or a
Paying  Agent  on the  Repurchase  Date,  interest  ceases  to  accrue  on  such
Securities (or portions thereof) immediately after such Repurchase Date, and the
Holder  thereof  shall  have no other  rights as such  (other  than the right to
receive the Repurchase Price upon surrender of such Security).

                                      -11-

<PAGE>

                  The  Holder  of this  Security  and the  Class A Common  Stock
issuable on the conversion  hereof is entitled to the benefits of a Registration
Rights  Agreement  executed by the Issuer.  Whenever in this Security there is a
reference  to the  payment of interest  on, or in respect  of, a Security,  such
mention shall be deemed to include mention of the payment of liquidated  damages
to the extent payable as contemplated in such Registration Rights Agreement.

                  The Issuer, the Trustee and any authorized agent of the Issuer
or the Trustee may deem and treat the  registered  Holder hereof as the absolute
owner of this  Security  (whether  or not this  Security  shall be  overdue  and
notwithstanding any notation of ownership or other writing hereon made by anyone
other than the Issuer or the  Trustee or any  authorized  agent of the Issuer or
the  Trustee),  for the purpose of  receiving  payment of, or on account of, the
principal hereof and premium, if any, and, subject to the provisions on the face
hereof,  interest hereon and for all other purposes,  and neither the Issuer nor
the  Trustee  nor any  authorized  agent of the Issuer or the  Trustee  shall be
affected by any notice to the contrary.

                  No recourse  shall be had for the payment of the  principal of
or  premium,  if any,  or the  interest  on this  Security,  for any claim based
hereon,  or  otherwise  in  respect  hereof,  or based on or in  respect  of the
Indenture or any indenture  supplemental thereto,  against any incorporator,  as
such, or against any past, present or future  stockholder,  officer or director,
as such,  of the  Issuer or of any  partner  or  member of the  Issuer or of any
successor,  either  directly or through the Issuer or any successor,  whether by
virtue of any constitution,  statute or rule of law or by the enforcement of any
assessment or penalty or otherwise,  all such liability being, by the acceptance
thereof and as part of the consideration for the issue hereof,  expressly waived
and released.

                  The  Indenture  and this  Security  shall be  governed  by and
construed in accordance with the laws of the State of New York.


                                      -12-
<PAGE>



                [FORM OF TRUSTEE'S CERTIFICATE OF AUTHENTICATION]


                  This   is   one   of   the   Securities   described   in   the
within-mentioned Indenture.


                                             THE BANK OF NEW YORK,
                                             as Trustee



                                             _______________________________
                                              Authorized Signatory


                                      -13-
<PAGE>




                           [FORM OF CONVERSION NOTICE]

                  To:      American Tower Corporation

                  The undersigned owner of this Security hereby: (i) irrevocably
exercises  the option to convert  this  Security,  or the portion  hereof  below
designated,  for shares of Class A Common Stock of American Tower Corporation in
accordance with the terms of the Indenture referred to in this Security and (ii)
directs  that  such  shares  of  Class  A  Common  Stock  deliverable  upon  the
conversion,  together  with any check in payment for  fractional  shares and any
Security(ies)  representing any unconverted  principal amount hereof,  be issued
and delivered to the  registered  Holder hereof unless a different name has been
indicated below. If shares and/or  Security(ies) are to be delivered  registered
in the name of a person other than the undersigned, the undersigned will pay all
transfer taxes payable with respect  thereto.  Any amount required to be paid by
the undersigned on account of interest accompanies this Security.

Dated:
                                             _______________________________
                                                         Signature

Fill in for  registration of shares if to be delivered,  and of Securities if to
be issued, otherwise than to and in the name of the registered Holder.

                                             _______________________________
                                                 Social Security or Other
                                                 Taxpayer Identifying Number

_______________________________
         (Name)

_______________________________
      (Street Address)

_______________________________
  (City, State and Zip Code)
  (Please print name and address)

                                            Principal Amount to Be Converted:
                                                     (if less than all)

                                            $__________________________________



                                      -14-
<PAGE>


                  [FORM OF OPTION OF HOLDER TO ELECT REDEMPTION
                             UPON CHANGE IN CONTROL]

                  If you want to elect to have this  Security  purchased  in its
entirety by the Issuer pursuant to Article Thirteen of the Indenture,  check the
box:

                 / /

                  If you  want to  elect  to have  only a part of this  Security
purchased by the Issuer pursuant to Article Thirteen of the Indenture, state the
principal amount:
$


Dated:                                      Your Signature:____________________
                                            (Sign exactly as name appears
                                            on the face of this Security)


Signature
                                    Guarantee:________________________________
                                    (Signature  must be  guaranteed  by a member
                                    firm of the New  York  Stock  Exchange  or a
                                    commercial bank or trust company)


                                      -15-

                                                                     EXHIBIT 4.2

                           AMERICAN TOWER CORPORATION


                              THE BANK OF NEW YORK

                                     Trustee


                      ------------------------------------



                                    Indenture


                           Dated as of October 4, 1999

                      ------------------------------------


                                  $425,500,000


           (subject to increase to up to $468,050,000 in the event and
                                  to the extent
                             an option is exercised)


                        2.25% Convertible Notes Due 2009






<PAGE>
<TABLE>
<CAPTION>

                                TABLE OF CONTENTS

                                                                                                      Page
<S>                                                                                                     <C>

PARTIES.............................................................................................     1

RECITALS

         Authorization of Indenture....................................................................  1
         Compliance with Legal Requirements............................................................  1
         Purpose of and Consideration for Indenture....................................................  1

                                   ARTICLE ONE

                                   DEFINITIONS

         SECTION 1.1  Certain Terms Defined..............................................................1
                  Affiliate..............................................................................2
                  Agent    ..............................................................................2
                  Board of Directors.....................................................................2
                  Board Resolution.......................................................................2
                  Business Day...........................................................................2
                  Capital Stock..........................................................................3
                  Cash Equivalents.......................................................................3
                  Change in Control......................................................................3
                  Change in Control Repurchase Date......................................................3
                  Change in Control Repurchase Price.....................................................3
                  Class A Common Stock...................................................................4
                  Closing Date...........................................................................4
                  Common Stock...........................................................................4
                  Conversion Agent.......................................................................4
                  Conversion Price.......................................................................4
                  Corporate Trust Office.................................................................4
                  Date of Conversion.....................................................................4
                  Depositary.............................................................................4
                  Disposition............................................................................4
                  DTC      ..............................................................................5
                  Equity Interests.......................................................................5
                  Event of Default.......................................................................5
                  Excess Amount..........................................................................5
                  Exchange Act...........................................................................5
                  Global Security........................................................................5


                                       -i-
<PAGE>

                  Holder   ..............................................................................5
                  Holder of Securities...................................................................5
                  Immediate Family Member................................................................5
                  Indenture..............................................................................5
                  Issue Price............................................................................5
                  Issuer   ..............................................................................6
                  Issuer Notice..........................................................................6
                  Issuer Order...........................................................................6
                  Issuer Repurchase Notice...............................................................6
                  Issuer Repurchase Notice Date..........................................................6
                  Last Sale Price........................................................................6
                  NASDAQ   ..............................................................................7
                  Officer  ..............................................................................7
                  Officers' Certificate..................................................................7
                  Opinion of Counsel.....................................................................7
                  Original Issue Discount................................................................7
                  Outstanding............................................................................7
                  Paying Agent...........................................................................8
                  Permitted Owner........................................................................8
                  Person   ..............................................................................8
                  principal..............................................................................9
                  Principal Stockholders.................................................................9
                  Proceeding.............................................................................9
                  Redemption Date........................................................................9
                  Redemption Price.......................................................................9
                  Registrar..............................................................................9
                  Registration Rights Agreement..........................................................9
                  Related Party..........................................................................9
                  Repurchase Date........................................................................9
                  Repurchase Price.......................................................................9
                  Responsible Officer...................................................................10
                  Restricted Global Security............................................................10
                  Restricted Security...................................................................10
                  SEC      .............................................................................10
                  Security .............................................................................10
                  Securities............................................................................10
                  Securities Act........................................................................10
                  Securityholder.........................................................................5
                  Subsidiary............................................................................10
                  Surviving Person......................................................................11
                  TIA      .............................................................................11
                  Trading Day...........................................................................11


                                      -ii-

<PAGE>


                  Trustee  .............................................................................11
                  U.S. Government Obligations...........................................................11

                                   ARTICLE TWO

                                   SECURITIES

         SECTION 2.1  Form and Dating...................................................................11
         SECTION 2.2  Execution and Authentication......................................................12
         SECTION 2.3  Registrar, Paying Agent and
                          Conversion Agent..............................................................15
         SECTION 2.4  Paying Agent to Hold Money in Trust...............................................16
         SECTION 2.5  Holder Lists  ....................................................................16
         SECTION 2.6  Transfer and Exchange.............................................................16
         SECTION 2.7  Replacement Securities............................................................17
         SECTION 2.8  Outstanding Securities............................................................18
         SECTION 2.9  Temporary Securities..............................................................18
         SECTION 2.10  Cancellation ....................................................................19
         SECTION 2.11  Defaulted Interest...............................................................19
         SECTION 2.12  CUSIP Numbers....................................................................19
         SECTION 2.13  Global Securities................................................................20
         SECTION 2.14  Transfer Restrictions............................................................22

                                  ARTICLE THREE

                                    COVENANTS

         SECTION 3.1  Payment of Principal and Interest.................................................23
         SECTION 3.2  Written Statement to Trustee......................................................24
         SECTION 3.3  Corporate Existence...............................................................24
         SECTION 3.4  Reports by the Issuer.............................................................24
         SECTION 3.5  Waiver of Usury Defense...........................................................25
         SECTION 3.6  Payment of Excess Cash Dividends..................................................26
         SECTION 3.7  Registration Rights...............................................................26
         SECTION 3.8  Calculation of Original Issue
                          Discount......................................................................27


                                      -iii-

<PAGE>


                                  ARTICLE FOUR

                           REMEDIES OF THE TRUSTEE AND
                       SECURITYHOLDERS ON EVENT OF DEFAULT

         SECTION 4.1  Event of Default Defined;
                          Acceleration of Maturity; Waiver of
                          Default.......................................................................27
         SECTION 4.2  Collection of Indebtedness by
                          Trustee; Trustee May Prove Debt...............................................30
         SECTION 4.3  Application of Proceeds...........................................................33
         SECTION 4.4  Suits for Enforcement.............................................................34
         SECTION 4.5  Restoration of Rights or Abandonment
                          of Proceedings................................................................35
         SECTION 4.6  Limitations on Suits by
                          Securityholders...............................................................35
         SECTION 4.7  Unconditional Right of
                          Securityholders to Receive
                          Principal, Premium and Interest, to
                          Convert and to Institute Certain
                          Suits.........................................................................36
         SECTION 4.8  Powers and Remedies Cumulative; Delay
                          or Omission Not Waiver of Default.............................................36
         SECTION 4.9  Control by Securityholders........................................................37
         SECTION 4.10  Waiver of Past Defaults..........................................................38
         SECTION 4.11  Trustee to Give Notice of Default,
                          But May Withhold in Certain
                          Circumstances.................................................................38
         SECTION 4.12  Right of Court to Require Filing of
                          Undertaking to Pay Costs......................................................39
         SECTION 4.13  Waiver of Stay or Extension Laws.................................................39

                                  ARTICLE FIVE

                             CONCERNING THE TRUSTEE

         SECTION 5.1  Duties and Responsibilities of the
                          Trustee; During Default; Prior to
                          Default.......................................................................40
         SECTION 5.2  Certain Rights of the Trustee.....................................................42


                                      -iv-

<PAGE>

         SECTION 5.3  Trustee Not Responsible for Recitals,
                          Disposition of Securities or
                          Application of Proceeds Thereof...............................................44
         SECTION 5.4  Trustee and Agents May Hold
                          Securities; Collections, etc..................................................44
         SECTION 5.5  Compensation and Indemnification of
                          Trustee and Its Prior Claim...................................................44
         SECTION 5.6  Right of Trustee to Rely on Officers'
                          Certificate, etc..............................................................46
         SECTION 5.7  Persons Eligible for Appointment as
                          Trustee.......................................................................46
         SECTION 5.8  Resignation and Removal; Appointment
                          of Successor Trustee..........................................................47
         SECTION 5.9  Acceptance of Appointment by
                          Successor Trustee.............................................................49
         SECTION 5.10  Merger, Conversion, Consolidation or
                          Succession to Business of Trustee.............................................49

                                 ARTICLE SIX

                         CONCERNING THE SECURITYHOLDERS

         SECTION 6.1  Evidence of Action Taken by
                          Securityholders...............................................................50
         SECTION 6.2  Proof of Execution of Instruments and
                          of Holding of Securities......................................................51
         SECTION 6.3  Holders to Be Treated as Owners...................................................51
         SECTION 6.4  Securities Owned by Issuer Deemed Not
                          Outstanding...................................................................52
         SECTION 6.5  Right of Revocation of Action Taken...............................................52
         SECTION 6.6  Record Date for Consents and Waivers..............................................53

                                  ARTICLE SEVEN

                             SUPPLEMENTAL INDENTURES

         SECTION 7.1  Supplemental Indentures Without
                          Consent of Securityholders....................................................54
         SECTION 7.2  Supplemental Indentures with Consent
                          of Securityholders............................................................55


                                       -v-

<PAGE>


         SECTION 7.3  Effect of Supplemental Indenture..................................................57
         SECTION 7.4  Documents to be Given to Trustee..................................................58
         SECTION 7.5  Notation on Securities in Respect of
                                    Supplemental Indentures.............................................58

                                  ARTICLE EIGHT

                    CONSOLIDATION, MERGER, SALE OR CONVEYANCE

         SECTION 8.1  Covenant Not to Merge, Consolidate,
                          Sell or Convey Property Except
                          Under Certain Conditions......................................................58
         SECTION 8.2  Successor Corporation or Entity
                          Substituted...................................................................59
         SECTION 8.3  Opinion of Counsel and Officers'
                          Certificate to Trustee........................................................60

                                  ARTICLE NINE

                           SATISFACTION AND DISCHARGE
                         OF INDENTURE; UNCLAIMED MONEYS

         SECTION 9.1  Satisfaction and Discharge of
                          Indenture.....................................................................60
         SECTION 9.2  Application by Trustee of Funds
                          Deposited for Payment of
                          Securities....................................................................62
         SECTION 9.3  Repayment of Moneys Held by Paying
                          Agent.........................................................................62
         SECTION 9.4  Return of Moneys Held by Trustee and
                          Paying Agent Unclaimed for Two
                          Years.........................................................................63
         SECTION 9.5  Indemnity for U.S. Government
                          Obligations...................................................................63


                                      -vi-

<PAGE>

                                   ARTICLE TEN

                            MISCELLANEOUS PROVISIONS

         SECTION 10.1  Partners, Incorporators,
                          Stockholders, Officers and
                          Directors of Issue Exempt from
                          Individual Liability..........................................................64
         SECTION 10.2  Provisions of Indenture for the Sole
                          Benefit of Parties and
                          Securityholders...............................................................64
         SECTION 10.3  Successors and Assigns of Issuer
                          Bound by Indenture............................................................64
         SECTION 10.4  Notices and Demands on Issuer,
                          Trustee and Securityholders...................................................64
         SECTION 10.5  Officers' Certificates and Opinions
                          of Counsel; Statements to Be
                          Contained Therein.............................................................66
         SECTION 10.6  Payments Due on Saturdays, Sundays
                          and Legal Holidays............................................................67
         SECTION 10.7  Conflict with TIA................................................................67
         SECTION 10.8  Communications by Holders with Other
                          Holders.......................................................................68
         SECTION 10.9  Issuer to Furnish Trustee Names and
                          Addresses of Holders..........................................................68
         SECTION 10.10  New York Law to Govern..........................................................68
         SECTION 10.11  Counterparts....................................................................68
         SECTION 10.12  Effect of Headings..............................................................69

                                 ARTICLE ELEVEN

                            REDEMPTION OF SECURITIES

         SECTION 11.1  Right of Optional Redemption;
                          Prices........................................................................69
         SECTION 11.2  Notice of Redemption; Partial
                          Redemptions...................................................................69
         SECTION 11.3  Payment of Securities Called for
                          Redemption....................................................................71
         SECTION 11.4  Exclusion of Certain Securities from
                          Eligibility for Selection for
                          Redemption....................................................................72

                                                    -vii-
<PAGE>

         SECTION 11.5  Conversion Arrangement on Call for
                          Redemption....................................................................73

                                 ARTICLE TWELVE

                            CONVERSION OF SECURITIES

         SECTION 12.1  Conversion Privilege.............................................................74
         SECTION 12.2  Exercise of Conversion Privilege.................................................75
         SECTION 12.3  Fractional Shares................................................................77
         SECTION 12.4  Adjustment of Conversion Price...................................................77
         SECTION 12.5  Continuation of Conversion Privilege
                          in Case of Reclassification,
                          Reorganization, Change, Merger,
                          Consolidation or Sale of Assets...............................................82
         SECTION 12.6  Notice of Certain Events.........................................................83
         SECTION 12.7  Taxes on Conversion..............................................................84
         SECTION 12.8  Issuer to Provide Class A Common
                          Stock.........................................................................85
         SECTION 12.9  Disclaimer of Responsibility for
                          Certain Matters...............................................................86
         SECTION 12.10  Return of Funds Deposited for
                          Redemption of Converted Securities............................................87

                                ARTICLE THIRTEEN

               RIGHT TO REQUIRE REDEMPTION UPON CHANGE IN CONTROL

         SECTION 13.1  Right to Require Redemption......................................................87
         SECTION 13.2  Notices; Method of Exercising
                          Redemption Right, etc.........................................................88
         SECTION 13.3  Definition of Change in Control..................................................90
         SECTION 13.4  Limitation on Right to Require
                          Redemption....................................................................91

                                ARTICLE FOURTEEN

                REPURCHASE OF SECURITIES AT OPTION OF THE HOLDER

         SECTION 14.1  General .........................................................................92

                                                -viii-
<PAGE>

         SECTION 14.2  Issuer's Right to Elect Manner of
                          Payment of Repurchase Price...................................................94
         SECTION 14.3  Repurchase with Cash.............................................................95
         SECTION 14.4  Payment by Issuance of Class A
                          Common Stock..................................................................95
         SECTION 14.5  Notice of Election...............................................................98
         SECTION 14.6  Covenants of the Issuer.........................................................100
         SECTION 14.7  Procedure upon Repurchase.......................................................100
         SECTION 14.8  Taxes        ...................................................................101
         SECTION 14.9  Effect of Repurchase Notice.....................................................101
         SECTION 14.10  Deposit of Repurchase Price....................................................103
         SECTION 14.11  Securities Repurchased in Part.................................................103
         SECTION 14.12  Issuer to Comply with Securities
                          Laws Upon Purchase of Securities.............................................104
         SECTION 14.13  Repayment to the Issuer........................................................104
</TABLE>

SIGNATURES

EXHIBIT A -- FORM OF SECURITY



                                              -ix-

<PAGE>


                  THIS INDENTURE,  dated as of October 4, 1999 between  American
Tower Corporation,  a Delaware  corporation (the "Issuer"),  and The Bank of New
York, a New York banking corporation (the "Trustee"),

                              W I T N E S S E T H :

                  WHEREAS, the Issuer has duly authorized the issue of its 2.25%
Convertible  Notes Due 2009 (the  "Securities") of  substantially  the tenor and
amount hereinafter set forth;

                  WHEREAS,  the Issuer has duly  authorized  the  execution  and
delivery  of  this   Indenture  to  provide,   among  other   things,   for  the
authentication, delivery and administration of the Securities; and

                  WHEREAS,  all things  necessary to make this Indenture a valid
indenture and agreement according to its terms have been done;

                  NOW, THEREFORE:

                  In  consideration  of the  premises  and the  purchases of the
Securities by the Holders thereof,  the Issuer and the Trustee mutually covenant
and agree for the equal and proportionate benefit of the respective Holders from
time to time of the Securities as follows:


                                   ARTICLE ONE

                                   DEFINITIONS

                  SECTION 1.1 Certain Terms Defined. The following terms (except
as  otherwise  expressly  provided  or  unless  the  context  otherwise  clearly
requires) for all purposes of this  Indenture and of any indenture  supplemental
hereto shall have the respective  meanings specified in this Section.  All other
terms used in this Indenture which are defined in the TIA, or the definitions of
which  in the  Securities  Act are  referred  to in the TIA  (except  as  herein
otherwise  expressly provided or unless the context otherwise  requires),  shall


<PAGE>

have the meaning  assigned to such terms in the TIA and the Securities Act as in
force at the date of this  Indenture.  All accounting  terms used herein and not
expressly  defined  shall have the  meanings  given to them in  accordance  with
generally  accepted  accounting  principles,  and the term  "generally  accepted
accounting principles" shall mean such accounting principles which are generally
accepted at the date or time of any  computation.  The words "herein",  "hereof"
and  "hereunder"  and other words of similar import refer to this Indenture as a
whole and not to any particular Article, Section or other subdivision. The terms
defined in this Article include the plural as well as the singular.

                  "Affiliate"  of any  specified  Person  means any other Person
directly or indirectly  controlling or controlled by or under direct or indirect
common control with such specified Person.  For the purposes of this definition,
"control"  when used with  respect to any  specified  Person  means the power to
direct the  management  and  policies of such  Person,  directly or  indirectly,
whether  through the ownership of voting  securities,  by contract or otherwise;
and the terms  "controlling" and "controlled"  have meanings  correlative to the
foregoing.

                  "Agent" means any Registrar, Paying Agent or Conversion Agent.

                  "Board of  Directors"  means  either the Board of Directors of
the Issuer or any committee of such Board duly authorized to act on its behalf.

                  "Board  Resolution"  means a copy of one or more  resolutions,
certified by the secretary or an assistant  secretary of the Issuer to have been
duly adopted by the Board of Directors and to be in full force and effect on the
date of such certification, and delivered to the Trustee.

                  "Business  Day" means a day which in the City and State of New
York is neither  Saturday,  Sunday,  a legal  holiday nor a day on which banking
institutions  and  trust  companies  are  authorized  by  law or  regulation  or
executive order to close.

                                      -2-
<PAGE>


                  "Capital  Stock"  means  (i) in  the  case  of a  corporation,
capital stock,  (ii) in the case of any association or business entity,  any and
all shares,  interests,  participations,  rights or other  equivalents  (however
designated) or capital stock and (iii) in the case of a partnership, partnership
interests  (whether  general or limited) and any other interest or participation
that  confers on a Person the right to receive a share of the profits and losses
of, or distributions of assets of, such partnership.

                  "Cash  Equivalents"  means (i)  United  States  dollars,  (ii)
securities  issued or  directly  and fully  guaranteed  or insured by the United
States government or any agency or instrumentality  thereof having maturities of
less than one year from the date of acquisition,  (iii)  certificates of deposit
and eurodollar time deposits with maturities of less than one year from the date
of acquisition,  bankers'  acceptances with maturities of less than one year and
overnight  bank  deposits,  in each case  with any  lender  party to the  Credit
Agreements or with any domestic  commercial  bank having  capital and surplus in
excess of  $500,000,000  and a Keefe  Bank Watch  Rating of "B" or better,  (iv)
repurchase  obligations  with a term of not more than seven days for  underlying
securities  of the types  described in clauses (ii) and (iii)  entered into with
any financial  institution meeting the qualifications  specified in clause (iii)
above and (v) commercial paper having the highest rating obtainable from Moody's
Investors Service, Inc. or Standard & Poor's Ratings Services, a division of the
McGraw-Hill Companies,  Inc., and in each case maturing within nine months after
the date of acquisition.

                  "Change in Control" has the meaning  assigned to it in Section
13.3.

                  "Change in Control  Repurchase  Date" has the meaning assigned
to it in Section 13.1.

                  "Change in Control  Repurchase Price" has the meaning assigned
to it in Section 13.1.

                                      -3-
<PAGE>

                  "Class A Common  Stock"  means the Class A Common  Stock,  par
value $0.01 per share,  of the Issuer as the same exists at the Closing  Date or
as such stock may be reconstituted from time to time.

                  "Closing  Date"  means  the date (or,  if more  than one,  the
earliest date) of original issuance of the Securities.

                  "Common  Stock"  means the Class A Common  Stock,  the Class B
Common Stock,  par value $0.01 per share and the Class C Common Stock, par value
$0.01 per share, of the Issuer as the same exists at the Closing Date or as such
stock may be reconstituted from time to time.

                  "Conversion  Agent" has the meaning  assigned to it in Section
2.3.

                  "Conversion  Price"  means the Issue  Price of the  Securities
convertible  into one share of Class A Common  Stock,  subject to  adjustment in
accordance with Section 12.4.

                  "Corporate  Trust  Office"  means the office of the Trustee at
which the corporate trust business of the Trustee shall, at any particular time,
be  principally  administered,  which  office  is, at the date as of which  this
Indenture is dated, located at 101 Barclay Street, 21W, New York, NY 10286.

                  "Date of Conversion" has the meaning assigned to it in Section
12.2.

                  "Depositary"  means  with  respect to  Securities,  a clearing
agency that is  registered  as such under the Exchange Act and is  designated by
the Issuer to act as Depositary for such Securities (or any successor securities
clearing agency so registered.)

                  "Disposition" has the meaning assigned to it in Section 8.1.

                                      -4-
<PAGE>

                  "DTC"  means  The  Depository   Trust  Company,   a  New  York
corporation.

                  "Equity  Interests"  means  Capital  Stock  and all  warrants,
options or other rights to acquire Capital Stock  (including any securities that
is convertible into, or exchangeable for, Capital Stock).

                  "Event of Default"  means any event or condition  specified as
such in Section 4.1.

                  "Excess Amount" has the meaning assigned to it in Section 3.6.

                  "Exchange Act" means the  Securities  Exchange Act of 1934, as
amended.

                  "Global  Security"  means a Security that is registered in the
security register kept by the Registrar in the name of a Depositary or a nominee
thereof.

                  "Holder",  "Holder of Securities",  "Securityholder"  or other
similar  terms mean in the case of any  Security,  the Person in whose name such
Security is registered  in the security  register kept by the Registrar for that
purpose in accordance with the terms hereof.

                  "Immediate   Family  Member"   means,   with  respect  to  any
individual, such individual's spouse (past or current),  descendants (natural or
adoptive,  of the whole or half blood) of the parents of such  individual,  such
individual's   grandparents   and  parents   (natural  or  adoptive),   and  the
grandparents,  parents and descendants of parents  (natural or adoptive,  of the
whole or half blood) of such individual's spouse (past or current).

                  "Indenture"  means this instrument as originally  executed and
delivered or, if amended or  supplemented as herein  provided,  as so amended or
supplemented.

                  "Issue Price" means, in connection with the original  issuance
of a Security,  the initial issue price per

                                      -5-
<PAGE>


$1,000  principal  amount at maturity at which the Security is sold as set forth
on the face of the Security.

                  "Issuer"  means  American   Tower   Corporation,   a  Delaware
corporation, and, subject to Article Eight, its successors and assigns.

                  "Issuer  Notice"  has the  meaning  assigned  to it in Section
13.2.

                  "Issuer Order" means a written statement,  request or order of
the  Issuer  which  is  signed  in its  name by its  Chairman  of the  Board  of
Directors,  its  Chief  Executive  Officer,  its  President,  a Chief  Operating
Officer,  a Vice  President,  or  its  Chief  Financial  Officer,  and,  without
duplication,  by its Treasurer,  an Assistant  Treasurer,  its  Controller,  its
Secretary  or an  Assistant  Secretary,  of the  Issuer,  and  delivered  to the
Trustee.

                  "Issuer  Repurchase  Notice" has the meaning assigned to it in
Section 14.5.

                  "Issuer Repurchase Notice Date" has the meaning assigned to it
in Section 14.3.

                  "Last Sale  Price" on any day means the last sale price of the
Class A Common  Stock  as  reported  on the  composite  tape for New York  Stock
Exchange  listed  stocks  (or if not  listed  or  admitted  to  trading  on such
exchange,  then on the principal national securities exchange on which the Class
A Common  Stock is listed or admitted to trading,  or, if not listed or admitted
to  trading  on  any  national  securities  exchange,  on  NASDAQ  or a  similar
organization if NASDAQ is no longer reporting information) on such day or, if no
such sale takes place on such day, the last sale price for such day shall be the
average of the  closing bid and asked  prices  regular way on the New York Stock
Exchange (or, if not listed or admitted to trading on such exchange, then on the
principal  national  securities  exchange  on which the Class A Common  Stock is
listed or admitted  to trading,  or, if not listed or admitted to trading on any
national

                                      -6-
<PAGE>

securities exchange,  on NASDAQ or a similar organization if NASDAQ is no longer
reporting information) on such day.

                  "NASDAQ" means the National  Association of Securities Dealers
Automated Quotations National Market System.

                  "Officer"  means the Chairman of the Board of  Directors,  the
Chief  Executive  Officer,  the President,  a Chief  Operating  Officer,  a Vice
President,  the Chief Financial Officer, the Treasurer,  an Assistant Treasurer,
the Controller, the Secretary or an Assistant Secretary, of the Issuer.

                  "Officers'  Certificate"  means a  certificate  signed  by the
Chairman of the Board of Directors,  the Chief Executive Officer, the President,
a Chief Operating Officer, a Vice President, or the Chief Financial Officer and,
without duplication,  by the Treasurer, an Assistant Treasurer,  Controller, the
Secretary  or an  Assistant  Secretary,  of the  Issuer,  and  delivered  to the
Trustee.  Each such  certificate  shall include the  statements  provided for in
Section 10.5, if and to the extent required hereby.

                  "Opinion  of  Counsel"  means a written  opinion,  in form and
substance reasonably satisfactory to the Trustee, of counsel, who may be counsel
to the Issuer and who shall be  acceptable  to the  Trustee.  Each such  opinion
shall include the statements  provided for in Section 10.5, if and to the extent
required hereby.

                  "Original Issue Discount" of any Security means the difference
between the Issue Price and the principal  amount at maturity of the Security as
set forth on the face of the  Security.  For purposes of this  Indenture and the
Securities,  accrual of Original Issue Discount shall be calculated on the basis
of a 360-day year of twelve 30-day months, compounded semi-annually.

                  "Outstanding",  when used with reference to Securities, shall,
subject to the provision of Section 6.4,  mean, as of any  particular  time, all
Securities  authenti-

                                      -7-
<PAGE>


cated and delivered by the Trustee under this Indenture, except

                  (a)  Securities   theretofore  cancelled  by  the  Trustee  or
         delivered to the Trustee for cancellation;

                  (b)  Securities,  or  portions  thereof,  for the  payment  or
         redemption  of which  moneys in the  necessary  amount  shall have been
         deposited  in trust with the  Trustee or with any Paying  Agent  (other
         than the Issuer) or shall have been set aside,  segregated  and held in
         trust by the Issuer (if the Issuer shall act as its own Paying  Agent),
         provided  that if  such  Securities  are to be  redeemed  prior  to the
         maturity  thereof,  notice of such redemption  shall have been given as
         herein  provided,  or provision  satisfactory to the Trustee shall have
         been made for giving such notice; and

                  (c)  Securities  in  substitution  for which other  Securities
         shall have been  authenticated and delivered,  or which shall have been
         paid,  pursuant to the terms of Section 2.7 (unless proof  satisfactory
         to the Trustee is presented  that any of such  Securities  is held by a
         Person in whose  hands  such  Security  is a legal,  valid and  binding
         obligation  of the Issuer),  Securities  converted  into Class A Common
         Stock pursuant hereto and Securities not deemed Outstanding pursuant to
         and for the purposes of the last sentence of Section 11.2.

                  "Paying Agent" has the meaning assigned to it in Section 2.3.

                  "Permitted Owner" has the meaning assigned to it
in Section 13.3.

                  "Person"  means any  individual,  corporation,  part  nership,
limited  liability  company,  joint venture,  association,  joint stock company,
trust,  unincorporated  organization  or  government  or any agency or political
subdivision thereof.

                                      -8-
<PAGE>

                  "principal"  wherever used with reference to the Securities or
any Security or any portion thereof shall be deemed to include "and premium,  if
any",  accrued  Original  Issue  Discount  and  Issue  Price  whether  or not so
specified,  except  that  "principal  amount"  shall  mean  principal  amount at
maturity of the Securities whether or not so specified.  (Reference is also made
to Sections 13.2(c) and 14.9.)

                  "Principal  Stockholders"  has the  meaning  assigned to it in
         Section 13.3.

                  "Proceeding" has the meaning assigned to it in Section 12.2.

                  "Redemption  Date",  has the meaning assigned to it in Section
         11.2.

                  "Redemption  Price", when used with respect to any Security to
be  redeemed,  means the price at which it is to be  redeemed  pursuant  to this
Indenture.

                  "Registrar" has the meaning assigned to it in Section 2.3.

                  "Registration  Rights Agreement" means the Registration Rights
Agreement,  dated as of  October  4,  1999,  among the  Issuer  and the  initial
purchasers named therein.

                  "Related  Party" with respect to any individual  means (i) any
Immediate   Family  Member  of  such   individual   or  (ii)  any  Person,   the
beneficiaries, stockholders, partners, owners or Persons beneficially holding an
80% or more  controlling  interest  of which  consist of such  individual  or an
Immediate Family Member.

                  "Repurchase  Date" has the  meaning  assigned to it in Section
14.1.

                  "Repurchase  Price" has the meaning  assigned to it in Section
14.1.

                                      -9-
<PAGE>

                  "Responsible  Officer",  when used with respect to the Trustee
means  any  officer  within  the  corporate  trust  department  of the  Trustee,
including any vice  president,  assistant vice president,  assistant  secretary,
assistant  treasurer,  trust  officer  or  any  other  officer  of  the  Trustee
customarily  performing  corporate trust functions similar to those performed by
the Persons who at the time shall be such officers, respectively, or to whom any
corporate  trust matter is referred  because of such  Person's  knowledge of and
familiarity with the particular subject and who shall have direct responsibility
for the administration of this Indenture.

                  "Restricted Global Security" has the meaning assigned to it in
Section 2.1.

                  "Restricted  Security"  means any Security  issued in exchange
for an  interest  in the  Restricted  Global  Security  until  such  time as the
Restricted  Security legend contemplated in Section 2.14 need not be provided on
the Security.

                  "SEC" means the  Securities  and  Exchange  Commission  or any
successor agency.

                  "Security" or "Securities" has the meaning stated in the first
recital  of  this   Indenture  and  more   particularly   means  any  securities
authenticated and delivered under this Indenture.

                  "Securities Act" means the Securities Act of 1933, as amended.

                  "Subsidiary"   means,   with   respect  to  any  Person,   any
corporation,  association or other business entity of which more than 50% of the
total  voting  power  of  Equity  Interests  entitled  (without  regard  to  the
occurrence of any contingency) to vote in the election of directors, managers or
trustees or other  governing  body thereof is at the time owned or controlled by
such Person  (regardless of whether such Equity  Interests are owned directly or
through one or

                                      -10-
<PAGE>

more other Subsidiaries of such Person or a combination thereof).

                  "Surviving  Person" means, with respect to any Person involved
in or that  makes  any  Disposition,  the  Person  formed by or  surviving  such
Disposition or the Person to which such Disposition is made.

                  "TIA"  (except as otherwise  provided in Sections 7.1 and 7.2)
means the Trust  Indenture  Act of 1939 as in force at the date as of which this
Indenture was originally issued.

                  "Trading Day" means each Monday, Tuesday, Wednesday,  Thursday
and  Friday,  other  than  any day on which  securities  are not  traded  on the
applicable securities exchange or in the applicable securities market.

                  "Trustee"  means the entity  identified  as  "Trustee"  in the
first  paragraph  hereof and,  subject to the provisions of Article Five,  shall
also include any successor  trustee.  "Trustee"  shall also mean or include each
Person  who is then a trustee  hereunder  if at any time  there is more than one
such Person.

                  "U.S. Government Obligations" means direct obliga tions of the
United States of America, backed by its full faith and credit.


                                   ARTICLE TWO

                                   SECURITIES

                  SECTION 2.1 Form and Dating.  The Securities and the Trustee's
certificate of  authentication  shall be  substantially in the form of Exhibit A
(including the legends appearing  thereon),  the terms of which are incorporated
in and made a part of this Indenture. The Securities may have notations, legends
or endorsements required by law (including the Internal Revenue Code of 1986, as
amended),  securities exchange (including NASDAQ)

                                      -11-
<PAGE>

rules,  agreements  to which the  Issuer is  subject  or  usage,  including,  if
required by Section 2.13,  the legend contem  plated  thereby.  The Issuer shall
approve the form of the  Securities  and any notation,  legend or endorsement on
them. Each Security shall be dated the date of its authentication.

                  Upon their original  issuance,  Securities  shall be issued in
the form of one or more Global Securities  without interest coupons and shall be
registered in the name of DTC, as Depositary,  or its nominee and deposited with
the Trustee,  as custodian for DTC, for credit by DTC to the respective accounts
of  beneficial  owners of the  Securities  represented  thereby  (or such  other
accounts  as  they  may  direct).   Such  Global   Security  or  Securities  are
collectively  herein called the  "Restricted  Global  Security".  The Restricted
Global  Security and any  Restricted  Security  shall bear a different  CUSIP or
other  identifying  number from any  Security  that is not a  Restricted  Global
Security or Restricted Security.

                  SECTION 2.2 Execution and  Authentication.  Two Officers shall
sign the  Securities  for the  Issuer  by  manual or  facsimile  signature.  The
Issuer's seal shall be reproduced on the Securities.

                  If an Officer whose signature is on a Security no longer holds
that office at the time the Trustee  authenticates  the  Security,  the Security
shall be valid nevertheless.

                  A security shall not be valid until the Trustee manually signs
the certificate of authentication on the Security.  The signature of the Trustee
shall be conclusive evidence that the Security has been authenticated under this
Indenture.

                  The Trustee shall  authenticate  Securities for original issue
in the  aggregate  principal  amount  of  $425,500,000  upon  an  Issuer  Order;
provided,  however,  that if the Issuer  sells any  Securities  pursuant  to the
option in the Purchase  Agreement,  dated September 28, 1999, between the Issuer
and the initial  purchasers named therein,  then


                                      -12-
<PAGE>

the Trustee shall  authenticate  Securities  for original issue in the aggregate
principal  amount of up to $468,050,000  upon an Issuer Order.  The Issuer Order
shall specify the amount of Securities to be authenticated and the date on which
the original issue of Securities is to be authenticated. The aggregate principal
amount of Securities outstanding at any time may not exceed the amount set forth
in the previous sentence except as provided in Section 2.7.

                  The Trustee's  authentication  of  Securities  pursuant to the
next  preceding  paragraph  shall be  conditioned  upon  receipt  of each of the
following in form and  substance  reasonably  satisfactory  to the Trustee on or
prior to the Closing Date:

                  A.  An Officer's Certificate to the effect that:

                           (1) All  conditions  required to be  satisfied  under
                  this Indenture for the issuance of the Securities have been so
                  satisfied on or prior to the Closing Date; and

                           (2) No Event of Default  shall have  occurred  and be
                  continuing.

                  B. An Opinion of Counsel to the effect that:

                           (1) The execution and delivery of the Indenture,  the
                  issuance of the  Securities  and the  fulfillment of the terms
                  herein and therein  contemplated  will not  conflict  with the
                  charter or bylaws of the Issuer,  or constitute a breach of or
                  default under any material agreement,  indenture,  evidence of
                  indebtedness,  mortgage,  deed  of  trust  or  other  material
                  agreement  or  instrument  known to such  counsel to which the
                  Issuer  is a  party  or by  which  it is  bound,  or any  law,
                  administrative  regulation,  rule,  judgment,  order or decree
                  known to such counsel to be applicable to the Issuer or any of
                  its properties;

                                      -13-
<PAGE>

                           (2) The  Indenture  has been duly  authorized  by the
                  Issuer,  executed and delivered by the Issuer, and is a legal,
                  valid and  binding  agree  ment of the Issuer  enforceable  in
                  accordance with its terms,  except as such  enforceability may
                  be  limited   by   bankruptcy,   insolvency,   reorganization,
                  receivership,  moratorium  and  similar  laws  affect  ing the
                  rights and remedies of creditors  and  obligations  of debtors
                  generally  and by the effect of general  principles of equity,
                  whether applied by a court of law or equity;

                           (3) All legally required proceedings by the Issuer in
                  connection  with  the   authorization  and  issuances  of  the
                  Securities have been duly taken,  and all orders,  consents or
                  other  authorizations or approvals of any public board or body
                  legally  required for the validity of the Securities have been
                  obtained; and

                           (4) The Securities,  when executed and  authenticated
                  in accordance  with the terms of this  Indenture and delivered
                  upon  payment  therefor,  will be  legal,  valid  and  binding
                  obligations of the Issuer enforceable in accordance with their
                  terms,  except  as  such  enforceability  may  be  limited  by
                  bankruptcy,    insolvency,    reorganization,    receivership,
                  moratorium  and similar laws affecting the rights and remedies
                  of creditors and  obligations of debtors  generally and by the
                  effect of general  principles of equity,  whether applied by a
                  court of law or equity.

                  The Trustee may appoint an authenticating  agent acceptable to
the  Issuer  to  authenticate  Securities.  Unless  limited  by the term of such
appointment,  an authenticating  agent may authenticate  Securities whenever the
Trustee may do so. Each  reference in this  Indenture to  authentication  by the
Trustee includes  authentication by such agent. An authenticating  agent has the
same rights as an Agent to deal with the Issuer or an Affiliate of the Issuer.

                                      -14-
<PAGE>

                  The  Securities  shall be  issuable  only in regis  tered form
without coupons and only in  denominations  of $1,000  principal  amount and any
integral multiple thereof.

                  SECTION 2.3 Registrar, Paying Agent and Conver sion Agent. The
Issuer shall  maintain in The Borough of Manhattan in The City of New York,  New
York, an office or agency where  Securities may be presented for registration of
transfer or for exchange ("Registrar"), an office or agency where Securities may
presented for payment and repurchase ("Paying Agent"), an office or agency where
Securities may be presented for conversion ("Conversion Agent") and an office or
agency  where  notices  and  demands  to or upon the  Issuer in  respect  of the
Securities and this Indenture may be served. The Registrar shall keep a register
of the Securities and of their transfer and exchange. The Issuer may appoint one
or more  co-Registrars,  one or more  additional  Paying  Agents and one or more
additional  Conversion  Agents,  which may be inside or outside  The  Borough of
Manhattan.  The term  "Registrar"  includes any  co-Registrar,  the term "Paying
Agent"  includes any  additional  Paying Agent and the term  "Conversion  Agent"
includes any additional  Conversion  Agent. The Issuer may change any Registrar,
Paying Agent or  Conversion  Agent without  notice to any Holder.  If the Issuer
fails to  appoint or  maintain  another  person as  Registrar,  Paying  Agent or
Conversion  Agent, the Trustee shall act as such. The Issuer or any Affiliate of
the Issuer may act as  Registrar  or  Conversion  Agent.  Except for purposes of
Article Nine, the Issuer or any Affiliate of the Issuer may act as Paying Agent.

                  The Issuer shall enter into an  appropriate  agency  agreement
with any Agent not a party to this Indenture.  The agreement shall implement the
provisions  of this  Indenture  that  relate to such  Agent.  The  Issuer  shall
promptly  notify the Trustee of the name and address of any Agent not a party to
this  Indenture.  If the Issuer  fails to maintain a  Registrar,  Paying  Agent,
Conversion  Agent or agent for service of notices and demands,  or fails to give
the foregoing notice, the Trustee shall act as such.

                                      -15-
<PAGE>

                  The Issuer initially appoints the Trustee as Registrar, Paying
Agent, Conversion Agent and agent for service of notices and demands.

                  SECTION  2.4 Paying  Agent to Hold  Money in Trust.  Not later
than 11:00 a.m.,  Eastern Standard Time, on each due date of the principal of or
interest on any Securities, the Issuer shall deposit with the Paying Agent a sum
of money in  immediately  available  funds  sufficient to pay such  principal or
interest so becoming due. Subject to Section 9.2, the Paying Agent shall hold in
trust for the  benefit of  Securityholders  or the Trustee all money held by the
Paying Agent for the payment of principal of or interest on the Securities,  and
shall  notify the  Trustee in writing of any default by the Issuer in making any
such payment.  If the Issuer or an Affiliate of the Issuer acts as Paying Agent,
it shall on or  before  each due date of the  principal  of or  interest  on any
Securities  segregate the money and hold it as a separate trust fund. The Issuer
at any  time may  require  a Paying  Agent  to pay all  money  held by it to the
Trustee,  and the Trustee may at any time during the continuance of any default,
upon written  request to a Paying Agent,  require such Paying Agent to forthwith
pay to the Trustee all sums so held in trust by such  Paying  Agent.  Upon doing
so, the Paying Agent (other than the Issuer) shall have no further liability for
the money.

                  SECTION 2.5 Holder  Lists.  The Trustee  shall  preserve in as
current a form as is reasonably practicable the most recent list available to it
of the names and addresses of the Holders.  If the Trustee is not the Registrar,
the Issuer  shall  promptly  furnish to the Trustee on or before  each  interest
payment  date and at such other  times as the  Trustee  may request in writing a
list in such form and as of such date as the Trustee may reasonably  require for
the names and addresses of the Holders.

                  SECTION  2.6  Transfer  and  Exchange.   When  a  Security  is
presented to the Registrar  with a request to register a transfer  thereof,  the
Registrar  shall  register the transfer as requested,  and, when  Securities are
presented  to the  Registrar  with a  request  to  exchange  them

                                      -16-
<PAGE>

for an equal principal amount of Securities of other  authorized  denominations,
the Registrar shall make the exchange as requested; provided that every Security
presented or surrendered for  registration of transfer or exchange shall be duly
endorsed  or  be  accompanied  by a  written  instrument  of  transfer  in  form
satisfactory to the Issuer and the Registrar duly executed by the Holder thereof
or his attorney duly authorized in writing.  To permit registration of transfers
and  exchanges,  the Issuer  shall  execute and the Trustee  shall  authenticate
Securities  at the  Issuer's  request.  The Issuer  shall not be required (i) to
issue, register the transfer of or exchange Securities during a period beginning
at the  opening  of  business  on a Business  Day 15 days  before the day of any
selection of  Securities  for  redemption  under  Section 11.2 and ending at the
close of business on the day of  selection,  or (ii) to register the transfer of
or exchange any Security so selected for redemption in whole or in part,  except
the  unredeemed  portion of any Security being redeemed in part. Any exchange or
transfer shall be without charge,  except that the Issuer may require payment of
a sum  sufficient  to cover  any tax or other  governmental  charge  that may be
imposed in relation thereto,  but this provision shall not apply to any exchange
pursuant to Section 7.5 or 11.2.  Prior to due presentment  for  registration of
transfer of any  Security,  the  Trustee,  any Agent and the Issuer may deem and
treat the Person in whose name any Security is registered as the absolute  owner
of such  Security  for the  purpose of  receiving  payment of  principal  of and
interest on such Security and for all other purposes whatsoever,  whether or not
such Security is overdue, and none of the Trustee, any Agent or the Issuer shall
be affected by notice to the contrary.

                  SECTION 2.7 Replacement Securities. If a mutilated Security is
surrendered  to the  Trustee,  or if the  Holder of a Security  claims  that the
Security has been lost,  destroyed or wrongfully  taken,  and neither the Issuer
nor the Trustee has received written notice that such Security has been acquired
by a bona  fide  purchaser,  the  Issuer  shall  issue  and  the  Trustee  shall
authenticate a replacement  Security if the requirements of Section 8-405 of the
New

                                      -17-
<PAGE>

York Uniform  Commercial  Code, as in effect on the date of this Indenture,  are
met, and there shall have been delivered to the Issuer and the Trustee  evidence
to their satisfaction of the loss,  destruction or theft of any Security if such
is the case.  An  indemnity  bond will be  required  that is  sufficient  in the
judgment of the Issuer and the Trustee to protect the Issuer, the Trustee or any
Agent from any loss which any of them may suffer if a Security is replaced.  The
Issuer may charge the Holder for its expenses  (including  the fees and expenses
of the  Trustee)  in  replacing  a Security.  Every  replacement  Security is an
additional  obligation  of the Issuer.  The  provisions  of this Section 2.7 are
exclusive  and shall  preclude all other rights and remedies with respect to the
replacement or payment of mutilated, destroyed, lost or stolen Securities.

                  SECTION 2.8 Outstanding Securities. The Securities Outstanding
at any time are all of the Securities  authenticated by the Trustee,  except for
those canceled by it, those delivered to it for cancellation and those described
in this Section 2.8 as not Outstanding.

                  If a Security is replaced  pursuant to Section  2.7, it ceases
to be Outstanding  until a Responsible  Officer of the Trustee actually receives
proof  satisfactory  to it that the  replaced  Security  is held by a bona  fide
purchaser.

                  If the Paying  Agent (other than the Issuer or an Affiliate of
the Issuer) holds on a redemption date or maturity date money  sufficient to pay
the principal of and accrued  interest on Securities  payable on that date, then
on and after that date such  Securities  cease to be Outstanding and interest on
them ceases to accrue.

                  Subject  to  Section  6.4,  a  Security  does not  cease to be
Outstanding because the Issuer or an Affiliate of the Issuer holds the Security.

                  SECTION 2.9 Temporary Securities. Until defini tive Securities
are ready for  delivery,  the  Issuer  may  prepare  and,  upon the order of the
Issuer,  the  Trustee  shall  authenticate   temporary   Securities.   Temporary
Securities

                                      -18-
<PAGE>

shall  be  substantially  in the  form of  definitive  Securities  but may  have
variations  that the Issuer  considers  appropri ate for  temporary  Securities.
Without  unreasonable  delay,  the Issuer  shall  prepare and the Trustee  shall
authenticate  definitive Securities in exchange for temporary Securities.  Until
such  exchange,  temporary  Securities  shall be  entitled  to the same  rights,
benefits and privileges as definitive Securities.

                  SECTION 2.10 Cancellation.  The Issuer at any time may deliver
Securities  to the Trustee for  cancellation.  The  Registrar,  Paying Agent and
Conversion Agent shall forward to the Trustee any Securities surrendered to them
for transfer, exchange, payment or conversion. The Trustee and no one else shall
cancel all Securities surrendered for transfer, exchange, payment, conversion or
cancellation.  The Issuer may not issue new Securities to replace  Securities it
has paid or  delivered  to the  Trustee  for  cancellation  or which  have  been
converted.  All  canceled  Securities  shall be held by the Trustee and shall be
disposed of in accordance with its customary  procedures (and  certification  of
their cancellation shall be delivered to the Issuer).

                  SECTION 2.11 Defaulted  Interest.  If the Issuer defaults in a
payment of interest on the  Securities,  it shall pay the defaulted  interest in
any lawful manner plus, to the extent lawful,  interest payable on the defaulted
interest,  to the persons who are Holders on a subsequent  special  record date,
which date shall be at least five  Business  Days prior to the payment  date, in
each case at the rate provided in the  Securities and in Section 3.1. The Issuer
shall fix or cause to be fixed each such special  record date and payment  date.
At least 15 days before a special record date, the Issuer (or the Trustee in the
name of and at the expense of the Issuer)  shall forward to the Holders a notice
prepared by the Issuer that states the special record date, the related  payment
date and the amount of such interest to be paid.

                  SECTION  2.12  CUSIP  Numbers.   The  Issuer  in  issuing  the
Securities may use "CUSIP"  numbers (if then

                                      -19-
<PAGE>

generally in use),  and, if so, the Trustee shall use "CUSIP" numbers in notices
of  redemption as a  convenience  to Holders;  provided that any such notice may
state  that no  representation  is made as to the  correctness  of such  numbers
either as printed on the  Securities or as contained in any notice of redemption
and that reliance may be placed only on the other identification numbers printed
on the Securities,  and any such redemption  shall not be affected by any defect
in or omission of such numbers.  The Company will promptly notify the Trustee of
any change in the "CUSIP" numbers.

                  SECTION 2.13 Global Securities.

                  (a) Each Global  Security  authenticated  under this Indenture
shall be registered in the name of the  Depositary  designated by the Issuer for
such Global  Security or a nominee thereof and delivered to such Depositary or a
nominee  thereof or  custodian  therefor,  and each such Global  Security  shall
constitute a single Security for all purposes of this Indenture.

                  (b) Notwithstanding any other provision in this Indenture,  no
Global Security may be exchanged in whole or in part for Securities  registered,
and no transfer of a Global  Security in whole or in part may be registered,  in
the name of any Person other than the Depositary  for such Global  Security or a
nominee  thereof unless (i) such  Depositary (A) has notified the Issuer and the
Trustee in writing that it is unwilling or unable to continue as Depositary  for
such Global  Security or (B) has ceased to be a clearing  agency  registered  as
such under the  Exchange Act or  announces  an  intention  permanently  to cease
business or does in fact do so, (ii) there shall have occurred and be continuing
an Event of Default  with respect to such Global  Security,  or (iii) the Issuer
delivers an  Officers'  Certificate  to the Trustee  stating that the Issuer has
determined not to have all the Securities represented by the Global Security.

                  (c)  If any  Global  Security  is to be  exchanged  for  other
Securities or cancelled in whole, it shall be surrendered by or on behalf of the
Depositary  or its  nominee



                                      -20-
<PAGE>

to the Trustee, as Registrar, for exchange or cancellation,  as provided in this
Article.  If any Global  Security is to be  exchanged  for other  Securities  or
cancelled in part, or if another Security is to be exchanged in whole or in part
for a beneficial  interest in any Global  Security,  in each case as provided in
this Article,  then either (i) such Global  Security shall be so surrendered for
exchange or  cancellation,  as provided in this  Article,  or (ii) the principal
amount  thereof  shall be reduced or increased by an amount equal to the portion
thereof to be so exchanged or  cancelled,  or equal to the  principal  amount of
such other Security to be so exchanged for a beneficial interest therein, as the
case may be, by means of an  appropriate  adjustment  made on the records of the
Trustee,  as Registrar,  whereupon the Trustee shall  instruct the Depositary or
its authorized  representative to make a corresponding adjustment to its records
in  accordance  with its  rules  and  procedures.  Upon any  such  surrender  or
adjustment of a Global Security,  the Trustee shall as provided in this Article,
authenticate and make available for delivery any Securities issuable in exchange
for such Global  Security (or any portion  thereof) to or upon the order of, and
registered in such names as may be directed in writing by, the Depositary or its
authorized  representative.  Upon the request of the Trustee in connection  with
the occurrence of any of the events  specified in the preceding  paragraph,  the
Issuer shall  promptly  make  available  to the Trustee a  reasonable  supply of
Securities that are not in the form of Global  Securities.  The Trustee shall be
entitled to rely upon any order,  direction or request of the  Depositary or its
authorized  representative  which is given or made  pursuant to this  Article if
such  order,  direction  or  request  is  given or made in  accordance  with the
Depositary's rules and procedures.

                  (d)  Every   Security   authenticated   and   delivered   upon
registration of transfer of, or in exchange for or in lieu of, a Global Security
or any portion thereof, whether pursuant to this Article or otherwise,  shall be
authenticated  and  delivered in the form of, and shall be, a registered  Global
Security,  unless such Security is registered in the name of a Person other than
the Depositary for such Global Security or a nominee thereof, in which case

                                      -21-
<PAGE>

such  Registered  Security shall be  authenticated  and delivered in definitive,
fully registered form, without interest coupons.

                  (e) The  Depositary or its nominee,  as registered  owner of a
Global  Security,  shall be the Holder of such Global  Security for all purposes
under the Indenture and the Securities,  and owners of beneficial interests in a
Global Security shall hold such interests pursuant to the Depositary's rules and
procedures.  Accordingly,  any  such  owner's  beneficial  interest  in a Global
Security  will be shown  only on, and the  transfer  of such  interest  shall be
effected only through,  records  maintained by the  Depositary or its nominee or
its  participants  and such owners of beneficial  interests in a Global Security
will not be  considered  the owners or  holders  thereof.  Notices  given to the
Holders of the  Security  shall be deemed given if sent to the  Depositary.  The
Trustee shall have no obligation to the beneficial owners of the Securities.

                  (f) Upon the transfer of beneficial  interests in a Restricted
Global  Security  under  circumstances  permitting the removal of the Restricted
Securities legend contemplated in Section 2.14 if the Securities  represented by
such  beneficial  interest  were  not in the  form of a  Global  Security,  such
transferred beneficial interest shall be represented by a beneficial interest in
a Global Security that is not a Restricted Global Security.

                  SECTION 2.14 Transfer  Restrictions.  (a) Securities  shall be
stamped or  otherwise  be  imprinted  with the legends  containing  the transfer
restrictions  set forth on the face of the text of the  Securities  attached  as
Exhibit  A  hereto.  The  legends  so  provided  on the  face of the text of the
Securities that relate to Restricted Securities and Restricted Global Securities
may be removed  from such  Security,  upon  receipt by the  Trustee of an Issuer
Order, (i) two years from the later of issuance of the Security or the date such
Security (or any  predecessor)  was last  acquired  from an  "affiliate"  of the
Issuer  within  the  meaning  of Rule 144  under  the  Securities  Act,  (ii) in
connection with a sale made pursuant to the volume (and


                                      -22-
<PAGE>

other restrictions) of Rule 144 under the Securities Act following one year from
such time,  or (iii) in  connection  with any sale in a  transaction  registered
under the  Securities  Act,  provided  that,  if the legend is  removed  and the
Security is  subsequently  held by such an affiliate  of the Issuer,  the legend
shall be reinstated.

         (b) Each Holder of a Security  agrees to  indemnify  the Issuer and the
Trustee  against any liability  that may result from the  transfer,  exchange or
assignment  of such  Holder's  security in  violation  of any  provision of this
Indenture and/or applicable United States Federal or state securities law.

         (c) The Trustee shall have no obligation or duty to monitor,  determine
or inquire as to compliance with any restrictions on transfer imposed under this
Indenture or under  applicable  law with respect to any transfer of any interest
in  any  Security   (including  any  transfers   between  or  among   Depositary
participants or beneficial owners of interest in any Global Security) other than
to require delivery of such certificates and other  documentation or evidence as
are expressly  required by, and to do so if and when  expressly  required by the
terms of,  this  Indenture,  and to examine  the same to  determine  substantial
compliance as to form with the express requirements hereof.


                                  ARTICLE THREE

                                    COVENANTS

                  SECTION  3.1 Payment of  Principal  and  Interest.  The Issuer
covenants  and agrees that it will duly and  punctually  pay or cause to be paid
the  principal  of, and  interest  on,  each of the  Securities  at the place or
places, at the respective times and in the manner provided in the Securities and
this Indenture.  Interest on the Securities  shall be computed on the basis of a
360-day  year of twelve  30-day  months.  Each  instalment  of  interest  on the
Securities  may be paid by mailing  checks for such interest  payable to or upon
the written  order of the Holders of

                                      -23-
<PAGE>

Securities  entitled  thereto as they shall appear on the registry  books of the
Issuer.

                  SECTION 3.2  Written  Statement  to  Trustee.  The Issuer will
deliver to the Trustee, within 120 days after the end of each fiscal year of the
Issuer ending after the date hereof, an Officers'  Certificate,  stating that in
the course of the  performance by the signers of their duties as officers of the
Issuer they would  normally have knowledge of any default or  non-compliance  by
the Issuer in the perfor  mance or  fulfillment  of any  covenant,  agreement or
condition  contained  in  this  Indenture,  stating  whether  or not  they  have
knowledge of any such default or non-compliance (without regard to any period of
grace or requirement of notice provided hereunder),  and, if so, specifying each
such  default or  non-compliance  of which the signers  have  knowledge  and the
nature thereof.

         The Issuer shall deliver to the Trustee, as soon as possible and in any
event within five days after the Issuer  becomes aware of the  occurrence of any
Event of Default or an event  which,  with  notice or the lapse of time or both,
would constitute an Event of Default, an Officers' Certificate setting forth the
details of such Event of  Default  or  default  and the action  which the Issuer
proposes to take with respect thereto.

                  SECTION 3.3 Corporate Existence. Subject to Article Eight, the
Issuer will do or cause to be done all things  necessary to preserve and keep in
full force and effect its corporate existence,  rights and franchises;  provided
that the Issuer shall not be required to preserve its corporate existence or any
such right or  franchise  if the Issuer shall  determine  that the  preservation
thereof is no longer  desirable in the conduct of its business and that the loss
thereof is not  disadvantageous  in any  material  respect to the Holders of the
Securities.

                  SECTION  3.4 Reports by the Issuer.  The Issuer  covenants  to
file with the  Trustee,  within 15 days after the Issuer is required to file the
same  with  the  SEC,  copies  of the  annual  reports  and of the  information,
documents, and


                                      -24-
<PAGE>

other reports (or copies of such portions of any of the foregoing as the SEC may
from time to time by rules and  regulations  prescribe)  which the Issuer may be
required  to file with the SEC  pursuant  to Section 13 or Section  15(d) of the
Exchange Act, or if the Issuer is not required to file  information,  documents,
or reports  pursuant to either of such sections,  then to file with the Trustee,
in accordance  with rules and  regulations  prescribed  from time to time by the
SEC, such of the supplementary and periodic information,  documents, and reports
which may be required pursuant to Section 13 of the Exchange Act; or, in respect
of a security  listed and  registered  on a national  securities  exchange or on
NASDAQ as may be prescribed from time to time in such rules and regulations.  At
any time when the Issuer is not  subject to Section 13 or 15(d) of the  Exchange
Act,  upon request of Holders and  prospective  purchasers  of Securities or the
Class A Common Stock issuable upon conversion thereof,  the Issuer will promptly
furnish or cause to be  furnished to such  holders and  prospective  purchasers,
copies  of  the  information  required  to be  delivered  to  such  holders  and
prospective  purchasers of such securities pursuant to Rule 144A(d)(4) under the
Securities  Act  (or  any  successor  provision  thereto)  in  order  to  permit
compliance  with Rule 144A in  connection  with  resales by such holders of such
securities.  The Issuer will pay the  expenses of printing and  distributing  to
such holders and prospective purchasers all such documents.

                  Delivery of such  reports,  information  and  documents to the
Trustee is for  informational  purposes only and the  Trustee's  receipt of such
shall not constitute constructive notice of any information contained therein or
determinable  from  information   contained  therein,   including  the  Issuer's
compliance  with any of its  covenants  hereunder  (as to which the  Trustee  is
entitled to rely exclusively on Officers' Certificates).

                  SECTION 3.5 Waiver of Usury Defense.  The Issuer covenants (to
the extent that it may  lawfully  do so) that it shall not  assert,  plead (as a
defense or  otherwise)  or in any manner  whatsoever  claim (and shall  actively
resist any attempt to compel it to assert,  plead or claim) in any

                                      -25-
<PAGE>

action,  suit or proceeding  that the interest rate on the  Securities  violates
present or future usury or other laws  relating to the  interest  payable on any
indebtedness and shall not otherwise avail itself (and shall actively resist any
attempt to compel it to avail  itself) of the benefits or advantages of any such
laws.

                  SECTION 3.6 Payment of Excess  Cash  Dividends.  If the Issuer
shall  declare  and pay  cash  dividends  on its  Class  A  Common  Stock  in an
annualized  per share amount which exceeds the greater of (i) the annualized per
share amount of the  immediately  preceding  cash dividend on its Class A Common
Stock (as adjusted to reflect any of the events listed in Sections 12.4 or 12.5)
and (ii)  15% of the  Last  Sale  Price  of the  Class A Common  Stock as of the
Trading Day immediately  preceding the date of declaration of such dividend (the
per share amount of any such per share  excess,  to the extent of such per share
excess,  being  herein  called an "Excess  Amount"),  then in any such event the
Holders  shall have the right to  receive,  and the Issuer will pay to each such
Holder,  at the time of the payment of such Class A Common  Stock  dividend,  an
amount equal to such Excess Amount (calculated by the Issuer on the basis of the
number of shares of Class A Common Stock that would have been issued to a Holder
upon conversion of the Securities held by such Holder on the record date for the
payment of such dividend)  unless the Holder converts and receives such dividend
as a holder of Class A Common Stock.  The Issuer shall give the Trustee  written
notice of the payment of Excess Amounts to the Holders.

                  SECTION 3.7  Registration  Rights.  The Issuer agrees that the
Holders  from  time  to  time  of  Registrable  Securities  (as  defined  in the
Registration  Rights Agreement) are entitled to the benefits of the Registration
Rights Agreement. Whenever in this Indenture there is mentioned, in any context,
the payment of interest on, or in respect of, any  Security,  such mention shall
be deemed to include mention of the payment of liquidated  damages on Securities
constituting  Registrable  Securities  as  contemplated  in  Section  3  of  the
Registration  Rights  Agreement  to the  extent  that,  in  such  context,  such
liquidated  damages are, were or

                                      -26-
<PAGE>

would  be  payable  in  respect  thereof  pursuant  to  the  provisions  of  the
Registration Rights Agreement.

                  SECTION 3.8 Calculation of Original Issue Discount. The Issuer
shall file with the  Trustee  promptly  at the end of each  calendar  year (i) a
written notice specifying the amount of Original Issue Discount (including daily
rates and accrual  periods)  accrued on Outstanding  Securities as of the end of
such year and (ii) such other  specific  information  relating to such  Original
Issue Discount as may then be relevant under the Internal  Revenue Code of 1986,
as amended from time to time.


                                  ARTICLE FOUR

                           REMEDIES OF THE TRUSTEE AND
                       SECURITYHOLDERS ON EVENT OF DEFAULT

                  SECTION  4.1  Event  of  Default  Defined;  Accelera  tion  of
Maturity; Waiver of Default. "Event of Default" with respect to Securities where
used herein,  means each one of the  following  events which shall have occurred
and be continuing  (whatever the reason for such Event of Default and whether it
shall be voluntary or involuntary or be effected by operation of law or pursuant
to any judgment,  decree or order of any court or any order,  rule or regulation
of any administrative or governmental body):

                  (a) default in the payment of any  instalment of interest upon
         any of the  Securities  as and  when  the  same  shall  become  due and
         payable, and continuance of such default for a period of 30 days; or

                  (b) default in the payment of all or any part of the principal
         of or premium,  if any, upon any of the Securities as and when the same
         shall become due and payable either at maturity, upon any redemption or
         acceleration, by declaration or otherwise; or

                  (c)  failure  on the part of the  Issuer to observe or perform
         any other of the  covenants or  agreements on

                                      -27-
<PAGE>

         the part of the Issuer in the Securities or in this Indenture contained
         for a  period  of 60 days  after  the  date  on  which  written  notice
         specifying  such  failure,  stating  that such  notice is a "Notice  of
         Default" hereunder and demanding that the Issuer remedy the same, shall
         have  been  given by  registered  or  certified  mail,  return  receipt
         requested,  to the  Issuer by the  Trustee,  or to the  Issuer  and the
         Trustee by the Holders of at least 25% in aggregate principal amount of
         the Outstanding Securities; or

                  (d) a court having  jurisdiction in the premises shall enter a
         decree or order for relief in  respect of the Issuer in an  involuntary
         case or proceeding  under any applicable  Federal or State  bankruptcy,
         insolvency,  reorganization  or other  similar law now or  hereafter in
         effect,  or a decree  or order  adjudging  the  Issuer  a  bankrupt  or
         insolvent,   approving   as   properly   filed   a   petition   seeking
         reorganization, assignment, adjustment or composition of, or in respect
         of, the Issuer under any applicable  Federal or State law or appointing
         a receiver, liquidator,  assignee, custodian, trustee, sequestrator (or
         similar  official)  of the  Issuer or for any  substantial  part of its
         property or ordering the winding up or liquidation of its affairs,  and
         such decree or order shall  remain  unstayed and in effect for a period
         of 60 consecutive days; or

                  (e) the Issuer shall  commence a voluntary  case or proceeding
         under  any  applicable   Federal  or  State   bankruptcy,   insolvency,
         reorganization  or other similar law now or hereafter in effect, or any
         other case or proceeding to be adjudicated a bankrupt or insolvent,  or
         consent to the entry of an order for relief in an  involuntary  case or
         proceeding   under  any   applicable   Federal  or  State   bankruptcy,
         insolvency,  reorganization or other similar law or to the commencement
         of any  bankruptcy or insolvency  case or proceeding  against it, or to
         the  filing  by  it  of  a  petition  or  answer  or  consent   seeking
         reorganization or relief under any applicable  Federal or State law, or
         consent to the filing of such petition or to the  appointment or taking

                                      -28-
<PAGE>

         possession by a receiver, liquidator,  assignee, custodian, trustee or
         sequestrator (or similar official) of the Issuer or for any substantial
         part of its prop erty, or make any general  assignment  for the benefit
         of creditors, or the admission by it in writing of its inability to pay
         its debts  generally  as they become  due,  or the taking of  corporate
         action by the Issuer in furtherance of any such action.

                  If an Event of Default  occurs and is continuing  with respect
to the Securities,  then, and in each and every such case, unless the sum of the
Issue Price plus accrued  Original  Issue  Discount from the Closing Date of all
the Securities shall have already become due and payable,  either the Trustee or
the Holders of not less than 25% in aggregate principal amount of the Securities
then  Outstanding  hereunder,  by notice in writing  to the  Issuer  (and to the
Trustee if given by  Securityholders),  may  declare  the sum of the Issue Price
plus  accrued  Original  Issue  Discount  from  the  Closing  Date  of  all  the
Securities, and the interest accrued thereon, to be due and payable immediately,
and upon any such declaration the same shall become immediately due and payable.
This provision,  however, is subject to the condition that if, at any time after
the  Securities  shall have been so  declared  due and  payable,  and before any
judgment or decree for the payment of the moneys due shall have been obtained or
entered as hereinafter provided,  the Issuer shall pay or shall deposit with the
Trustee a sum  sufficient to pay all matured  installments  of interest upon all
the  Securities  and the  principal of any and all  Securities  which shall have
become due otherwise  than by  acceleration  (with  interest upon such principal
and, to the extent that payment of such interest is enforceable under applicable
law,  on  overdue  installments  of  interest,  at the same  rate as the rate of
interest  specified  in the Securi  ties  (giving  effect to accrual of Original
Issue  Discount),  to the date of such  payment or  deposit)  and such amount as
shall be sufficient  to cover  reasonable  compensation  to the Trustee and each
predecessor  Trustee,  their respective agents,  attorneys and counsel,  and all
other expenses and liabilities  incurred,  and all advances made, by the Trustee
and each predecessor Trustee except as a result of

                                      -29-
<PAGE>

negligence  or bad  faith,  and if any and  all  Events  of  Default  under  the
Indenture,  other than the  non-payment  of the  interest  on and  principal  of
Securities which shall have become due by  acceleration,  shall have been cured,
waived or otherwise remedied as provided  herein--then and in every such case of
such a cure the  Holders of a majority  in aggre  gate  principal  amount of the
Securities then Outstanding, by written notice to the Issuer and to the Trustee,
may  waive  all  defaults  and  rescind  and  annul  such  declaration  and  its
consequences,  but no such waiver or rescission and annulment shall extend to or
shall  affect  any  subsequent  default  or shall  impair  any right  consequent
thereon.

                  SECTION 4.2 Collection of Indebtedness by Trustee; Trustee May
Prove Debt.  The Issuer  covenants that (a) in case default shall be made in the
payment  of any  instalment  of  interest  on any of the  Securities  when  such
interest  shall  have  become  due and  payable,  and such  default  shall  have
continued  for a period of 30 days or (b) in case  default  shall be made in the
payment of all or any part of the principal of or premium, if any, on any of the
Securities  when the same  shall  have  become  due and  payable,  whether  upon
maturity or upon any redemption or by declaration or otherwise, then upon demand
of the  Trustee,  the  Issuer  will pay to the  Trustee  for the  benefit of the
Holders of the  Securities  the whole amount that then shall have become due and
payable on all such Securities for principal,  premium, if any, or interest,  as
the case may be (with  interest  to the date of such  payment  upon the  overdue
principal and, to the extent that payment of such interest is enforceable  under
applicable law, on overdue installments of interest at the same rate as the rate
of interest  specified in the  Securities,  giving effect to accrual of Original
Issue  Discount);  and in  addition  thereto,  such  further  amount as shall be
sufficient to cover the costs and expenses of collection,  including  reasonable
compensation  to the  Trustee and each  predecessor  Trustee,  their  respective
agents,  attorneys and counsel,  and any expense and liabili ties incurred,  and
all  advances  made,  by the Trustee and each  predecessor  Trustee  except as a
result of its negligence or bad faith.

                                      -30-
<PAGE>

                  Until such demand is made by the  Trustee,  the Issuer may pay
the  principal of and premium,  if any,  and interest on the  Securities  to the
registered Holders, whether or not the Securities be overdue.

                  In case the Issuer  shall fail  forthwith  to pay such amounts
upon such  demand,  the  Trustee,  in its own name and as  trustee of an express
trust, shall be entitled and empowered to institute any action or proceedings at
law or in  equity  for the  collection  of the sums so due and  unpaid,  and may
prosecute any such action or  proceedings  to judgment or final decree,  and may
enforce any such  judgment or final decree  against the Issuer or other  obligor
upon the  Securi  ties and  collect  in the  manner  provided  by law out of the
property of the Issuer or other obligor upon the Securities,  wherever situated,
the moneys adjudged or decreed to be payable.

                  In case there  shall be pending  proceedings  relative  to the
Issuer or any other  obligor  upon the  Securities  under Title 11 of the United
States Code or any other  applicable  Federal or state  bankruptcy,  insolvency,
reorganization or other similar law, or in case a receiver,  assignee or trustee
in bankruptcy or  reorganization,  liquidator,  sequestrator or similar official
shall have been appointed for or taken  possession of the Issuer or its property
or such other obligor, or in case of any other comparable  judicial  proceedings
relative to the Issuer or other obligor upon the Securities, or to the creditors
or property of the Issuer or such other obligor,  the Trustee,  irrespective  of
whether the principal of the Securities shall then be due and payable as therein
expressed or by declaration or otherwise and irrespective of whether the Trustee
shall have made any demand pursuant to the provisions of this Section,  shall be
entitled and empowered, by intervention in such proceedings or otherwise:

                  (a) to file and prove a claim or claims  for the whole  amount
         of principal, premium, if any, and interest owing and unpaid in respect
         of the Securities, and to file such other papers or documents as may be
         necessary  or  advisable  in order to have the  claims of

                                      -31-
<PAGE>

         the Trustees  (including any claim for reasonable  compensation  to the
         Trustee and each  predecessor  Trustee,  and their  respective  agents,
         attorneys  and  counsel,  and for  reimbursement  of all  expenses  and
         liabilities  incurred,  and all advances  made, by the Trustee and each
         predecessor Trustee, except as a result of negligence or bad faith) and
         of the Securityholders  allowed in any judicial proceedings relative to
         the Issuer or other obligor upon the Securities, or to the creditors or
         property of the Issuer or such other obligor,

                  (b) unless  prohibited by applicable law and  regulations,  to
         vote on behalf of the Holders of the  Securities  in any  election of a
         trustee   or  a  standby   trustee  in   arrangement,   reorganization,
         liquidation  or other  bankruptcy or insolvency  proceedings  or person
         performing similar functions in comparable proceedings, and

                  (c) to  collect  and  receive  any  moneys  or other  property
         payable  or  deliverable  on any such  claims,  and to  distribute  all
         amounts received with respect to the claims of the  Securityholders and
         of  the  Trustee  on  their  behalf;  and  any  trustee,  receiver,  or
         liquidator, custodian or other similar official is hereby authorized by
         each of the  Securityholders  to make payments to the Trustee,  and, in
         the event that the  Trustee  shall  consent  to the making of  payments
         directly to the Securityholders,  to pay to the Trustee such amounts as
         shall be sufficient to cover  reasonable  compensation  to the Trustee,
         each  predecessor  Trustee and their respective  agents,  attorneys and
         counsel,  and all other  expenses  and  liabilities  incurred,  and all
         advances made, by the Trustee and each predecessor  Trustee except as a
         result of negligence or bad faith.

                  Nothing  herein  contained  shall be deemed to  authorize  the
Trustee to  authorize  or consent to or vote for or accept or adopt on behalf of
any  Securityholder  any  plan of  reorganization,  arrangement,  adjustment  or
caption  affecting  the  Securities or the rights of any Holder

                                      -32-
<PAGE>

thereof,  or to  authorize  the  Trustee  to vote in respect of the claim of any
Securityholder  in any such  proceeding  except,  as aforesaid,  to vote for the
election of a trustee in bankruptcy or similar person.

                  All  rights of  action  and of  asserting  claims  under  this
Indenture, or under any of the Securities, may be prosecuted and enforced by the
Trustee  without  the  possession  of any of the  Securities  or the  production
thereof on any trial or other proceedings  relative thereto, and any such action
or  proceedings  instituted  by the Trustee  shall be brought in its own name as
trustee  of an express  trust,  and any  recovery  of  judgment,  subject to the
payment of the expenses,  disbursements  and  compensation of the Trustee,  each
predecessor Trustee and their respective agents and attorneys,  shall be for the
ratable benefit of the Holders of the Securities.

                  In any  proceedings  brought  by the  Trustee  (and  also  any
proceedings  involving the  interpretation of any provision of this Indenture to
which the Trustee  shall be a party) the Trustee  shall be held to represent all
the Holders of the Securities in respect of which such action was taken,  and it
shall not be necessary to make any Holders of the Securities parties to any such
proceedings.

                  SECTION 4.3 Application of Proceeds.  Any moneys  collected by
the Trustee  pursuant to this Article in respect of Securities  shall be applied
in the following order at the date or dates fixed by the Trustee and, in case of
the  distribution  of such  moneys on account of  principal  or  interest,  upon
presentation  of the several  Securities  and  stamping  (or  otherwise  noting)
thereon the  payment,  or issuing  Securities  in reduced  principal  amounts in
exchange for the presented  Securities if only partially paid, or upon surrender
thereof if fully paid:

                  FIRST: To the payment of costs and expenses, including any and
         all amounts due the Trustee under Section 5.5;

                                      -33-
<PAGE>

                  SECOND: In case the principal of the Securities shall not have
         become and be then due and  payable,  to the payment of interest on the
         Securities in default in the order of the maturity of the  installments
         of such  interest,  with interest (to the extent that such interest has
         been  collected  by the  Trustee)  upon  the  overdue  installments  of
         interest  at the same  rate as the rate of  interest  specified  in the
         Securities (giving effect to accrual of Original Issue Discount),  such
         payments to be made  ratably to the person  entitled  thereto,  without
         discrimination or preference;

                  THIRD:  In case the  principal  of the  Securities  shall have
         become and shall be then due and  payable,  to the payment of the whole
         amount then owing and unpaid  upon all the  Securities  for  principal,
         premium, if any, and interest, with interest upon the overdue principal
         and  premium,  if any,  and (to the extent that such  interest has been
         collected by the Trustee) upon overdue  installments of interest at the
         same rate as the rate of interest  specified in the Securities  (giving
         effect to accrual of Original Issue Discount);  and in case such moneys
         shall be insufficient to pay in full the whole amount so due and unpaid
         upon the Securities, then to the payment of such principal, premium, if
         any, and interest,  without  preference  or priority of principal  (and
         premium,  if any) over  interest,  or of interest over  principal  (and
         premium,  if any),  or of any  instalment  of  interest  over any other
         instalment  of interest,  or of any Security  over any other  Security,
         ratably  to the  aggregate  of such  principal,  premium,  if any,  and
         accrued and unpaid interest; and

                  FOURTH: To the payment of the remainder, if any, to the Issuer
         or any other person lawfully entitled thereto.

                  SECTION 4.4 Suits for Enforcement. In case an Event of Default
has  occurred,  has not been  waived and is  continuing,  the Trustee may in its
discretion  proceed  to protect  and  enforce  the  rights  vested in it by this

                                      -34-
<PAGE>


Indenture by such  appropriate  judicial  proceedings  as the Trustee shall deem
most  effectual to protect and enforce any of such  rights,  either at law or in
equity or in bankruptcy or otherwise,  whether for the specific  enforcement  of
any covenant or agreement  contained in this Indenture or in aid of the exercise
of any  power  granted  in this  Indenture  or to  enforce  any  other  legal or
equitable right vested in the Trustee by this Indenture or by law.

                  SECTION  4.5   Restoration   of  Rights  or   Abandonment   of
Proceedings.  In case the Trustee or any Securityholder  shall have proceeded to
enforce  any right under this  Indenture  and such  proceedings  shall have been
discontinued  or  abandoned  for any  reason,  or  shall  have  been  determined
adversely to the Trustee or to such Securityholder, then and in every such case,
subject to any determination in such proceeding, the Issuer, the Trustee and the
Securityholders  shall be restored  severally and  respectively  to their former
positions and rights hereunder,  and thereafter all rights,  remedies and powers
of the Issuer, the Trustee and the  Securityholders  shall continue as though no
such proceedings had been taken.

                  SECTION  4.6  Limitations  on Suits by  Security  holders.  No
Holder of any  Security  shall  have any right by virtue or by  availing  of any
provision of this Indenture to institute any action or  proceeding,  judicial or
otherwise,  at law or in equity or in bankruptcy  or otherwise  upon or under or
with respect to this Indenture, or for the appoint ment of a trustee,  receiver,
liquidator,  custodian  or  other  similar  official  or for  any  other  remedy
hereunder, unless such Holder previously shall have given to the Trustee written
notice of a continuing  Event of Default as herein before  provided,  and unless
also the  Holders  of not less  than 25% in  aggregate  principal  amount of the
Securities then  Outstanding  shall have made written request upon a Responsible
Officer of the Trustee to institute  such action or  proceedings in its own name
as  trustee   hereunder  and  shall  have  offered  to  the  Trustee   indemnity
satisfactory to it as it may require against the costs, expenses and liabilities
to be incurred  therein or thereby and the Trustee for 45 days after its receipt
of such notice,

                                      -35-
<PAGE>

request and offer of indemnity shall have failed to institute any such action or
proceedings and no direction  inconsistent  with such written request shall have
been given to a Responsible  Officer of the Trustee  pursuant to Section 4.9; it
being understood and intended,  and being expressly  covenanted by the Holder of
every Security with every other Holder of the  Securities and the Trustee,  that
no one or more Holders of Securities shall have any right in any manner whatever
by virtue or by availing of any provision of this  Indenture to affect,  disturb
or prejudice the rights of any other Holder of Securities,  or to obtain or seek
to obtain priority over or preference to any other such Holder or to enforce any
right under this  Indenture,  except in the manner  herein  provided and for the
equal,  ratable  and  common  benefit  of all  Holders  of  Securities.  For the
protection and  enforcement  of the  provisions of this Section,  each and every
Securityholder  and the Trustee shall be entitled to such relief as can be given
either at law or in equity.

                  SECTION 4.7 Unconditional Right of Security holders to Receive
Principal,  Premium and  Interest,  to Convert and to Institute  Certain  Suits.
Notwithstanding  any other  provision in this Indenture and any provision of any
Security,  the right of any Holder of any  Security  to  receive  payment of the
principal of and premium, if any, and inter est on such Security on or after the
respective due dates  expressed in such Security (or, in the case of redemption,
on the  applicable  Redemption  Date or  Repurchase  Date),  or to convert  such
Security  in  accordance  with  Article  Twelve,  or to  institute  suit for the
enforcement of any such payment on or after such  respective  dates,  or for the
enforcement of such conversion right,  shall not be impaired or affected without
the written consent of such Holder, with a copy thereof to the Trustee.

                  SECTION 4.8 Powers and Remedies Cumulative;  Delay or Omission
Not Waiver of Default.  Except as  provided in Sections  2.7, no right or remedy
herein  conferred upon or reserved to the Trustee or to the  Securityholders  is
intended  to be  exclusive  of any other  right or remedy,  and every  right and
remedy shall,  to the extent  permitted by

                                      -36-
<PAGE>

law,  be  cumulative  and in  addition  to every  other  right and remedy  given
hereunder or now or  hereafter  existing at law or in equity or  otherwise.  The
assertion or employment of any right or remedy  hereunder,  or otherwise,  shall
not prevent the  concurrent  assertion or  employment  of any other  appropriate
right or remedy.

                  No delay or omission of the Trustee or of any Holder of any of
the Securities to exercise any right or power accruing upon any Event of Default
occurring and  continuing  as aforesaid  shall impair any such right or power or
shall  be  construed  to  be a  waiver  of  any  such  Event  of  Default  or an
acquiescence  therein; and, subject to Section 4.6, every power and remedy given
by this  Indenture  or by law to the  Trustee or to the  Securityholders  may be
exercised from time to time, and as often as shall be deemed  expedient,  by the
Trustee or by the Securityholders, as the case may be.

                  SECTION  4.9  Control  by  Securityholders.  The  Holders of a
majority in aggregate principal amount of the Securities at the time Outstanding
shall  have the right to  direct  in  writing  the  time,  method,  and place of
conducting any proceeding for any remedy available to the Trustee, or exercising
any  trust or  power  conferred  on the  Trustee;  provided  that  such  written
direction  shall not be otherwise than in accordance with law and the provisions
of this  Indenture;  and provided  further that  (subject to the  provisions  of
Section  5.1) the  Trustee  shall  have the right to  decline to follow any such
direction if the Trustee,  being advised by counsel,  shall  determine  that the
action or proceeding so directed may expose the Trustee to personal liability or
if the  Trustee  in good  faith  by its  board  of  directors  or the  executive
committee thereof shall so determine that the actions or forbearances  specified
in or pursuant to such direction would be unduly prejudicial to the interests of
Holders of the Securities not joining in the giving of said direction,  it being
understood  that  (subject  to Section  5.1) the  Trustee  shall have no duty to
ascertain whether or not such actions or forbearances are unduly  prejudicial to
such Holders.

                                      -37-
<PAGE>

                  Nothing  in this  Indenture  shall  impair  the  right  of the
Trustee in its  discretion  to take any action  deemed proper by the Trustee and
which is not inconsistent with such direction by Securityholders.

                  SECTION 4.10 Waiver of Past Defaults. Prior to the declaration
of the maturity of the  Securities  as provided in Section 4.1, the Holders of a
majority in aggregate principal amount of the Securities at the time Outstanding
may on behalf of the  Holders of all the  Securities  waive any past  default or
Event of Default hereunder and its consequences,  except a default in respect of
a covenant or provision  hereof which cannot be modified or amended  without the
consent of the Holder of each Security affected (including,  without limitation,
the provisions with respect to payment of principal of and premium,  if any, and
interest on such  Security or with respect to conversion  of such  Security).  A
copy of any such waiver or consent shall be delivered to the Trustee.

                  Upon any such waiver, such default shall cease to exist and be
deemed to have been  cured and not to have  occurred,  and any Event of  Default
arising  therefrom shall be deemed to have been cured,  and not to have occurred
for every  purpose of this  Indenture;  but no such waiver  shall  extend to any
subsequent or other  default or Event of Default or impair any right  consequent
thereon.

                  SECTION  4.11  Trustee  to Give  Notice  of  Default,  But May
Withhold in Certain  Circumstances.  The Trustee shall, at the Issuer's expense,
transmit  to the  Holders  of  Securities,  as the names and  addresses  of such
Holders appear on the registry books,  notice by mail of all defaults known to a
Responsible Officer of the Trustee, such notice to be transmitted within 90 days
after the occurrence thereof,  unless such defaults shall have been cured before
the giving of such notice (the term  "default" or "defaults" for the purposes of
this Section  being hereby  defined to mean any event or condition  which is, or
with  notice  or  lapse of time or both  would  become,  an  Event of  Default);
provided that,  except in the case of default in the payment of the principal of
or premium,  if any, or interest on any

                                      -38-
<PAGE>

of the Securities,  the Trustee shall be protected in withholding such notice if
and so long as the  board of  directors,  the  executive  committee,  or a trust
committee of directors or trustees and/or Responsible Officers of the Trustee in
good faith determines that the withholding of such notice is in the interests of
the Securityholders.

                  SECTION 4.12 Right of Court to Require  Filing of  Undertaking
to Pay  Costs.  All  parties to this  Indenture  agree,  and each  Holder of any
Security by his  acceptance  thereof  shall be deemed to have  agreed,  that any
court may in its  discretion  require,  in any suit for the  enforcement  of any
right or remedy under this  Indenture or in any suit against the Trustee for any
action  taken,  suffered  or omitted by it as  Trustee,  the filing by any party
litigant in such suit other than the Trustee of an  undertaking to pay the costs
of such suit, and that such court may in its discretion assess reasonable costs,
including attorneys' fees, against any party litigant in such suit including the
Trustee,  having  due  regard  to the  merits  and good  faith of the  claims or
defenses made by such party  litigant;  but the provisions of this Section shall
not apply to any suit  instituted by the Trustee,  to any suit instituted by any
Securityholder  or group of  Securityholders  holding in the aggregate more than
10% in aggregate principal amount of the Securities at the time Outstanding,  or
to any suit instituted by any  Securityholder for the enforcement of the payment
of the  principal  of or  interest  on any  Security  on or  after  the due date
expressed  in such  Security  or for the  enforcement  of a right to convert any
Security in accordance with Article Twelve.

                  SECTION  4.13  Waiver of Stay or  Extension  Laws.  The Issuer
covenants  (to the extent  that it may  lawfully  do so) that it will not at any
time  insist  upon,  or plead,  or in any  manner  whatsoever  claim or take the
benefit or advantage of, any stay or extension law wherever  enacted,  now or at
any time hereafter in force,  which may affect the covenants or the  performance
of this  Indenture;  and the Issuer (to the extent  that it may  lawfully do so)
hereby  expressly  waives all benefit or advantage of any such law and covenants
that it will not  hinder,  delay or impede  the


                                      -39-
<PAGE>

execution of any power herein granted to the Trustee, but will suffer and permit
the execution of every such power as though no such law had been enacted.

                                  ARTICLE FIVE

                             CONCERNING THE TRUSTEE

                  SECTION 5.1 Duties and Responsibilities of the Trustee; During
Default;  Prior to Default.  With  respect to the Holders of  Securities  issued
hereunder, the Trustee, prior to the occurrence of an Event of Default and after
the  curing or  waiving  of all  Events  of  Default  which  may have  occurred,
undertakes to perform such duties and only such duties as are  specifically  set
forth in this  Indenture.  In case an  Event  of  Default  with  respect  to the
Securities has occurred and is continuing  (which has not been cured or waived),
the Trustee  shall  exercise  such of the rights and powers vested in it by this
Indenture,  and use the same  degree of care and skill in their  exercise,  as a
prudent person would exercise or use under the  circumstances  in the conduct of
such person's own affairs.

                  No provision of this  Indenture  shall be construed to relieve
the Trustee from  liability  for its own  negligent  action,  its own  negligent
failure to act or its own wilful misconduct or bad faith, except that

                  (a) prior to the  occurrence  of an Event of Default and after
         the  curing or waiving  of all such  Events of  Default  which may have
         occurred:

                           (i) the duties and  obligations  of the Trustee  with
                  respect  to  Securities  shall  be  determined  solely  by the
                  express  provisions of this  Indenture,  and the Trustee shall
                  not be liable  except for the  performance  of such duties and
                  obligations as are  specifically  set forth in this Indenture,
                  and no implied  covenants  or  obligations  shall be read into
                  this Indenture against the Trustee; and

                                      -40-
<PAGE>

                           (ii) in the  absence  of bad faith on the part of the
                  Trustee, the Trustee may conclusively rely, as to the truth of
                  the statements and the correct ness of the opinions  expressed
                  therein,   upon   any   resolution,    statement,    officer's
                  certificate,  or any other certificate,  instrument or opinion
                  furnished to the Trustee and conforming to the requirements of
                  this  Indenture;  but in the  case  of  any  such  statements,
                  certificates  or opinions  which by any  provision  hereof are
                  specifically  required to be  furnished  to the  Trustee,  the
                  Trustee shall be under a duty to examine the same to determine
                  whether  or not  they  conform  to the  requirements  of  this
                  Indenture;

                  (b) the Trustee  shall not be liable for any error of judgment
         made in good faith by a Responsible Officer or Responsible  Officers of
         the Trustee,  unless it shall be proved that the Trustee was  negligent
         in ascertaining the pertinent facts; and

                  (c) the Trustee shall not be liable with respect to any action
         taken or omitted to be taken by it in good faith in accordance with the
         direction  of Holders  pursuant  to Section  4.9  relating to the time,
         method and place of conducting any proceeding for any remedy  available
         to the Trustee,  or exercising  any trust or power  conferred  upon the
         Trustee, under this Indenture.

                  None  of the  provisions  contained  in this  Indenture  shall
require the Trustee to expend or risk its own funds or otherwise  incur personal
financial  liability in the  performance of any of its duties or in the exercise
of any of its  rights  or  powers,  if there  shall  be  reasonable  ground  for
believing  that the repayment of such funds or adequate  indemnity  against such
liability is not reasonably assured to it.

                                      -41-
<PAGE>

                  SECTION 5.2 Certain Rights of the Trustee.  Subject to Section
5.1:

                  (a) the Trustee may  conclusively  rely and shall be protected
         in acting or  refraining  from  acting upon any  resolution,  Officers'
         Certificate or any other certificate,  statement,  instrument, opinion,
         report, notice,  request,  direction,  consent, order, bond, debenture,
         note, coupon,  security or other paper or document believed by it to be
         genuine and to have been  signed or  presented  by the proper  party or
         parties;

                  (b) any  request,  direction,  order or demand  of the  Issuer
         mentioned  herein  shall  be  sufficiently  evidenced  by an  Officers'
         Certificate  (unless  other  evidence  in  respect  thereof  be  herein
         specifically prescribed);  and any resolution of the Board of Directors
         may be  evidenced  to the Trustee by a copy  thereof  certified  by the
         Secretary or an Assistant Secretary of the Issuer;

                  (c) the Trustee may consult with  counsel of its  selection at
         the expense of the Issuer and any advice or Opinion of Counsel shall be
         full and complete authorization and protection in respect of any action
         taken,  suffered or omitted to be taken by it  hereunder  in good faith
         and in accordance with such advice or Opinion of Counsel;

                  (d) the Trustee  shall be under no  obligation to exercise any
         of the trusts or powers vested in it by this  Indenture at the request,
         order  or  direction  of  any of the  Securityholders  pursuant  to the
         provisions of this Indenture,  unless such  Securityholders  shall have
         offered  to the  Trustee  security  or  indemnity  satisfactory  to the
         Trustee  against the costs,  expenses  and  liabilities  which might be
         incurred therein or thereby;

                  (e) the  Trustee  shall not be liable  for any  action  taken,
         suffered  or  omitted  by it in good  faith  and  believed  by it to be
         authorized or within the

                                      -42-
<PAGE>

         discretion, rights or powers conferred upon it by this Indenture;

                  (f) prior to the  occurrence of an Event of Default  hereunder
         and after the curing or waiver of all Events of  Default,  the  Trustee
         shall not be bound to make any investigation  into the facts or matters
         stated in any resolution,  certificate, statement, instrument, opinion,
         report, notice,  request,  consent, order, approval,  appraisal,  bond,
         debenture,  note, coupon,  security,  or other paper or document unless
         requested  in  writing  so to do by  the  Holders  of not  less  than a
         majority  in  aggregate   principal   amount  of  the  Securities  then
         Outstanding,   but  a  Responsible  Officer  of  the  Trustee,  in  its
         discretion,  may make such further inquiries or investigation into such
         facts or matters as it may see fit, and, if the Trustee shall determine
         to make such inquiry or investigation,  it shall be entitled to examine
         the books,  records and premises of the Issuer,  personally or by agent
         or attorney;  provided that, if the payment within a reasonable time to
         the Trustee of the costs, expenses or liabilities likely to be incurred
         by it in the  making of such  investigation  is, in the  opinion of the
         Trustee, not reasonably assured to the Trustee by the security afforded
         to it by the terms of this Indenture, the Trustee may require indemnity
         satisfactory  to the Trustee  against such expenses or liabilities as a
         condition to proceeding;  the expenses of every such examination  shall
         be paid by the  Issuer or, if paid by the  Trustee  or any  predecessor
         trustee, shall be repaid by the Issuer upon demand;

                  (g) the  Trustee  may  execute  any of the  trusts  or  powers
         hereunder  or perform  any duties  hereunder  either  directly or by or
         through agents or attorneys not regularly in its employ and the Trustee
         shall not be  responsible  for any misconduct or negligence on the part
         of any such agent or attorney appointed with due care by it hereunder;

                                      -43-
<PAGE>

                  (h) the  Trustee  shall not be  deemed  to have  notice of any
         Default or Event of Default unless a Responsible Officer of the Trustee
         has  actual  knowledge  thereof or unless  written  notice of any event
         which is in fact such a  default  is  received  by the  Trustee  at the
         Corporate Trust Office of the Trustee,  and such notice  references the
         Securities and this Indenture; and

                  (i)  the  rights,  privileges,   protections,  immunities  and
         benefits given to the Trustee, including, without limitation, its right
         to be  indemnified,  are extended to, and shall be enforceable  by, the
         Trustee  in  each  of its  capacities  hereunder,  and to  each  agent,
         custodian and other Person employed to act hereunder.

                  SECTION 5.3 Trustee Not Responsible for Recitals,  Disposition
of Securities or Application of Proceeds Thereof.  The recitals contained herein
and in the Securi ties,  except the Trustee's  certificates  of  authentication,
shall be taken as the  statements  of the  Issuer,  and the  Trustee  assumes no
responsibility   for  the   correctness  of  the  same.  The  Trustee  makes  no
representation  as to the validity or  sufficiency  of this  Indenture or of the
Securi ties. The Trustee shall not be accountable  for the use or application by
the Issuer of any of the Securities or of the proceeds thereof.

                  SECTION   5.4   Trustee   and  Agents  May  Hold   Securities;
Collections,  etc. The Trustee or any agent of the Issuer or the Trustee, in its
individual or any other capacity,  may become the owner or pledgee of Securities
with the same rights it would have if it were not the Trustee or such agent and,
subject to Section 5.8, may otherwise deal with the Issuer and receive, collect,
hold and retain  collections  from the Issuer with the same rights it would have
if it were not the Trustee or such agent.

                  SECTION 5.5  Compensation and  Indemnification  of Trustee and
Its Prior Claim. The Issuer covenants and agrees to pay to the Trustee from time
to time, and the


                                      -44-
<PAGE>

Trustee shall be entitled to, such  compensation  as the Company and the Trustee
shall from time to time agree in writing for all services that the Trustee shall
provide hereunder (which  compensation  shall not be limited by any provision of
law in regard to the  compensation  of a trustee  of an  express  trust) and the
Issuer covenants and agrees to pay or reimburse the Trustee and each predecessor
Trustee upon its request for all reasonable expenses, disbursements and advances
incurred or made by or on behalf of it in accordance  with any of the provisions
of this Indenture (including the compensation and the expenses and disbursements
of its counsel and of all agents and other  persons not regularly in its employ)
except  any  such  expense,  disbursement  or  advance  as may  arise  from  its
negligence or bad faith.  The Issuer also covenants to indemnify the Trustee and
each predecessor Trustee for, and to hold it harmless against, any loss, damage,
claim,  liability  or expense  including  taxes  (other  than taxes  based upon,
measured  by or  determined  by the  income of the  Trustee),  incurred  without
negligence or bad faith on its part,  arising out of or in  connection  with the
acceptance or  administration  of this Indenture or the trusts hereunder and its
duties  hereunder,  including  but not  limited  to the  costs and  expenses  of
defending  itself against or  investigating  any claim (whether  asserted by the
Company,  any Holder or any other  Person) or liability in  connection  with the
exercise  or  performance  of  any  of  its  powers  or  duties  hereunder.  The
obligations  of the Issuer under this Section to  compensate  and  indemnify the
Trustee and each  predecessor  Trustee and to pay or  reimburse  the Trustee and
each  predecessor  Trustee  for  expenses,   disbursements  and  advances  shall
constitute additional  indebtedness hereunder and shall survive the satisfaction
and discharge of this Indenture.  Such additional indebtedness shall be a senior
claim to that of the Securities upon all property and funds held or collected by
the Trustee as such,  except funds held in trust for the payment of principal of
or interest on particular Securities, and the Securities are hereby subordinated
to such senior claim.  When the Trustee incurs  expenses or renders  services in
connection  with an Event of Default  specified in Section 4.1 or in  connection
with Article  Four  hereof,  the expenses  (including  the  reasonable  fees and

                                      -45-
<PAGE>

expenses of its  counsel)  and the  compensation  for the service in  connection
therewith  are  intended  to  constitute  expenses of  administration  under any
bankruptcy law.

                  SECTION 5.6 Right of Trustee to Rely on Officers' Certificate,
etc.  Subject to Sections  5.1 and 5.2,  whenever in the  administration  of the
trusts of this Indenture the Trustee shall deem it necessary or desirable that a
matter be proved or  established  prior to taking or  suffering  or omitting any
action hereunder, such matter unless other evidence in respect thereof be herein
specifically  prescribed)  may, in the absence of negligence or bad faith on the
part of the Trustee,  be deemed to be conclusively  proved and established by an
Officers'  Certificate  delivered to the Trustee,  and such certificate,  in the
absence of  negligence  or bad faith on the part of the  Trustee,  shall be full
warrant to the Trustee for any action taken, suffered or omitted by it under the
provisions of this Indenture upon the faith thereof.

                  SECTION 5.7 Persons  Eligible for Appointment as Trustee.  The
Trustee  hereunder  shall at all  times be a  corporation  organized  and  doing
business  under the laws of the United  States of America or of any State or the
District of Columbia.  The Trustee and its direct parent shall at all times have
a combined capital and surplus of at least $50,000,000,  and which is authorized
under such laws to exercise corporate trust powers and is subject to supervision
or  examination  by Federal,  State or District of Columbia  authority.  If such
corporation publishes reports of condition at least annually, pursuant to law or
to the requirements of the aforesaid  supervising or examining  authority,  then
for the  purposes  of this  Section,  the  combined  capital and surplus of such
corporation  shall be deemed to be its combined capital and surplus as set forth
in its most recent  report of  condition so  published.  In case at any time the
Trustee  shall cease to be eligible in  accordance  with the  provisions of this
Section,  the Trustee shall resign immediately in the manner and with the effect
specified in Section 5.8.

                                      -46-
<PAGE>

                  The  provisions of this Section 5.7 are in  furtherance of and
subject to Section 310(a) of the TIA.

                  SECTION 5.8 Resignation and Removal;  Appointment of Successor
Trustee.  (a) The  Trustee may at any time  resign by giving  written  notice of
resignation to the Issuer. Upon receiving such notice of resignation, the Issuer
shall promptly appoint a successor  trustee by written  instrument in duplicate,
executed by authority  of the Board of  Directors,  one copy of each  instrument
shall be  delivered  to the  resigning  Trustee  and one  copy to the  successor
trustee.  If no successor trustee shall have been so appointed and have accepted
appointment  within 30 days after the giving of such notice of resignation,  the
resigning  trustee may  petition  any court of  competent  jurisdiction  for the
appointment of a successor  trustee,  or any Security holder who has been a bona
fide Holder of a Security or Securities for at least six months may,  subject to
the  provisions of Section  4.12, on behalf of himself and all others  similarly
situated,  petition any such court for the appointment of a successor trustee at
the expense of the Issuer. Such court may thereupon,  after such notice, if any,
as it may deem proper and prescribe, appoint a successor trustee.

                  (b) If at any time any of the following shall occur:

                (i) the  Trustee  shall fail to comply  with the pro  visions of
         Section 310(b) of the TIA after written request  therefor by the Issuer
         or by any  Securityholder who has been a bona fide Holder of a Security
         or Securities for at least six months; or

               (ii) the Trustee  shall cease to be eligible in  accordance  with
         the  provisions  of Section 5.7 and shall fail to resign after  written
         request therefor by the Issuer or by any Securityholders;

                  (iii) the Trustee shall became  incapable of acting,  or shall
         be adjudged a bankrupt or insolvent, or a receiver or liquidator of the
         Trustee or of its property  shall be appointed,  or any public  officer
         shall  take  charge or control of the  Trustee  or of its

                                      -47-
<PAGE>

         property or affairs for the purpose of rehabilitation,  conservation or
         liquidation;

then,  in any such  case,  the  Issuer may  remove  the  Trustee  and  appoint a
successor trustee by written instrument, in duplicate,  executed by order of the
Board  of  Directors  of the  Issuer,  one  copy of  which  instrument  shall be
delivered to the Trustee so removed and one copy to the  successor  trustee,  or
subject to the  provisions of Section 4.12,  any  Securityholder  who has been a
bona fide  Holder of a  Security  or  Securities  for at least six months may on
behalf of  himself  and all others  similarly  situated,  petition  any court of
competent  jurisdiction  for the removal of the Trustee and the appointment of a
successor  trustee.  Such court may thereupon,  after such notice, if any, as it
may deem  proper and  prescribe,  remove the  Trustee  and  appoint a  successor
trustee.

                  (c) The Holders of a majority in aggregate principal amount of
the  Securities at the time  Outstanding  may at any time remove the Trustee and
appoint a successor  trustee by  delivering  to the  Trustee so removed,  to the
successor  trustee so appointed  and to the Issuer the evidence  provided for in
Section 6.1 of the action in that regard taken by the Securityholders.

                  (d)  Any  resignation  or  removal  of  the  Trustee  and  any
appointment  of a successor  trustee  pursuant to any of the  provisions of this
Section  5.8 shall  become  effective  upon  acceptance  of  appointment  by the
successor trustee as provided in Section 5.9.

                  (e) The Issuer shall give notice of each resigna tion and each
removal of the Trustee and each  appointment  of a successor  trustee by mailing
written  notice of such  event by  first-class  mail,  postage  prepaid,  to the
Holders  of  Securities  affected  as their  names and  addresses  appear in the
Security  register.  Each notice shall include the name of the successor trustee
and the address of its principal corporate trust office.

                                      -48-
<PAGE>

                  SECTION 5.9  Acceptance of  Appointment by Succes sor Trustee.
Any  successor  trustee  appointed as provided in Section 5.8 shall  execute and
deliver to the Issuer and to its  predecessor  trustee an  instrument  accepting
such  appointment  hereunder,  and thereupon the  resignation  or removal of the
predecessor  trustee shall become effective and such successor trustee,  without
any  further  act,  deed or  conveyance,  shall  become  vested with all rights,
powers, duties and obligations of its predecessor hereunder, with like effect as
if originally named as trustee herein; but, nevertheless, on the written request
of the Issuer or of the  successor  trustee,  upon  payment of its charges  then
unpaid,  the trustee  ceasing to act shall,  subject to Section 9.4, pay over to
the  successor  trustee  all moneys at the time held by it  hereunder  and shall
execute and deliver an instrument  prepared by the Issuer  transferring  to such
successor trustee all such rights, powers, duties and obligations.  Upon request
of any such successor trustee,  the Issuer shall execute any and all instruments
in  writing  for more fully and  certainly  vesting  in and  confirming  to such
successor trustee all such rights and powers.  Any trustee ceasing to act shall,
nevertheless,  retain a prior claim upon all property or funds held or collected
by such trustee to secure any amounts then due it pursuant to the  provisions of
Section 5.5.

                  Upon  acceptance  of  appointment  by a  successor  trustee as
provided  in  this  Section  5.9,  the  Issuer  shall  mail  notice  thereof  by
first-class  mail to the Holders of Securities  at their last  addresses as they
shall appear in the Security  register.  If the  acceptance  of  appointment  is
substantially  contemporaneous with the resignation,  then the notice called for
by the preceding  sentence may be combined with the notice called for by Section
5.8. If the Issuer fails to mail such notice within 10 days after  acceptance of
appointment  by the successor  trustee,  the successor  trustee shall cause such
notice to be mailed at the expense of the Issuer.

                  SECTION 5.10 Merger,  Conversion,  Consolidation or Succession
to Business of Trustee.  Any corporation into which the Trustee may be merged or
converted or with which

                                      -49-
<PAGE>

it may be consolidated, or any corporation resulting from any merger, conversion
or  consolidation  to which the  Trustee  shall be a party,  or any  corporation
succeeding  to the cor  porate  trust  business  of the  Trustee,  shall  be the
successor of the Trustee  hereunder without the execution or filing of any paper
or any further act on the part of any of the parties hereto,  anything herein to
the contrary notwithstanding;  provided that such corporation shall be qualified
under  the  provisions  of  Section  310(b)  of the TIA and  eligible  under the
provisions of Section 5.7.

                  In  case at the  time  such  successor  to the  Trustee  shall
succeed to the trusts created by this Indenture any of the Securities shall have
been  authenticated  but not  delivered,  any such  successor to the Trustee may
adopt the certificate of authentication  of any predecessor  trustee and deliver
such  Securities  so  authenticated;  and,  in  case  at  that  time  any of the
Securities shall not have been authen ticated,  any successor to the Trustee may
authenticate such Securities either in the name of any predecessor  hereunder or
in the name of the  successor  trustee;  and in all such cases such  certificate
shall have the full force  which it is  anywhere  in the  Securities  or in this
Indenture provided that the certificate of the Trustee shall have; provided that
the right to adopt the certificate of authentication of any predecessor  trustee
or to  authenticate  Securities  of any  series  in the name of any  predecessor
trustee shall apply only to its successor or successors by merger, conversion or
consolidation.


                                   ARTICLE SIX

                         CONCERNING THE SECURITYHOLDERS

                  SECTION 6.1 Evidence of Action Taken by Security holders.  Any
request,  demand,  authorization,  direction,  notice,  consent, waiver or other
action provided by this Indenture to be given or taken by Securityholders may be
embodied in and evidenced by one or more  instruments of  substantially  similar
tenor signed by such  Securityholders in person or by an agent duly appointed in
writing;  and,

                                      -50-
<PAGE>

except  as  herein  otherwise  expressly  provided,  such  action  shall  become
effective  when such  instrument  or  instruments  are delivered to the Trustee.
Proof of execution of any such  instrument or of a writing  appointing  any such
agent shall be  sufficient  for any purpose of this  Indenture  and  (subject to
Sections 5.1 and 5.2) conclusive in favor of the Trustee and the Issuer, if made
in the manner provided in this Article.

                  SECTION 6.2 Proof of Execution of  Instruments  and of Holding
of  Securities.  Subject  to  Sections  5.1 and  5.2,  the  fact and date of the
execution of any instrument by any  Securityholder or his agent or proxy, or the
authority of such an agent or proxy to execute such an instrument  may be proved
(i) by the affidavit of a witness of such execution,  (ii) by a certificate of a
notary public (or other officer  authorized  by law to take  acknowledgments  of
deeds) as to such execution,  or (iii) in accordance with such reasonable  rules
and  regulations  as may be prescribed by the Trustee or in such manner as shall
be reasonably  satisfactory to the Trustee.  The holding of Securities  shall be
proved by the Security register or by a certificate of the registrar thereof.

                  SECTION  6.3  Holders to Be  Treated  as Owners.  Prior to due
presentment of a Security for registration of transfer, the Issuer, the Trustee,
any  Agent and any agent of the  Issuer  or the  Trustee  may deem and treat the
person in whose name any Security shall be registered upon the Security register
as the absolute  owner of such Security  (whether or not such Security  shall be
overdue and  notwithstanding any notation of ownership or other writing thereon)
for the purpose of receiving  payment of or on account of the  principal of and,
subject to the provisions of this  Indenture,  interest on such Security and for
all other  purposes;  and  neither  the Issuer nor the  Trustee nor any Agent or
agent of the  Issuer  or the  Trustee  shall be  affected  by any  notice to the
contrary. All such payments so made to any such person, or upon his order, shall
be valid,  and, to the extent of the sum or sums so paid,  effectual  to satisfy
and discharge the liability for moneys payable upon any such Security.

                                      -51-
<PAGE>

                  SECTION 6.4 Securities Owned by Issuer Deemed Not Outstanding.
In  determining  whether  the  Holders  of the  requisite  principal  amount  of
Outstanding Securities have concurred in any direction,  consent or waiver under
this Indenture, Securities which are owned by the Issuer or any other obligor on
the  Securities or any Affiliate of the Issuer or of such other obligor shall be
disregarded  and  deemed  not to be  Outstanding  for the  purpose  of any  such
determination,  except that for the purpose of  determining  whether the Trustee
shall be  protected  in relying on any such  direction,  consent or waiver  only
Securities which the Trustee knows are so owned shall be so disregarded.  Securi
ties so  owned  which  have  been  pledged  in good  faith  may be  regarded  as
Outstanding  if the pledgee  establishes to the  satisfaction  of the Trustee in
writing the pledgee's  right so to act with respect to such  Securities and that
the pledgee is not the Issuer or any other  obligor upon the  Securities  or any
Affiliate  of the  Issuer or of such other  obligor.  In case of a dispute as to
such right,  the advice of counsel  shall be full  protection  in respect of any
decision made by the Trustee in accordance with such advice. Upon request of the
Trustee,  the  Issuer  shall  furnish  to  the  Trustee  promptly  an  Officers'
Certificate listing and identifying all Securities,  if any, known by the Issuer
to be owned or held by or for the account of any of the above-described Persons;
and,  subject to Sections 5.1 and 5.2,  the Trustee  shall be entitled to accept
such Officers' Certificate as conclusive evidence of the facts therein set forth
and of the fact that all Securities not listed therein are  Outstanding  for the
purpose of any such determination.

                  SECTION 6.5 Right of Revocation  of Action Taken.  At any time
prior to (but not after) the  evidencing to the Trustee,  as provided in Section
6.1, of the taking of any action by the Holders of the  percentage  in aggregate
principal  amount of the  Securities  specified in this  Indenture in connection
with such action,  any Holder of a Security the serial  number of which is shown
by the evidence to be included  among the serial  numbers of the  Securities the
Holders of which have  consented to such action may, by filing written notice at
the  Corporate  Trust  Office  and upon proof of  holding  as  provided  in this
Article,  revoke such

                                      -52-
<PAGE>

action so far as concerns  such  Security.  Except as afore said any such action
taken by the Holder of any Security  shall be  conclusive  and binding upon such
Holder  and upon all  future  Holders  and  owners of such  Security  and of any
Securities  issued in exchange or  substitution  therefor or on  registration or
transfer thereof,  irrespective of whether or not any notation in regard thereto
is made  upon  any  such  Security.  Any  action  taken  by the  Holders  of the
percentage in aggregate  principal  amount of the  Securities  specified in this
Indenture in connection with such action shall be conclusively  binding upon the
Issuer, the Trustee and the Holders of all the Securities.

                  SECTION 6.6 Record Date for Consents  and Waivers.  The Issuer
may,  but shall not be  obligated  to,  direct the Trustee to establish a record
date for the purpose of determining  the Persons  entitled to (i) waive any past
default with respect to the  Securities  in accordance  with Section 4.10,  (ii)
consent to any  supplemental  indenture in accordance  with Section 7.2 or (iii)
waive compliance with any term, condition or provision of any covenant hereunder
(if the Indenture should expressly provide for such waiver). If a record date is
fixed,  the Holders of Securities on such record date, or their duly  designated
proxies, and any such Persons, shall be entitled to waive any such past default,
consent to any such  supplemental  indenture or waive  compliance  with any such
term, condition or provision,  whether or not such Holder remains a Holder after
such  record  date;  provided,  however,  that  unless such waiver or consent is
obtained  from  the  Holders,  or  duly  designated  proxies,  of the  requisite
principal  amount of Outstanding  Securities prior to the date which is the 90th
day after such record date,  any such waiver or consent  previously  given shall
automatically  and without  further  action by any Holder be cancelled and of no
further effect.

                                      -53-
<PAGE>


                                  ARTICLE SEVEN

                             SUPPLEMENTAL INDENTURES

                  SECTION  7.1  Supplemental   Indentures   Without  Consent  of
Securityholders.  The Issuer,  when  authorized  by a resolution of its Board of
Directors,  and the  Trustee may from time to time and at any time enter into an
indenture  or  indentures  supplemental  hereto  (which  shall  conform  to  the
provisions of the TIA as in force at the date of the execution  thereof) for one
or more of the following purposes:

                  (a) to convey,  transfer,  assign,  mortgage  or pledge to the
         Trustee as security for the Securities any property or assets;

                  (b) to evidence the  succession of another  corporation to the
         Issuer, or successive successions,  and the assumption by the successor
         corporation of the covenants,  agreements and obligations of the Issuer
         pursuant to Article Eight;

                  (c) to  add  to the  covenants  of  the  Issuer  such  further
         covenants,  restrictions,  conditions or provisions  (including without
         limitation  provisions necessary or desirable to qualify this Indenture
         under the TIA) as its Board of Directors and the Trustee shall consider
         to be for the protection or benefit of the Holders of  Securities,  and
         to make the occurrence, or the occurrence and continuance, of a default
         in  any  such  additional   covenants,   restrictions,   conditions  or
         provisions an Event of Default permitting the enforcement of all or any
         of the several remedies provided in this Indenture as herein set forth;
         provided that in respect of any such additional covenant,  restriction,
         condition or provision  such  supplemental  indenture may provide for a
         particular  period of grace after default  (which period may be shorter
         or  longer  than that  allowed  in the case of other  defaults)  or may
         provide for an immediate  enforcement  upon such an Event of Default or
         may limit

                                      -54-
<PAGE>

         the remedies  available to the Trustee upon such an Event of Default or
         may limit the right of the Holders of a majority in aggregate principal
         amount of the Securities to waive such an Event of Default;

                  (d) to cure any  ambiguity  or to  correct or  supplement  any
         provision  contained herein or in any supplemental  indenture which may
         be defective or inconsistent with any other provision  contained herein
         or in any  supplemental  indenture  or to make such other  provision in
         regard to matters or questions  arising  under this  Indenture or under
         any supplemental indenture as the Board of Directors may deem necessary
         or desirable,  provided that no such action shall adversely  affect the
         interests of the Holders of the Securities;

                  (e) to provide for adjustment of conversion rights pursuant to
         Section 12.5; or

                  (f) to evidence the removal or  resignation of the Trustee and
         the appointment of a successor  Trustee or Trustees pursuant to Article
         Five.

                  The Trustee is hereby  authorized  to join in the execution of
any such supplemental  indenture, to make any further appropriate agreements and
stipulations,  which may be therein  contained,  and to accept  the  conveyance,
transfer,  assignment,  mortgage or pledge of any property  thereunder,  but the
Trustee  shall not be  obligated to enter into any such  supplemental  indenture
which  affects  adversely  the  Trustee's  own  rights,  duties,  immunities  or
liabilities under this Indenture or otherwise.

                  Any  supplemental  indenture  authorized by the  provisions of
this  Section 7.1 may be  executed  without the consent of the Holders of any of
the Securities at the time Outstanding, notwithstanding any of the provisions of
Section 7.2.

                  SECTION   7.2   Supplemental   Indentures   with   Consent  of
Securityholders.  With the consent (evidenced as provided

                                      -55-
<PAGE>

in  Article  Six) of the  Holders  of not  less  than a  majority  in  aggregate
principal  amount of the Securities at the time  Outstanding,  the Issuer,  when
authorized by a resolution of its Board of Directors,  and the Trustee may, from
time to time and at any time, enter into an indenture or indentures supplemental
hereto (which shall conform to the provisions of the TIA as in force at the date
of execution thereof) for the purpose of adding any provisions to or changing in
any manner or  eliminating  any of the  provisions  of this  Indenture or of any
supplemental  indenture  or of modifying in any manner the rights of the Holders
of the Securities; provided that no such supplemental indenture shall (a) extend
the final  maturity of any Security,  or reduce the principal  amount thereof or
premium,  if any,  thereon,  or reduce the rate or extend the time of payment of
interest thereon,  or any premium payable upon the redemption thereof, or change
the rate of accrual or extend the time of payment in  connection  with  Original
Issue Discount  thereon,  or change the place of payment  where,  or the coin or
currency in which, any principal,  premium or interest is payable,  or reduce or
alter the method of calculation of any amount payable on redemption,  repurchase
or repayment  thereof (or the time at which any such  redemption,  repurchase or
repayment  may be  made),  or  impair  or  adversely  affect  the  right  of any
Securityholder  to  institute  suit for the  payment  or  conversion  thereof or
adversely  affect the right to convert the Securities in accordance with Article
Twelve,  in each case,  without  the  consent of the Holder of each  Security so
affected;  provided no consent of any Holder of any Security  shall be necessary
under  this  Section  7.2 to  permit  the  Trustee  and the  Issuer  to  execute
supplemental  indentures  pursuant to Section  7.1(e) and  Section  12.5 of this
Indenture;  or (b)  reduce  the  aforesaid  percentage  in  principal  amount of
Outstanding Securities,  the consent of the Holders of which is required for any
such supplemental indenture, without the consent of the Holders of each Security
so affected;  or (c) reduce the percentage of Securities necessary to consent to
waive any past default under this Indenture to less than a majority, without the
consent of the Holders of each  Security so  affected;  or (d) modify any of the
provisions  of this  Section  or  Section  4.10,  except  to  increase  any such
percentage

                                      -56-
<PAGE>

provided in either such Section or to provide that certain  other  provisions of
this Indenture cannot be modified or waived without the consent of the Holder of
each Security affected thereby.

                  Upon the  request of the  Issuer,  accompanied  by a copy of a
resolution of the Board of Directors (which resolution may provide general terms
or  parameters  for such action and may provide that the specific  terms of such
action may be  determined in  accordance  with or pursuant to an Issuer  Order),
certified by the Secretary or an Assistant Secretary of the Issuer,  authorizing
the execution of any such supplemental  indenture,  and upon the filing with the
Trustee of evidence of the consent of  Securityholders  and other documents,  if
any,  required by Section  6.1,  the  Trustee  shall join with the Issuer in the
execution of such  supplemental  indenture  unless such  supplemental  indenture
adversely  affects the Trustee' own rights,  duties,  immunities or  liabilities
under  this  Indenture  or  otherwise,  in  which  case the  Trustee  may in its
discretion,  but  shall  not be  obligated  to,  enter  into  such  supplemental
indenture.

                  It  shall   not  be   necessary   for  the   consent   of  the
Securityholders  under  this  Section  to  approve  the  particular  form of any
proposed  supplemental  indenture,  but it shall be  sufficient  if such consent
shall approve the substance thereof.

                  Promptly  after the execution by the Issuer and the Trustee of
any  supplemental  indenture  pursuant to the  provisions of this  Section,  the
Issuer  shall  mail a notice  thereof  by  first-class  mail to the  Holders  of
Securities at their  addresses as they shall appear on the registry books of the
Issuer,  setting  forth in  general  terms the  substance  of such  supplemental
indenture. Any failure of the Issuer to mail such notice, or any defect therein,
shall  not,  however,  in any way  impair or  affect  the  validity  of any such
supplemental indenture.

                  SECTION  7.3  Effect  of  Supplemental  Indenture.   Upon  the
execution of any supplemental  indenture pursuant to the provisions hereof, this
Indenture  shall be and be deemed

                                      -57-
<PAGE>

to be modified and amended in accordance  therewith and the  respective  rights,
limitations of rights,  obligations,  duties and immunities under this Indenture
of the Trustee,  the Issuer and the Holders of  Securities  shall  thereafter be
determined,  exercised  and enforced  hereunder  subject in all respects to such
modifications  and  amendments,  and all the  terms and  conditions  of any such
supplemental  indenture  shall  be and be  deemed  to be part of the  terms  and
conditions of this Indenture for any and all purposes.

                  SECTION 7.4  Documents  to be Given to Trustee.  The  Trustee,
subject to the  provisions of Sections 5.1 and 5.2, may upon request  receive an
Officers'  Certificate and an Opinion of Counsel as conclusive evidence that any
such  supplemental  indenture  complies with the  applicable  provisions of this
Indenture.

                  SECTION 7.5 Notation on Securities in Respect of  Supplemental
Indentures.  Securities  authenticated  and delivered after the execution of any
supplemental  indenture  pursuant to the  provisions  of this Article may bear a
notation as to any matter provided for by such  supplemental  indenture.  If the
Issuer shall so  determine,  new  Securities  so modified as to conform,  in the
opinion  of the  Board  of  Directors,  to any  modification  of this  Indenture
contained  in any such  supplemental  indenture  may be  prepared by the Issuer,
authenticated  by the Trustee and delivered in exchange for the Securities  then
Outstanding.


                                  ARTICLE EIGHT

                    CONSOLIDATION, MERGER, SALE OR CONVEYANCE

                  SECTION 8.1 Covenant Not to Merge, Consolidate, Sell or Convey
Property  Except Under Certain  Conditions.  The Issuer may not  consolidate  or
merge with or into (whether or not the Issuer is the Surviving Person), or sell,
assign, transfer, lease, convey or otherwise dispose of all or substantially all
of its  properties  or assets in one or more  related  transactions,  to another
Person (each a "Disposition"), unless:

                                      -58-
<PAGE>

         (i) the Surviving  Person is a corporation  organized or existing under
         the laws of the United  States,  any state  thereof or the  District of
         Columbia;

         (ii) the  Surviving  Person (if other than the Issuer)  assumes all the
         obligations of the Issuer under the Securities and this Indenture,  and
         makes provision for conversion  rights in accordance with Section 12.5,
         pursuant to a supplemental indenture in a form reasonably  satisfactory
         to the Trustee; and

         (iii) immediately after such Disposition,  no Event of Default or event
         that,  after the giving of notice or the passage of time or both, would
         be an Event of Default, shall have occurred and be continuing.

                  SECTION 8.2 Successor  Corporation or Entity  Substituted.  In
case of any such consolidation,  merger, sale or conveyance,  and following such
an assumption by the successor  corporation,  partnership  or limited  liability
company,  such successor  corporation,  partnership or limited liability company
shall succeed to and be substituted  for the Issuer,  with the same effect as if
it had been named herein.

                  Such successor  corporation,  partnership or limited liability
company may cause to be signed,  and may issue  either in its own name or in the
name  of the  Issuer  prior  to  such  succession  any or all of the  Securities
issuable  hereunder which  theretofore  shall not have been signed by the Issuer
and delivered to the Trustee; and, upon the order of such successor corporation,
partnership or limited liability company,  instead of the Issuer, and subject to
all the terms,  conditions and  limitations in this  Indenture  prescribed,  the
Trustee shall  authenticate  and shall deliver any Securities  which  previously
shall  have been  signed  and  delivered  by the  officers  of the Issuer to the
Trustee for authentication, and any Securities which such successor corporation,
partnership or limited liability company

                                      -59-
<PAGE>

thereafter  shall  cause to be signed  and  delivered  to the  Trustee  for that
purpose.  All of the  Securities  so issued shall in all respects  have the same
legal rank and benefit under this  Indenture as the  Securities  theretofore  or
thereafter  issued in accordance  with the terms of this Indenture as though all
of such Securities had been issued at the date of the execution hereof.

                  In case of any  such  consolidation,  merger,  sale,  lease or
conveyance,  such changes in phraseology  and form (but not in substance) may be
made in the Securities thereafter to be issued as may be appropriate.

                  In the  event of any such  sale or  conveyance  (other  than a
conveyance  by  way  of  lease),  the  Issuer  or  any  successor   corporation,
partnership or limited  liability  company which shall  theretofore  have become
such in the  manner  described  in this  Article  shall be  discharged  from all
obligations  and covenants  under this  Indenture and the  Securities and may be
liquidated and dissolved.

                  SECTION 8.3 Opinion of Counsel and  Officers'  Certificate  to
Trustee.  The Trustee,  subject to the  provisions  of Sections 5.1 and 5.2, may
upon request  receive an Opinion of Counsel  prepared in accordance with Section
10.5 and an Officers' Certificate (confirming  satisfaction of the conditions of
clauses (i), (ii) and (iii) of Section 8.1) as conclusive evidence that any such
consolidation,  merger, sale, lease or conveyance,  and any such assumption, and
any such liquidation or dissolution,  complies with the applicable provisions of
this Indenture.


                                  ARTICLE NINE

                           SATISFACTION AND DISCHARGE
                         OF INDENTURE; UNCLAIMED MONEYS

                  SECTION 9.1 Satisfaction and Discharge of Indenture. If at any
time (a) the Issuer  shall have paid or caused to be paid the  principal  of and
premium, if any, and interest on all the Securities then Outstanding  hereunder,

                                      -60-
<PAGE>


as and when the same shall have become due and payable,  or (b) the Issuer shall
have  delivered  to the  Trustee for  cancellation  all  Securities  theretofore
authenticated  (other than any Securities which shall have been destroyed,  lost
or stolen and which shall have been replaced or paid as provided in Section 2.7)
or (c) (i) all such  Securities  not  theretofore  delivered  to the Trustee for
cancellation (x) shall have become due and payable, or (y) are by their terms to
become due and payable within one year or are to be called for redemption within
one year under  arrangements  reasonably  satisfactory  to the  Trustee  for the
giving of notice of  redemption,  and (ii) the  Issuer  shall  have  irrevocably
deposited or caused to be  deposited  with the Trustee as trust funds the entire
amount in cash (other than moneys  repaid by the Trustee or any Paying  Agent to
the  Issuer in  accordance  with  Section  9.4) or U.S.  Government  Obligations
maturing as to principal  and interest at such times and in such amounts as will
insure the  availability  of cash, or a combination  thereof,  sufficient in the
opinion  of a  nationally  recognized  firm of  independent  public  accountants
expressed in a written  certification  thereof delivered to the Trustee,  to pay
the principal of and interest on all Securities on each date that such principal
or interest is due and payable;  and if, in any such case, the Issuer shall also
pay or cause to be paid all other sums  payable  hereunder  by the Issuer,  then
this  Indenture  shall cease to be of further effect (except as to (i) rights of
registration  of  transfer,  conversion  and  exchange  of  Securities,  and the
Issuer's right of optional  redemption  contemplated  in clause  (c)(i)(y) above
(but not  otherwise  and not  including  the  Holders'  right of  redemption  or
repurchase   contemplated  by  Article  Thirteen  or  Article  Fourteen),   (ii)
substitution  of  apparently  mutilated,  defaced,  destroyed,  lost  or  stolen
Securities,  (iii) rights of the Holders of  Securities  to receive  payments of
principal  thereof and premium,  if any and  interest  thereon upon the original
stated  due  dates  therefor  (but not  upon  acceleration),  (iv)  the  rights,
obligations  and  immunities  of the Trustee  hereunder,  including any right to
compensation  and  indemnification  under Section 5.5, and (v) the rights of the
Holders of  Securities as  beneficiaries  hereof with respect to the property so
deposited with the

                                      -61-
<PAGE>

Trustee  payable  to all or any of  them),  and the  Trustee,  on  Issuer  Order
accompanied by an Officers'  Certificate  and an Opinion of Counsel stating that
the  provisions  of this  Section  have been  complied  with and at the cost and
expense of the Issuer,  shall execute proper instruments  prepared by the Issuer
acknowledging  such  satisfaction of and discharging  this Indenture,  provided,
that the rights of Holders of the  Securities  to receive  amounts in respect of
principal of, premium, if any, and interest on the Securities held by them shall
not be delayed  longer  than  required  by  then-applicable  mandatory  rules or
policies of any securities  exchange upon which the  Securities  are listed.  In
addition,  in connection with the satisfaction and discharge  pursuant to clause
(c)(i)(y)  above,  the Trustee shall give notice to the Holders of Securities of
such satisfaction and discharge.  The Issuer agrees to reimburse the Trustee for
any  costs or  expenses  thereafter  reasonably  and  properly  incurred  and to
compensate  the Trustee for any  services  thereafter  reasonably  and  properly
rendered by the Trustee in  connection  with this  Indenture or the  Securities.

                  Notwithstanding   the   satisfaction  and  discharge  of  this
Indenture,  the obligations of the Issuer to the Trustee under Section 5.5 shall
survive.

                  SECTION  9.2  Application  by Trustee of Funds  Deposited  for
Payment  of  Securities.  Subject  to Section  9.4,  all  moneys and  securities
deposited  with the  Trustee  pursuant to Section 9.1 shall be held in trust and
applied  by it to the  payment,  either  directly  or through  any Paying  Agent
(including  the Issuer  acting as its own Paying  Agent),  to the Holders of the
particular  Securities  for the  payment or  redemption  of which such moneys or
Securities  have been  deposited  with the Trustee of all sums due and to become
due thereon for principal and interest;  but such moneys or securities  need not
be segregated from other funds except to the extent required by law.

                  SECTION  9.3  Repayment  of Moneys  Held by Paying  Agent.  In
connection with the satisfaction and discharge of this Indenture with respect to
Securities,  all moneys then

                                      -62-
<PAGE>

held by any Paying Agent under the  provisions  of this  Indenture  shall,  upon
Issuer Order,  be repaid to it or paid to the Trustee and thereupon  such Paying
Agent shall be released from all further liability with respect to such moneys.

                  SECTION 9.4 Return of Moneys Held by Trustee and Paying  Agent
Unclaimed for Two Years. Any moneys deposited with or paid to the Trustee or any
Paying Agent for the payment of the principal of or premium, if any, or interest
on any Security and not applied but remaining  unclaimed for two years after the
date upon which such  principal,  premium or interest  shall have become due and
payable  shall,  upon the  written  request of the  Issuer and unless  otherwise
required by mandatory provisions of applicable escheat or abandoned or unclaimed
property law, be repaid to the Issuer by the Trustee or such Paying  Agent,  and
the Holder of the  Securities  shall,  unless  otherwise  required by  mandatory
provisions  of  applicable  escheat or  abandoned or  unclaimed  property  laws,
thereafter  look only to the Issuer  for any  payment  which such  Holder may be
entitled to collect,  and all  liability of the Trustee or any Paying Agent with
respect to such  moneys  shall  thereupon  cease;  provided,  however,  that the
Trustee or such Paying Agent,  before being  required to make any such repayment
with respect to moneys deposited with it for any payment,  shall, at the expense
of the Issuer,  mail by first-class  mail to Holders of such Securities at their
addresses as they shall appear on the Security  register notice that such moneys
remain and that, after a date specified therein, which shall not be less than 30
days from the date of such  mailing,  any  unclaimed  balance of such money then
remaining will be repaid to the Issuer upon Issuer Order.

                  SECTION 9.5 Indemnity  for U.S.  Government  Obligations.  The
Issuer shall pay and indemnify the Trustee  against any tax, fee or other charge
imposed  on or  assessed  against  the  U.S.  Government  Obligations  deposited
pursuant to Section 9.1 or the principal or interest received in respect of such
obligations.

                                      -63-
<PAGE>


                                   ARTICLE TEN

                            MISCELLANEOUS PROVISIONS

                  SECTION 10.1 Partners, Incorporators,  Stockholders,  Officers
and Directors of Issue Exempt from  Individual  Liability.  No recourse under or
upon any obliga tion, covenant or agreement  contained in this Indenture,  or in
any Security,  or because of any indebtedness  evidenced  thereby,  shall be had
against  any  incorporator,  as such,  or  against  any past,  present or future
stockholder,  officer or director,  as such,  of the Issuer or of any partner or
member of the Issuer or of any successor,  either directly or through the Issuer
or any successor,  under any rule of law, statute or constitutional provision or
by the enforcement of any assessment or by any legal or equitable  proceeding or
otherwise,  all such  liability  being  expressly  waived  and  released  by the
acceptance  of the  Securities  by  the  Holders  thereof  and  as  part  of the
consideration for the issue of the Securities.

                  SECTION 10.2  Provisions  of Indenture for the Sole Benefit of
Parties and  Securityholders.  Nothing in this  Indenture or in the  Securities,
expressed or implied,  shall give or be  construed to give to any Person,  other
than the parties hereto and their  successors and the Holders of the Securities,
any legal or equitable right,  remedy or claim under this Indenture or under any
covenant or provision herein contained,  all such covenants and provisions being
for the sole benefit of the parties hereto and their  successors and the Holders
of the Securities.

                  SECTION  10.3  Successors  and  Assigns  of  Issuer  Bound  by
Indenture.  All the  covenants,  stipulations,  promises and  agreements in this
Indenture  contained by or on behalf of the Issuer shall bind its successors and
assigns, whether so expressed or not.

                  SECTION  10.4  Notices  and  Demands  on Issuer,  Trustee  and
Securityholders.  Any notice or demand which by any provision of this  Indenture
is required or  permitted to be given or served by the Trustee or by the Holders
of

                                      -64-
<PAGE>

Securities to or on the Issuer may be given or served by being deposited postage
prepaid,  first-class  mail (except as otherwise  specifically  provided herein)
addressed  (until another  address of the Issuer is filed by the Issuer with the
Trustee) to American Tower Corporation, 116 Huntington Avenue, Boston, MA 02116,
Attention: Chief Financial Officer and Secretary. Any notice, direction, request
or demand by the Issuer or any  Securityholder  to or upon the Trustee  shall be
deemed to have been  sufficiently  given or made, for all purposes,  if given or
made  at  the  Corporate  Trust  Office,  Attention:   Corporate  Trust  Trustee
Administration Department.

                  Where this  Indenture  provides  for notice to  Holders,  such
notice shall be sufficiently  given (except as otherwise  specifically  provided
herein) if in writing,  and mailed,  first-class postage prepaid, to each Holder
entitled thereto, at his last address as it appears in the Security register. In
any case where  notice to Holders is given by mail,  neither the failure to mail
such notice,  nor any defect in any notice so mailed,  to any particular  Holder
shall affect the sufficiency of such notice with respect to other Holders. Where
this Indenture  provides for notice in any manner,  such notice may be waived in
writing by the Person  entitled to receive such notice,  either  before or after
the event,  and such waiver shall be the  equivalent of such notice.  Waivers of
notice by Holders shall be filed with the Trustee,  but such filing shall not be
a condition  precedent to the validity of any action taken in reliance upon such
waiver.

                  In case, by reason of the suspension of or irregu  larities in
regular mail service, it shall be impracticable to mail notice to the Issuer and
Securityholders  when  such  notice  is  required  to be given  pursuant  to any
provision of this  Indenture,  then any manner of giving such notice as shall be
satisfactory  to the Trustee  shall be deemed to be a sufficient  giving of such
notice.


                                      -65-
<PAGE>


                  SECTION 10.5 Officers'  Certificates  and Opinions of Counsel;
Statements to Be Contained Therein. Upon any application or demand by the Issuer
to the Trustee to take any action under any of the provisions of this Indenture,
the Issuer shall  furnish to the Trustee an Officers'  Certificate  stating that
all conditions precedent provided for in this Indenture relating to the proposed
action have been  complied  with and an Opinion of Counsel  stating  that in the
opinion of such counsel all such  conditions  precedent have been complied with,
except  that in the case of any  such  application  or  demand  as to which  the
furnishing of such documents is  specifically  required by any provision of this
Indenture  relating to such  particular  application  or demand,  no  additional
certificate or opinion need be furnished.

                  Each certificate or opinion provided for in this Indenture and
delivered to the Trustee with respect to compliance with a condition or covenant
provided for in this  Indenture  shall  include (a) a statement  that the person
making such  certificate  or opinion has read such covenant or condition,  (b) a
brief statement as to the nature and scope of the  examination or  investigation
upon the  statements or opinions  contained in such  certificate  or opinion are
based,  (c) a statement  that,  in the opinion of such person,  he has made such
examination  or  investigation  as is  necessary  to enable  him to  express  an
informed  opinion as to  whether  or not such  covenant  or  condition  has been
complied  with, and (d) a statement as to whether or not, in the opinion of such
person, such condition or covenant has been complied with.

                  Any  certificate,  statement  or  opinion of an officer of the
Issuer may be based, insofar as it relates to legal matters,  upon a certificate
or opinion of or represen tations by counsel, unless such officer knows that the
certificate or opinion or representations with respect to the matters upon which
his  certificate,  statement or opinion may be based as aforesaid are erroneous,
or in the exercise of reasonable  care should know that the same are  erroneous.
Any  certificate,  statement  or opinion of counsel may be based,  insofar as it
relates  to  factual  matters,  information  with  respect  to  which  is in the
possession  of the  Issuer,  upon the  certificate,  statement  or opinion of or
representa-

                                      -66-
<PAGE>

tions by an officer or officers of the Issuer,  unless such  counsel  knows that
the  certificate,  statement or opinion or  representations  with respect to the
matters  upon  which  his  certificate,  statement  or  opinion  may be based as
aforesaid are erroneous,  or in the exercise of reasonable care should know that
the same are erroneous.

                  Any  certificate,  statement  or  opinion of an officer of the
Issuer or of counsel may be based,  insofar as it relates to accounting matters,
upon a certificate or opinion of or  representations by an accountant or firm of
accountants in the employ of the Issuer,  unless such officer or counsel, as the
case may be,  knows that the  certificate  or opinion  or  representations  with
respect to the  accounting  matters  upon which his  certificate,  statement  or
opinion  may  be  based  as  aforesaid  are  erroneous,  or in the  exercise  of
reasonable care should know that the same are erroneous.

                  Any certificate or opinion of any  independent  firm of public
accountants  filed with the Trustee shall contain a statement  that such firm is
independent.

                  SECTION  10.6  Payments  Due on  Saturdays,  Sundays and Legal
Holidays.  If the date of maturity of interest on or principal of the Securities
or the date fixed for redemp tion or  repayment of any Security or the last date
on which a Holder of Securities has a right to convert his Securities  shall not
be a Business Day, then  (notwithstanding  any other provision of this Indenture
or of the  Securities)  payment of interest or  principal or  conversion  of the
Securities need not be made on such date, but may be made on the next succeeding
Business  Day with the same force and effect as if made on the date of  maturity
or the  date  fixed  for  redemption  or  repayment  or on  such  last  day  for
conversion, and no interest shall accrue for the period after such date.

                  SECTION 10.7 Conflict with TIA. Whether or not qualified under
the TIA,  this  Indenture  shall be  interpreted  as though it were so qualified
including provisions required by the TIA or provisions deemed included except as
varied by this Indenture. If any provision hereof limits, qualifies or conflicts
with a provision  of the TIA that is required

                                      -67-
<PAGE>

under the TIA to be a part of and govern this  Indenture,  the latter  provision
shall  control.  If any  provision  of this  Indenture  modifies or excludes any
provision of the TIA that may be so modified or excluded,  the latter  provision
shall be deemed to apply to this Indenture as so modified or to be excluded,  as
the case may be.

                  SECTION 10.8  Communications  by Holders  with Other  Holders.
Securityholders may communicate pursuant to Section 312(b) of the TIA with other
Holders with respect to their rights under this Indenture or the Securities. The
Issuer,  the  Trustee,  the  Registrar  and any  other  person  shall  have  the
protection of Section 312(c) of the TIA.

                  SECTION 10.9 Issuer to Furnish  Trustee Names and Addresses of
Holders. The Issuer will furnish or cause to be furnished to the Trustee:

                  (a) semiannually,  not later than February 15 and August 15 in
         each year, a list, in such form as the Trustee may reasonably  require,
         of the names and addresses of the Securityholders as of a date not more
         than 15 days prior to the delivery thereof, and

                  (b) at such other times as the Trustee may request in writing,
         within 30 days after the receipt by the Issuer of any such  request,  a
         list of  similar  form and  content  as of a date not more than 15 days
         prior to the time such list is furnished;

excluding from any such list names and addresses  received by the Trustee in the
capacity of Registrar.

                  SECTION 10.10 New York Law to Govern.  This Indenture and each
Security  shall be  deemed to be a  contract  under the laws of the State of New
York,  and for all purposes  shall be construed in  accordance  with the laws of
said State, without regard to principles of conflicts of
laws.

                  SECTION 10.11 Counterparts.  This Indenture may be executed in
any  number  of  counterparts,  each of  which


                                      -68-
<PAGE>

shall be an original;  but such counterparts  shall together  constitute but one
and the same instrument.

                  SECTION  10.12  Effect of  Headings.  The  Article and Section
headings herein and the Table of Contents are for convenience only and shall not
affect the construction hereof.


                                 ARTICLE ELEVEN

                            REDEMPTION OF SECURITIES

                  SECTION 11.1 Right of Optional Redemption;  Prices. The Issuer
at its option may, on and after  October 22,  2003,  redeem all, or from time to
time any part of, the Securities upon payment of the optional  Redemption Prices
set forth in the form of Security  attached as Exhibit A hereto,  together  with
accrued interest to the date fixed for redemption.

                  SECTION 11.2 Notice of Redemption; Partial Redemptions. Notice
of  redemption to the Holders of Securities to be redeemed as a whole or in part
shall be given by mailing notice of such redemption by first-class mail, postage
prepaid,  at least 20 days and not more than 60 days prior to the date fixed for
redemption to such Holders of  Securities at their last  addresses as they shall
appear upon the registry books.  Any notice which is mailed in the manner herein
provided shall be conclusively  presumed to have been duly given, whether or not
the Holder receives the notice. Failure to give notice by mail, or any defect in
the notice to the Holder of any Security designated for redemption as a whole or
in part,  shall not affect the validity of the proceedings for the redemption of
any other Security.

                  The notice of redemption to each such Holder shall specify the
principal  amount of each Security held by such Holder to be redeemed,  the date
fixed for redemption (the "Redemption Date"), the CUSIP numbers,  the applicable
Redemption Price, the place or places of payment, that

                                      -69-
<PAGE>

payment will be made upon  presentation and surrender of such  Securities,  that
interest  accrued to the date fixed for redemption  will be paid as specified in
said notice and that on and after said date interest and Original Issue Discount
thereon or on the  portions  thereof to be  redeemed  will cease to accrue,  and
shall also specify the Conversion Price then in effect and the date on which the
right to convert such  Securities  or the portions  thereof to be redeemed  will
expire.  In case any  Security  is to be  redeemed  in part  only the  notice of
redemption  shall  state the  portion  of the  principal  amount  thereof  to be
redeemed and shall state that on and after the date fixed for  redemption,  upon
surrender of such  Security,  a new Security or Securities  in principal  amount
equal to the unredeemed portion thereof will be issued.

                  The notice of  redemption  of Securities to be redeemed at the
option of the Issuer shall be given by the Issuer or, at the  Issuer's  request,
by the Trustee in the name and at the expense of the Issuer.

                  At  least  one  Business  Day  prior  to the  Redemption  Date
specified in the notice of  redemption  given as provided in this  Section,  the
Issuer will deposit  with the Trustee or with one or more Paying  Agents (or, if
the Issuer is acting as its own Paying Agent,  set aside,  segregate and hold in
trust as  provided  in Section  2.3) an amount of money suffi cient to redeem on
the  Redemption  Date all the  Securities so called for  redemption  (other than
those theretofore  surrendered for conversion pursuant to Article Twelve) at the
appropriate  Redemption  Price (which includes accrued Original Issue Discount),
together with accrued  interest to and including the date fixed for  redemption.
If any Security called for redemption is converted  pursuant  hereto,  any money
deposited  with the  Trustee or any Paying  Agent or so  segregated  and held in
trust for the  redemption  of such  Security  shall be paid to the  Issuer  upon
Issuer  Order,  or, if then held by the Issuer,  shall be  discharged  from such
trust.  If less than all the  outstanding  Securities  are to be  redeemed,  the
Issuer will  deliver to the Trustee at least 10 days prior to the date of making
of the notice of

                                      -70-
<PAGE>

redemption an Officers'  Certificate  stating the aggregate  principal amount of
Securities to be redeemed.

                  If  less  than  all the  Securities  are to be  redeemed,  the
Trustee shall select,  by lot, pro rata or by such other manner as it shall deem
appropriate and fair,  Securities to be redeemed in whole or in part. Securities
may  be  redeemed  in  part  in  multiples  equal  to  the  minimum   authorized
denomination for Securities or any multiple thereof.  The Trustee shall promptly
notify the Issuer in writing of the Securities  selected for redemption  and, in
the case of any Securities selected for partial redemption, the principal amount
thereof to be redeemed.  For all purposes of this Indenture,  unless the context
otherwise  requires,  all  provisions  relating to the  redemption of Securities
shall  relate,  in the case of any Security  redeemed or to be redeemed  only in
part, to the portion of the principal  amount of such Security which has been or
is  to  be  redeemed.  If  any  Security  selected  for  partial  redemption  is
surrendered for conversion after such selection,  the converted  portion of such
Security  shall be  deemed  (so far as may be) to be the  portion  selected  for
redemption. Upon any redemption of less than all the Securities, for purposes of
the  selection  for  redemption,  the  Issuer  and  the  Trustee  may  treat  as
Outstanding  Securities  surrendered for conversion during the period of 15 days
next  preceding  the  mailing of a notice of  redemption,  and need not treat as
Outstanding  any  Security  authenticated  and  delivered  during such period in
exchange for the  unconverted  portion of any Security  converted in part during
such period.

                  SECTION 11.3 Payment of Securities  Called for Redemption.  If
notice  of  redemption  has been  given as above  provided,  the  Securities  or
portions of Securities  specified in such notice shall become due and payable on
the date and at the place  stated in such  notice at the  applicable  Redemption
Price,  together  with  interest  accrued  to and  including  the date fixed for
redemption,  and on and after said date (unless the Issuer shall  default in the
payment of such  Securities  at the  Redemption  Price,  together  with interest
accrued to said date)  interest and Original Issue

                                      -71-
<PAGE>

Discount on the  Securities or portions of  Securities so called for  redemption
shall cease to accrue and such  Securities  shall cease from and after the close
of  business  on the  Business  Day  immediately  prior  to the date  fixed  for
redemption to be  convertible  pursuant to the  provisions of Article Twelve or,
except as  provided  in  Sections  2.4 and 9.4,  be  entitled  to any benefit or
security under this  Indenture,  and the Holders  thereof shall have no right in
respect of such Securities except the right to receive the applicable Redemption
Price  thereof  and  unpaid  interest  to  and  including  the  date  fixed  for
redemption.  On  presentation  and  surrender of such  Securities  at a place of
payment  specified in said notice,  said  Securities or the  specified  portions
thereof  shall be paid and redeemed by the Issuer at the  applicable  Redemption
Price,  together with interest  accrued  thereon to and including the date fixed
for redemption,  provided that any payment of interest  becoming due on or prior
to the date  fixed  for  redemption  shall be  payable  to the  Holders  of such
Securities  registered as such on the relevant  record date subject to the terms
and provisions of Section 2.11 hereof.

                  If any  Security  called for  redemption  shall not be so paid
upon surrender thereof for redemption,  the principal shall,  until paid or duly
provided for,  bear  interest from the date fixed for  redemption at the rate of
interest  specified in such Security (giving effect to accrual of Original Issue
Discount) and such Security shall remain convertible  pursuant to the provisions
of Article  Twelve until the principal of such Security  shall have been paid or
duly provided for.

                  Upon  presentation of any Security  redeemed in part only, the
Issuer shall execute and the Trustee shall authenticate and deliver to or on the
order of the Holder  thereof,  at the expense of the Issuer,  a new  Security or
Securities,  of  authorized  denominations,  in  principal  amount  equal to the
unredeemed portion of the Security so presented.

                  SECTION 11.4 Exclusion of Certain  Securities from Eligibility
for Selection for Redemption.  Securities shall

                                      -72-
<PAGE>

be excluded from eligibility for selection for redemption if they are identified
by  registration  and  certificate  number in a written  statement  signed by an
Officer of the Issuer and delivered to the Trustee at least 40 days prior to the
last date on which  notice of  redemption  may be given as being owned of record
and beneficially by, and not pledged or hypothecated by either (a) the Issuer or
(b) an entity specifically  identified in such Officers' Certificate directly or
indirectly  controlling  or  controlled  by or under  direct or indirect  common
control with the Issuer.

                  SECTION 11.5 Conversion Arrangement on Call for Redemption. In
connection with any redemption of the Securities, the Issuer may arrange for the
purchase and  conversion  of any  Securities  by an  agreement  with one or more
investment  bankers or other  purchasers  (the  "Purchasers")  to purchase  such
Securities by paying to the Trustee in trust for the Holders, on or before 11:00
a.m., Eastern Standard Time, on the Redemption Date, an amount not less than the
applicable  Redemption  Price,  together with interest accrued and unpaid to the
Redemption  Date, of such Securities.  Notwithstanding  anything to the contrary
contained in this Article,  the  obligation of the Issuer to pay the  Redemption
Price,  together with interest  accrued and unpaid to the Redemption Date, shall
be deemed to be satisfied and discharged to the extent such amount is so paid by
such Purchasers.  If such an agreement is entered into (a copy of which shall be
filed with the Trustee prior to the close of business on the second Business Day

immediately  prior to the Redemption Date), any Securities called for redemption
that are not duly  surrendered for conversion by the Holders thereof may, at the
option of the Issuer,  be deemed,  to the fullest  extent  permitted by law, and
consistent with any agreement or agreements with such Purchasers, to be acquired
by such  Purchasers  from such  Holders  and  (notwithstanding  anything  to the
contrary  contained  in  this  Article)   surrendered  by  such  Purchasers  for
conversion,  all  as of  immediately  prior  to the  close  of  business  on the
Redemption Date (and the right to convert any such Securities  shall be extended
through such time), subject to payment of the above amount as aforesaid.  At the
written direction of the Issuer,  the Trustee shall hold and

                                      -73-
<PAGE>

dispose of any such  amount paid to it by the  Purchasers  to the Holders in the
same  manner  as it  would  monies  deposited  with  it by the  Issuer  for  the
redemption of  Securities.  Without the  Trustee's  prior  written  consent,  no
arrangement  between  the  Issuer  and  such  Purchasers  for the  purchase  and
conversion  of any  Securities  shall  increase or  otherwise  affect any of the
powers,  duties,  responsibilities or obligations of the Trustee as set forth in
this Indenture, and the Issuer agrees to indemnify the Trustee from, and hold it
harmless against, any loss, liability or expense arising out of or in connection
with any such  arrangement  for the purchase and  conversion  of any  Securities
between  the  Issuer  and such  Purchasers,  including  the costs and  expenses,
including  reasonable legal fees,  incurred by the Trustee in the defense of any
claim  or  liability  arising  out of or in  connection  with  the  exercise  or
performance of any of its powers, duties,  responsibilities or obligations under
this Indenture.


                                 ARTICLE TWELVE

                            CONVERSION OF SECURITIES

                  SECTION 12.1 Conversion Privilege.  A Holder of a Security may
convert it into Class A Common Stock of the Issuer at any time prior to maturity
at the  conversion  price  then in  effect,  except  that,  with  respect to any
Security  called for redemption,  such  conversion  right shall terminate at the
close of business on the Business Day immediately preceding the Redemption Date,
Change in Control  Repurchase  Date or Repurchase  Date (unless the Issuer shall
default in making the  redemption or repurchase  payment then due, in which case
the conversion  right shall  terminate on the date such default is cured and, if
applicable,  the  provisions of Section  13.2(d) are  satisfied).  The number of
shares  of Class A Common  Stock  issuable  upon  conversion  of a  Security  is
determined as follows:  divide the Issue Price to be converted by the Conversion
Price in  effect on the Date of  Conversion;  round  the  result to the  nearest
1/100th of a share.

                                      -74-
<PAGE>

                  The initial Conversion Price is stated in the fourth paragraph
of the reverse of the  Securities  and is subject to  adjustment  as provided in
this Article.

                  A Holder may  convert a portion of a Security  equal to $1,000
principal amount or any integral multiple thereof.  Provisions of this Indenture
that apply to  conversion  of all of a Security  also apply to  conversion  of a
portion of it.

                  SECTION 12.2  Exercise of  Conversion  Privilege.  In order to
exercise the  conversion  privilege,  the Holder of any Security to be converted
shall  surrender  such Security to the Issuer at any time during usual  business
hours at its office or agency  maintained  for the  purpose as  provided in this
Indenture,  accompanied by a fully executed written notice, in substantially the
form set forth on the reverse of the Security, that the Holder elects to convert
such Security or a stated portion thereof constituting a multiple of the minimum
authorized  denomination  thereof,  and,  if such  Security is  surrendered  for
conversion  during the period  between  the close of business on any record date
for such  Security and the opening of business on the related  interest  payment
date (unless such Security shall have been called for redemption on a Redemption
Date or Change in Control Repurchase Date within such period or on such interest
payment  date),  accompanied  also by payment of an amount equal to the interest
payable on such interest  payment date on the portion of the principal amount of
the Security being  surrendered  for  conversion.  A Holder of any Security on a
record date for such Security who converts such Security on the related interest
payment  date will  receive  the  interest  payable on such  Security,  and such
converting  Holder  need  not  include  a  payment  for any such  interest  upon
surrender of such Security for conversion. Such notice shall also state the name
or names (with address) in which the certificate or  certificates  for shares of
Class A Common  Stock shall be issued.  Securities  surrendered  for  conversion
shall (if so required by the Issuer or the  Trustee) be duly  endorsed by, or be
accompanied  by  a  written  instrument  or  instruments  of  transfer  in  form
satisfactory  to the Issuer and the Trustee duly  executed by, the Holder or his
attorney duly authorized in writing. As promptly as

                                      -75-
<PAGE>

practicable  after the receipt of such notice and the surrender of such Security
as aforesaid, the Issuer shall, subject to the provisions of Section 12.7, issue
and deliver at such office or agency to such Holder,  or on his written order, a
certificate  or  certificates  for the  number of full  shares of Class A Common
Stock  issuable  on  such  conversion  of  Securities  in  accordance  with  the
provisions  of this Article and cash, as provided in Section 12.3, in respect of
any fraction of a share of Class A Common  Stock  otherwise  issuable  upon such
conversion.  Such conversion  shall be deemed to have been effected  immediately
prior  to the  close  of  business  on the  date  (herein  called  the  "Date of
Conversion")  on which such  notice  shall have been  received by the Issuer and
such  Security  shall  have been  surrendered  as  aforesaid,  and the Person or
Persons in whose name or names any  certificate  or  certificates  for shares of
Class A Common Stock shall be issuable upon such  conversion  shall be deemed to
have  become on the Date of  Conversion  the  holder or holders of record of the
shares represented thereby;  provided,  however,  that any such surrender on any
date  when  the  stock  transfer  books of the  Issuer  shall  be  closed  shall
constitute  the  person or persons  in whose  name or names the  certificate  or
certificates  for such  shares are to be issued as the  recordholder  or holders
thereof for all purposes at the opening of business on the next  succeeding  day
on  which  such  stock  transfer  books  are  open  but  such  conversion  shall
nevertheless  be at the  Conversion  Price in effect at the close of business on
the date when such Security shall have been so  surrendered  with the conversion
notice.  In the case of  conversion  of a  portion,  but  less  than  all,  of a
Security,  the Issuer shall  execute,  and the Trustee  shall  authenticate  and
deliver to the Holder  thereof,  at the  expense of the  Issuer,  a Security  or
Securities in the aggregate  principal amount of the unconverted  portion of the
Security surrendered.  Except as otherwise expressly provided in this Indenture,
no payment or adjustment  shall be made for interest or Original  Issue Discount
accrued on any  Security  (or portion  thereof)  converted  or for  dividends or
distributions  on any  Class  A  Common  Stock  issued  upon  conversion  of any
Security;  provided,  however,  that in the  case of any  Securities  which  are
converted  after the close of business on a relevant record date and on or prior
to the

                                      -76-
<PAGE>

next succeeding  interest  payment date,  installments of interest which are due
and payable on the next  succeeding  interest  payment  date shall be payable on
such interest payment date notwithstanding such conversion (unless such Security
shall have been called for redemption on a Redemption  Date or Change in Control
Repurchase Date after the close of business on such record date and prior to the
opening of business on such interest payment date) and such interest (whether or
not  punctually  paid or duly  provided for) shall be paid to the Holder of such
Securities  registered  as such at the close of business on the relevant  record
date  according  to their terms.  The  Issuer's  delivery of the fixed number of
shares of Class A Common Stock into which the Securities are convertible will be
deemed  to  satisfy  the  Issuer's  obligation  to pay the  principal  amount at
maturity of the Securities and all accrued  interest and Original Issue Discount
that has not previously been (or is not simultaneously  being) paid. The Class A
Common  Stock is treated as issued  first in  payment  of accrued  interest  and
Original Issue Discount and then in payment of principal.

                  SECTION 12.3 Fractional Shares. Except as pro vided below, the
Issuer will not issue fractional  shares of Class A Common Stock upon conversion
of  Securities.  In  lieu  thereof,  in the  sole  discretion  of the  Board  of
Directors, either (a) such fractional interest will be rounded up to the nearest
full  share,  or (b) an  appropriate  amount will be paid in cash by the Issuer,
unless payment in cash is prohibited by the terms of the Issuer's  indebtedness,
in which case fractional shares may be issued. If the Issuer shall deliver cash,
such cash shall be in the amount of the fair market value (as  determined by the
Board of Directors) of such fractional interest. If more than one Security shall
be surrendered for conversion at one time by the same Holder, the number of full
shares  issuable upon  conversion  thereof shall be computed on the basis of the
aggregate  number  of  Securities,  or  the  specified  portions  thereof  to be
converted, so surrendered.

                  SECTION 12.4  Adjustment of Conversion  Price.  The Conversion
Price shall be subject to adjustment from time to time as follows:

                                      -77-
<PAGE>

                  (a) In case the  Issuer  shall  (1) pay a  dividend  or make a
         distribution on Class A Common Stock in shares of Class A Common Stock,
         (2)  subdivide  its  outstanding  shares of Class A Common Stock into a
         greater number of shares or (3) combine its outstanding shares of Class
         A Common Stock into a smaller number of shares, the Conversion Price in
         effect  immediately  prior to such action shall be adjusted as provided
         below so that the Holder of any  Security  thereafter  surrendered  for
         conversion shall be entitled to receive the number of shares of Class A
         Common Stock which he would have been  entitled to receive  immediately
         following  such action had such  Security  been  converted  immediately
         prior thereto. An adjustment made pursuant to this subsection (a) shall
         become  effective  immedi ately,  except as provided in subsection  (e)
         below,  after the record date in the case of a dividend or distribution
         and shall become effective  immediately after the effective date in the
         case of a subdivision or combination.

                  (b) In case the Issuer shall issue rights, warrants or options
         to all  holders  of Class A Common  Stock  entitling  them for a period
         expiring within 45 days after the record date therefor to subscribe for
         or  purchase  shares of Class A Common  Stock at a price per share less
         than the  current  market  price per share (as  determined  pursuant to
         subsection  (d) below) of the Class A Common  Stock on the record  date
         mentioned  below,  the  Conversion  Price shall be adjusted to a price,
         computed  to the nearest  cent,  so that the same shall equal the price
         determined by multiplying:

                           (1) the Conversion Price in effect  immediately prior
                  to the date of issuance of such rights,  warrants or option by
                  a fraction, of which

                           (2) the  numerator  shall be (A) the number of shares
                  of Class A Common Stock outstanding on the date of issuance of
                  such  rights,  warrants or options  immediately  prior to such
                  issuance,  plus (B) the number of shares  which the  aggregate

                                      -78-
<PAGE>

                  offering  price of the total  number of shares so offered  for
                  subscription or purchase would purchase at such current market
                  price  (determined by multiplying  such total number of shares
                  by the exercise price of such rights,  warrants or options and
                  dividing  the  product  so  obtained  by such  current  market
                  price), and of which

                           (3) the denominator shall be (A) the number of shares
                  of Class A Common Stock outstanding on the date of issuance of
                  such rights,  warrants or options,  immediately  prior to such
                  issuance,  plus (B) the number of additional shares of Class A
                  Common  Stock  which  are  so  offered  for   subscription  or
                  purchase.

                  Such adjustment shall become effective immedi ately, except as
         provided  in  subsection  (e)  below,  after  the  record  date for the
         determination of Holders  entitled to receive such rights,  warrants or
         options.

                  (c) In case the  Issuer  shall  distribute  to all  holders of
         Class A Common  Stock  evidences  of  indebtedness,  equity  securities
         (including  equity interests in the Issuer's  Subsidiaries)  other than
         Class A Common Stock or other assets  (other than cash  dividends),  or
         shall  distribute  to all  holders  of  Class A  Common  Stock  rights,
         warrants  or options  to  subscribe  to  securities  (other  than those
         referred to in subsection (b) above and dividends and  distributions in
         connection  with the  liquidation,  dissolution  or  winding  up of the
         Issuer),  then in each such case the Conversion Price shall be adjusted
         so that the same shall equal the price  determined by  multiplying  the
         Conversion  Price  in  effect  immediately  prior  to the  date of such
         distribution  by a fraction of which the numerator shall be the current
         market price per share (determined as provided in subsection (d) below)
         of the Class A Common Stock on the record date mentioned below less the
         then fair market value (as determined by the Board of Directors,  whose
         determination  shall be conclusive  evidence of such fair market value,
         and


                                      -79-
<PAGE>

         described in a Board  Resolution filed with the Trustee) of the portion
         of the assets,  evidences  of  indebtedness  and equity  securities  so
         distributed  or  of  such  subscription  rights,  warrants  or  options
         applicable  to one  share  of Class A Common  Stock,  and of which  the
         denominator shall be such current market price per share of the Class A
         Common Stock.  For the purposes of this subsection (c), in the event of
         a  distribution  of shares of capital stock or other  securities of any
         Subsidiary  as a dividend on shares of Class A Common  Stock,  the then
         fair  market  value of the shares of other  securities  so  distributed
         shall be deemed to be the market value  (determined as provided  above)
         of such  shares  or other  securities.  Such  adjustment  shall  become
         effective  immediately,  except as  provided in  subsection  (e) below,
         after the record date for the determination of stockholders entitled to
         receive such distribution.

                  (d) For the purpose of any computation  under  subsections (b)
         and (c) above,  the  current  market  price per share of Class A Common
         Stock on any date  shall be deemed to be the  average  of the Last Sale
         Prices  of a share  of Class A Common  Stock  for the five  consecutive
         Trading  Days  commencing  not more than 20 Trading  Days  before,  and
         ending not later than, the earlier of the date in question and the date
         before  the "ex" date with  respect  to the  issuance  or  distribution
         requiring such  computation.  For purposes of this paragraph,  the term
         "'ex' date",  when used with  respect to any issuance or  distribution,
         means the first date on which the Class A Common Stock  trades  regular
         way on the principal national  securities exchange on which the Class A
         Common  Stock is listed or  admitted to trading (or if not so listed or
         admitted  on NASDAQ or a  similar  organization  if NASDAQ is no longer
         reporting  trading  information)  without  the  right to  receive  such
         issuance or distribution.

                  (e) In any case in which this  Section  shall  require that an
         adjustment be made immediately follow ing a record date, the Issuer may
         elect to defer the

                                      -80-
<PAGE>

         effectiveness  of such  adjustment  (but in no event until a date later
         than the effective  time of the event giving rise to such  adjustment),
         in which case the Issuer shall, with respect to any Security  converted
         after such  record date and before  such  adjustment  shall have become
         effective (i) defer making any cash payment pursuant to Section 12.3 or
         issuing to the Holder of such  Security the number of shares of Class A
         Common Stock and other capital  stock of the Issuer  issuable upon such
         conversion  in excess of the  number of shares of Class A Common  Stock
         and other capital stock of the Issuer  issuable  thereupon  only on the
         basis of the Conversion  Price prior to adjustment,  and (ii) not later
         than five  Business  Days  after  such  adjustment  shall  have  become
         effective,  pay to such Holder the appropriate cash payment pursuant to
         Section 12.3 and issue to such Holder the additional  shares of Class A
         Common  Stock and other  capital  stock of the Issuer  issuable on such
         conversion.

                  (f) No adjustment in the Conversion Price shall be required if
         Securityholders  are to participate  in the  transaction on a basis and
         with  notice  that the  Board of  Directors  determines  to be fair and
         appropri ate in light of the basis and notice on which holders of Class
         A  Common  Stock  participate  in  the  transaction.  In  addition,  no
         adjustment  in the  Conversion  Price  shall be  required  unless  such
         adjustment  would require an increase or decrease of at least 1% in the
         Conversion Price; provided that any adjustments which by reason of this
         subsection (f) are not required to be made shall be carried forward and
         taken into account in any subsequent adjustment. All calculations under
         this  Article  shall  be made  to the  nearest  cent or to the  nearest
         one-hundredth of a share, as the case may be.

                  (g)  Whenever  the  Conversion  Price is  adjusted  as  herein
         provided,  the Issuer shall promptly (i) file with the Trustee and each
         conversion agent an Officers'  Certificate setting forth the Conversion
         Price after such adjustment and setting forth in reasonable  detail the
         facts  requiring  such  adjustment  and the

                                      -81-
<PAGE>

         calculations on which the adjustment is based,  which certificate shall
         be conclusive  evidence of the correctness of such adjustment and which
         shall be made available by the Trustee to the Holders of Securities for
         inspection  thereof,  (ii)  mail or cause to be mailed a notice of such
         adjustment, setting forth the adjusted Conversion Price and the date on
         which such adjustment  became or becomes  effective,  to each Holder of
         Securities at his address as the same appears on the registry  books of
         the Issuer.

                  To the extent  permitted  by law, the Issuer from time to time
may  reduce  the  Conversion  Price by any  amount for any period of at least 20
days, if the Board of Directors  has made a  determination  that such  reduction
would be in the best  interests  of the  Issuer,  which  determination  shall be
conclusive.  In such case, the Issuer shall give at least 15 days' notice of the
reduction. In addition, at its option, the Issuer may make such reduction in the
Conversion  Price as the Board of Directors deems advisable to avoid or diminish
any income tax to holders of Class A Common Stock resulting from any dividend or
distribution  of stock (or rights to acquire stock) or from any event treated as
such for income tax purposes.

                  SECTION 12.5  Continuation of Conversion  Privilege in Case of
Reclassification,  Reorganization,  Change,  Merger,  Consolidation  or  Sale of
Assets.  If any transaction shall occur,  including  without  limitation (i) any
recapitalization  or  reclassification  of shares of Class A Common Stock (other
than a change in par value,  or from par value to no par  value,  or from no par
value to par value,  or as a result of a subdivision or combination of the Class
A Common  Stock),  (ii) any  consolidation  or merger of the Issuer with or into
another  person or any merger of another  person  into the Issuer  (other than a
consolidation or merger that does not result in a reclassification,  conversion,
exchange or cancellation of Class A Common Stock), (iii) any sale or transfer of
all or  substantially  all of the assets of the Issuer,  or (iv) any  compulsory
share  exchange,  pursuant to any of which holders of Class A Common Stock shall
be  entitled  to  receive  other  securities,   cash  or  other

                                      -82-
<PAGE>

property,  then  appropriate  provision shall be made so that the Holder of each
Security  then  Outstanding  shall have the right  thereafter  to  convert  such
Security only into the kind and amount of the securities, cash or other property
that would have been  receivable upon such  recapitalization,  reclassification,
consolidation,  merger,  sale,  transfer  or share  exchange  by a holder of the
number  of shares  of Class A Common  Stock  issuable  upon  conversion  of such
Security   immediately   prior  to  such   recapitalization,   reclassification,
consolidation,  merger, sale, transfer or share exchange, after giving effect to
any adjustment in the conversion  price in accordance with this  Indenture.  The
company  formed by such  consolidation  or  resulting  from such  merger or that
acquires such assets or that acquires the Issuer's  shares,  as the case may be,
shall make provisions in its certificate of incorporation  or other  constituent
document to establish such right.  Such  certificate of  incorporation  or other
constituent  document shall provide for adjustments  that, for events subsequent
to the effective date of such certificate of incorporation or other  constituent
documents,  shall be as nearly  equivalent as may be practicable to the relevant
adjustments provided for in Section 12.4 and in this Section.

                  SECTION 12.6  Notice of Certain Events.  In case:

                  (a)  the  issuer  shall  declare  a  dividend  (or  any  other
         distribution)  payable to the  holders of Class A Common  Stock  (other
         than cash dividends and dividends payable in Class A Common Stock); or

                  (b) the Issuer shall  authorize the granting to the holders of
         Class A Common Stock of rights, warrants or options to subscribe for or
         purchase  any  shares  of stock of any  class or of any  other  rights,
         warrants or options; or

                  (c) the Issuer shall authorize any reclassifica tion or change
         of the Class A Common Stock (other than a subdivision or combination of
         its  outstanding  shares  of  Class A Common  Stock or a change  in par
         value,  or from par value to no par value,  or from no par value to


                                      -83-
<PAGE>

         par  value),  or any  consolidation  or merger to which the Issuer is a
         party and for which  approval  of any stock  holders  of the  Issuer is
         required,  or the sale or  conveyance of all or  substantially  all the
         property or business of the Issuer; or

                  (d) there  shall be  proposed  any  voluntary  or  involuntary
         dissolution, liquidation or winding-up of the Issuer;

then,  the Issuer shall cause to be filed with the  Trustee,  and, if other than
the Corporate  Trust Office of the Trustee,  at the office or agency  maintained
for the purpose of conversion of the  Securities as provided in Section 2.3, and
shall  cause to be mailed to each  Holder of  Securities,  at his  address as it
shall appear on the registry books of the Issuer, as promptly as possible but in
any event at least 20 days before the date hereinafter specified (or the earlier
of the dates  hereinafter  specified,  in the  event  that more than one date is
specified),  a notice  stating  the date on which (1) a record is expected to be
taken for the  purpose  of such  dividend,  distribution,  rights,  warrants  or
options,  or if a record is not to be taken, the date as of which the holders of
Class A Common  Stock of record to be entitled to such  dividend,  distribution,
rights or warrants are to be determined,  or (2) such reclassification,  change,
consolidation,  merger, sale, transfer, conveyance, dissolution,  liquidation or
winding-up is expected to become  effective and the date, if any is to be fixed,
as of which it is expected  that holders of Class A Common Stock of record shall
be entitled to exchange  their shares of Class A Common Stock for  securities or
other property deliverable upon such  reclassification,  change,  consolidation,
merger, sale, transfer, conveyance, dissolution, liquidation or winding-up.

                  SECTION 12.7 Taxes on Conversion. The issuance and delivery of
certificates  for shares of Class A Common  Stock on  conversion  of  Securities
shall be made without  charge to the  converting  Holder of Securities  for such
certificates  or for any  documentary,  stamp or similar issue or transfer taxes
payable to the United States of America or

                                      -84-
<PAGE>

any political subdivision or taxing authority thereof in respect of the issuance
or delivery of such certificates;  provided,  however, that the Issuer shall not
be  required  to pay any tax which may be payable  in  respect  of any  transfer
involved in the issuance of certificates for shares of Class A Common Stock, and
no such issue or delivery  shall be made unless and until the Person  requesting
such issue or delivery  has paid to the Issuer the amount of any such tax or has
established, to the satisfaction of the Issuer, that such tax has been paid.

                  SECTION  12.8  Issuer to  Provide  Class A Common  Stock.  The
Issuer  covenants that it will reserve and keep available,  free from preemptive
rights,  out of its  authorized but unissued  shares,  solely for the purpose of
issue upon  conversion of Securities as herein  provided,  sufficient  shares of
Class A Common Stock to provide for the conversion of the  Securities  from time
to time as such Securities are presented for conversion.

                  If any shares of Class A Common  Stock to be reserved  for the
purpose of conversion  of  Securities  hereunder  require  registration  with or
approval  of any  governmental  authority  under any Federal or State law before
such shares may be validly issued or delivered upon conversion,  then the Issuer
covenants that it will in good faith and as expeditiously  as possible  endeavor
to secure such registration or approval, as the case may be; provided,  however,
that  nothing  in  this  Section  shall  be  deemed  to  affect  in any  way the
obligations  of the Issuer to convert  Securities  into Class A Common  Stock as
provided in this Article.

                  Before  taking  any action  which  would  cause an  adjustment
reducing the Conversion  Price below the then par value,  if any, of the Class A
Common  Stock,  the Issuer  will take all  corporate  action  which may,  in the
Opinion of  Counsel,  be  necessary  in order that the  Issuer may  validly  and
legally  issue fully paid and  non-assessable  shares of Class A Common Stock at
such adjusted Conversion Price.

                                      -85-
<PAGE>

                  The Issuer  covenants  that all shares of Class A Common Stock
which  may be issued  upon  conversion  of  Securities  will upon  issue be duly
authorized,  validly issued and fully paid and  non-assessable by the Issuer and
free of  preemptive  rights  and of any lien or adverse  claim and that,  if the
Class A Common  Stock is then  listed on any  national  securities  exchange  or
quoted on NASDAQ,  the shares of Class A Common  Stock  which may be issued upon
conversion of Securities will be similarly  listed or quoted at the time of such
issuance.

                  The Issuer  covenants  that,  upon conversion of Securities as
herein provided, there will be credited to Class A Common Stock par capital from
the  consideration  for which the shares of Class A Common Stock  issuable  upon
such conversion are issued an amount per share of Class A Common Stock so issued
as determined by the Board of Directors, which amount shall not be less than the
amount  required by law and by the Issuer's  certificate  of  incorporation,  as
amended,  as in effect on the date of such conversion.  For the purposes of this
covenant the net  proceeds  received by the Issuer from the issuance and sale of
the Securities  converted,  less any cash conversion,  shall be deemed to be the
amount of  consideration  for which the shares of Class A Common Stock  issuable
upon such conversion are issued.

                  SECTION 12.9 Disclaimer of Responsibility for Certain Matters.
Neither the Trustee nor any  Conversion  Agent or agent of the Trustee  shall at
any time be under any duty or  responsibility  to any  Holder of  Securities  to
determine  whether  any facts exist  which may  require  any  adjustment  of the
Conversion  Price, or with respect to the Officers'  Certificate  referred to in
Section 12.4(g),  or with respect to the nature or extent of any such adjustment
when  made,  or  with  respect  to the  method  employed,  or  herein  or in any
supplemental  indenture provided to be employed, in making the same. Neither the
Trustee  nor any  Conversion  Agent  nor  any  agent  of the  Trustee  shall  be
accountable with respect to the validity,  registration,  listing,  or value (or
the kind or amount) of any shares of Class A Common Stock,  or of any securities
or cash or other property, which may at any time be issued or delivered upon the
conversion of any

                                      -86-
<PAGE>

Security;  and  neither  the  Trustee  nor  any  agent  of the  Trustee  nor any
Conversion  Agent makes any  representation  with respect  thereto.  Neither the
Trustee  nor any  Conversion  Agent  nor  any  agent  of the  Trustee  shall  be
responsible  for any failure of the Issuer to make any cash payment or to issue,
register  the transfer of or deliver any shares of Class A Common Stock or stock
certificates or other  securities or property upon the surrender of any Security
for the purpose of  conversion  or,  subject to Sections  5.1 and 5.2, to comply
with any of the covenants of the Issuer contained in this Article.

                  SECTION  12.10 Return of Funds  Deposited  for  Redemption  of
Converted  Securities.  Any funds which at any time shall have been deposited by
the Issuer or on its behalf with the Trustee or any other  Paying  Agent for the
purpose of paying the  principal  of and interest on any of the  Securities  and
which shall not be required for such purposes  because of the conversion of such
Securities,  as provided in this Article, shall after such conversion,  upon the
written  request of the  Issuer,  be repaid to the Issuer by the Trustee or such
other Paying Agent.


                                ARTICLE THIRTEEN

               RIGHT TO REQUIRE REDEMPTION UPON CHANGE IN CONTROL

         SECTION  13.1 Right to Require  Redemption.  If at any time there shall
occur any Change in Control (as defined  below) of the Issuer,  then each Holder
shall have the right, at such Holder's option,  to require the Issuer to redeem,
and upon the exercise of such right the Issuer shall redeem,  all or any part of
such  Holder's  Securities  that is $1,000 in  principal  amount or any integral
multiple thereof,  on the date (the "Change in Control Repurchase Date") that is
45 days after the date of the Issuer  Notice  (as  defined  below) at a price in
cash equal to the sum of the Issue Price  thereof  plus accrued  Original  Issue
Discount  to the  Repurchase  Date,  and  accrued  and  unpaid  interest  to the
Repurchase Date (the "Change in Control Repurchase Price").


                                      -87-
<PAGE>

         SECTION 13.2 Notices;  Method of Exercising  Redemption Right, etc. (a)
Unless  the  Issuer  shall  have  theretofore  called  for  redemption  all  the
Securities then  Outstanding  pursuant to Article Eleven,  on or before the 30th
day after the  occurrence of a Change in Control,  the Issuer or, at the request
of the  Issuer,  the  Trustee,  shall  forward  to all  holders of record of the
Securities a notice (the  "Issuer  Notice") of the  occurrence  of the Change in
Control and of the redemption right set forth herein arising as a result thereof
in the manner  provided in Section 10.4 hereof.  The Issuer shall also deliver a
copy of the Issuer Notice to the Trustee prior to or promptly  after the mailing
of such Issuer Notice.

                  Each Issuer Notice shall state:

                  (1)      the Change in Control Repurchase Date;

                  (2) the date by which the  Securities  with  respect  to which
         such  right is  being  exercised  and the  irrevocable  written  notice
         referred to in Section 13.2(b) must be delivered to the Trustee;

                  (3) the Change in Control Repurchase Price,  including accrued
         Original Issue Discount and accrued interest, if any;

                  (4) a description of the procedure  which a Holder must follow
         to exercise a  redemption  right  including  a form of the  irrevocable
         written notice referred to in Section 13.2(b); and

                  (5) the Conversion Price then in effect, the date on which the
         right to convert the principal  amount of the Securities to be redeemed
         will  terminate  and the place or places where such  Securities  may be
         surrendered for conversion.

                  No  failure  of the  Issuer to give the  Issuer  Notice or any
defect therein shall limit any Holder's right to exercise a redemption  right or
affect the validity of the proceedings for the redemption of Securities.

                                      -88-
<PAGE>

                  (b) To exercise a redemption  right, a Holder shall deliver to
the  Trustee on or before  the 30th day after the date of the Issuer  Notice (i)
irrevocable  written notice of the Holder's exercise of such right, which notice
shall set forth  the name of the  Holder,  the  amount of the  Securities  to be
redeemed (which shall be in any authorized  denomination),  and a statement that
an election to exercise the redemption right is being made thereby, and (ii) the
Securities with respect to which the redemption right is being  exercised,  duly
endorsed for transfer to the Issuer.  Securities held by a securities depositary
may be  delivered  in such other  manner as may be agreed to by such  securities
depositary and the Issuer. Such written notice shall be irrevocable.  Subject to
the provisions of subsection (d) below,  Securities  surrendered  for redemption
together with such irrevocable written notice shall cease to be convertible from
the date of delivery of such notice.  If the Change in Control  Repurchase  Date
falls after the record date and before the following  interest payment date, any
Securities to be redeemed must be  accompanied  by payment of an amount equal to
the interest  thereon which the registered  Holder thereof is to receive on such
interest  payment date,  and,  notwithstanding  such  redemption,  such interest
payment  will be made by the  Issuer to the  registered  Holder  thereof  on the
applicable record date.

                  (c) In the event a  redemption  right  shall be  exercised  in
accordance  with the terms hereof,  the Issuer shall pay or cause to be paid the
Change in  Control  Repurchase  Price in cash,  to the  Holder on the  Change in
Control  Repurchase Date. The Issue Price of and accrued Original Issue Discount
and accrued interest on Securities  payable at the Change in Control  Repurchase
Price on the  Change  in  Control  Repurchase  Date  shall be  considered  to be
principal  due on such date for purposes of this  Indenture,  including  Article
Four.

                  (d) If any Security surrendered for redemption shall not be so
redeemed  on the Change in  Control  Repurchase  Date,  such  Security  shall be
convertible  at any time  from the  Change  in  Control  Repurchase  Date  until
redeemed  and,  until  redeemed,  continue to bear  interest  (giving  effect to


                                      -89-
<PAGE>

accrual of Original  Issue  Discount) to the extent  permitted by applicable law
from the  Change  in  Control  Repurchase  Date at the same  rate  borne by such
Security.  The Issuer shall pay to the Holder of such  Security  the  additional
amount arising as a result of the provisions of this Section 13.2(d) at the same
time that it pays the Change in Control Repurchase Price, and if applicable such
Security shall remain  convertible into Class A Common Stock until the Change in
Control  Repurchase  Price plus any  additional  amounts  owing on such Security
shall have been paid or duly provided for.

                  (e) Any Security which is to be redeemed only in part shall be
surrendered  at any office or agency of the Issuer  designated  for that purpose
pursuant to Section 2.3 (with,  if the Issuer or the  Trustee so  requires,  due
endorsement by, or a written  instrument of transfer in form satisfactory to the
Issuer and the Trustee duly executed by, the Holder thereof or his attorney duly
authorized  in writing),  and the Issuer shall  execute,  and the Trustee  shall
authenticate  and deliver to the Holder of such Security without service charge,
a new Security or  Securities,  of any authorized  denomination  as requested by
such  Holder,  in  aggregate  principal  amount equal to and in exchange for the
unredeemed portion of the Security so surrendered.

                  SECTION  13.3  Definition  of Change in Control.  A "Change in
Control" is deemed to have  occurred when (i) any person or group other than one
or more of the Principal  Stockholders  (as  hereinafter  defined) or any person
employed by the Issuer in a management capacity as of September 28, 1999 (or any
group of which  any of them is a member,  collectively,  a  "Permitted  Owner"),
acquires  beneficial  ownership of,  directly or  indirectly,  shares of capital
stock of the Issuer  sufficient to entitle such person to exercise more than 50%
of the total  voting power of all classes of capital  stock  entitled to vote in
elections  of  directors  (whether by means of an exchange  offer,  liquidation,
tender   offer,   consolidation,    merger,    combination,    reclassification,
recapitalization or otherwise),  or (ii) the Issuer sells, leases,  exchanges or


                                      -90-
<PAGE>

transfers  (in one  transaction  or a series  of  related  transactions)  all or
substantially all of its assets to any person or group (in each instance, as the
term  "person"  or  "group"  is used in  Section  13(d)(3)  or  14(d)(2)  of the
Securities  Exchange Act of 1934, as amended),  other than one or more Permitted
Owners,  provided that any transaction  described in (i) or (ii) (whether or not
in any such case to or involving a Permitted  Owner) that results in the Class A
Common Stock (or a successor  common equity  security into which the  Securities
become  convertible  pursuant  to  Section  12.4) no  longer  being  listed on a
national  securities  exchange or traded on NASDAQ  shall also be  considered  a
Change in Control.  "Principal  Stockholders"  means Steven B. Dodge,  Thomas H.
Stoner,  Hicks, Muse, Tate & Furst  Incorporated,  Cox Telecom Towers,  Inc. and
Clear Channel Communications, Inc. and their Affiliates.

                  SECTION  13.4  Limitation  on  Right  to  Require  Redemption.
Notwithstanding  anything herein to the contrary, no Holder shall have any right
to require redemption pursuant to this Article if either (i) the Last Sale Price
(or if on any such  Trading  Day the Class A Common  Stock is not  quoted by any
organization referred to in the definition of Last Sale Price, the fair value of
the Class A Common Stock on such day, as conclusively determined by the Board of
Directors) on any five Trading Days during the 10 Trading Day period immediately
preceding  the date of the Change in Control  shall  equal or exceed 105% of the
Conversion  Price in effect on such  Trading  Days or (ii) with  respect  to any
transaction  described  in  clause  (i) of  Section  13.3,  or  any  transaction
described  in  clause  (ii) of  Section  13.3  (so long as such  transaction  is
accompanied  by  or  immediately   followed  by  the  complete  liquidation  and
dissolution  of the Issuer),  all the  consideration  to be paid for the Class A
Common  Stock  or the  assets,  as the  case  may  be,  in  the  transaction  or
transactions constituting the Change in Control (A) has an aggregate fair market
value of at least 105% of the  Conversion  Price with  respect to such  Holder's
Securities in effect  immediately  prior to the closing of such  transaction and
(B) consists of cash,  securities  traded on a national  securities  exchange or
quoted on NASDAQ or a combination of cash and securities.


                                      -91-
<PAGE>

                                ARTICLE FOURTEEN

                REPURCHASE OF SECURITIES AT OPTION OF THE HOLDER

                  SECTION  14.1  General.  Securities  shall be purchased by the
Issuer as of October 22, 2003 (the "Repurchase  Date"),  at the repurchase price
(the "Repurchase Price") set forth in the form of Security attached as Exhibit A
hereto, at the option of the Holder thereof, upon:

                  (1) delivery to the Paying  Agent,  by the Holder of a written
         notice  of  purchase  (the  "Repurchase  Notice")  at any time from the
         opening of business  on the date that is 20 Business  Days prior to the
         Repurchase  Date until the close of  business  on the  Repurchase  Date
         stating:

                           (A) the certificate  number of the Security which the
                  Holder will deliver to be purchased,

                           (B)  the  portion  of  the  principal  amount  of the
                  Security which the Holder will deliver to be purchased,  which
                  portion must be $1,000 or an integral multiple thereof,

                           (C) that such  Security  shall be purchased as of the
                  Repurchase Date pursuant to the terms and conditions specified
                  in the Securities and in this Indenture, and

                           (D) in the  event  the  Issuer  elects,  pursuant  to
                  Section  14.2,  to pay the  Repurchase  Price,  in whole or in
                  part,  in shares of Class A Common  Stock but such  portion of
                  the  Repurchase  Price  shall  ultimately  be  payable to such
                  Holder  entirely  in cash  because  any of the  conditions  to
                  payment of the Repurchase Price in Class A Common Stock is not
                  satisfied  prior to the close of  business  on the  Repurchase
                  Date, as set forth in Section 14.4, whether such Holder elects
                  (i) to withdraw  such  Repurchase  Notice as to some or all

                                      -92-
<PAGE>

                  of the  Securities  to which such  Repurchase  Notice  relates
                  (stating the principal  amount and certificate  numbers of the
                  Securities as to which such withdrawal shall relate),  or (ii)
                  to receive cash in respect of the entire  Repurchase Price for
                  all Securities (or portions  thereof) to which such Repurchase
                  Notice relates; and

                  (2) delivery of such Security to the Paying Agent prior to, on
         or after the Repurchase Date (together with all necessary endorsements)
         at the offices of the Paying Agent,  such delivery being a condition to
         receipt  by the  Holder of the  Repurchase  Price  therefor;  provided,
         however,  that the  Repurchase  Price shall be so paid pursuant to this
         Article only if the Security so delivered to the Trustee  shall conform
         in all respects to the  description  thereof in the related  Repurchase
         Notice.

                  If a Holder,  in such  Holder's  Repurchase  Notice and in any
written notice of withdrawal  delivered by such Holder  pursuant to the terms of
Section  14.9,  fails to  indicate  such  Holder's  choice  with  respect to the
election set forth in clause (D) of Section 14.1(1), such Holder shall be deemed
to have  elected to receive  cash in  respect  of the  Repurchase  Price for all
Securities  subject to such Repurchase  Notice in the circumstances set forth in
such clause (D).

                  The Issuer shall purchase from the Holder thereof, pursuant to
this Article, a portion of a Security if the principal amount of such portion is
$1,000 or an integral  multiple of $1,000.  Provisions  of this  Indenture  that
apply to the  purchase of all of a Security  also apply to the  purchase of such
portion of such Security.

                  Any  purchase  by  the  Issuer  contemplated  pursuant  to the
provisions  of  this  Article  shall  be  consummated  by  the  delivery  of the
consideration  to be received by the Holder promptly  following the later of the
Repurchase Date and the time of delivery of the Security.

                                      -93-
<PAGE>

                  Notwithstanding  anything  herein to the contrary,  any Holder
delivering to the Paying Agent a Repurchase Notice  contemplated by this Section
14.1 shall have the right to withdraw such  Repurchase  Notice at any time prior
to the close of business on the Repurchase  Date by delivery of a written notice
of withdrawal to the Paying Agent in accordance with Section 14.9.

                  The  Paying  Agent  shall  promptly  notify  the Issuer of the
receipt by it of any Repurchase Notice or written notice of withdrawal thereof.

                  SECTION  14.2  Issuer's  Right to Elect  Manner of  Payment of
Repurchase Price. The Securities to be purchased pursuant to Section 14.1 may be
paid for, at the election of the Issuer,  in cash or Class A Common Stock, or in
any combination of cash and Class A Common Stock,  subject to the conditions set
forth in  Sections  14.3 and 14.4.  The Issuer  shall  designate,  in the Issuer
Repurchase  Notice delivered  pursuant to Section 14.5,  whether the Issuer will
purchase the Securities  for cash or Class A Common Stock,  or, if a combination
thereof,  the  percentages of the  Repurchase  Price of Securities in respect of
which it will pay in cash or Class A Common Stock; provided that the Issuer will
pay cash for fractional interests in Class A Common Stock unless payment in cash
is  prohibited  by the  terms  of  the  Issuer's  indebtedness,  in  which  case
fractional  shares may be issued.  For purposes of determining  the existence of
potential fractional interests, all Securities subject to purchase by the Issuer
held by a Holder  shall be  considered  together  (no matter  how many  separate
certificates  are to be presented).  Each Holder whose  Securities are purchased
pursuant to this Article  shall  receive the same  percentage of cash or Class A
Common Stock in payment of the Repurchase Price for such Securities,  except (i)
as  provided  in  Section  14.4 with  regard to the  payment  of cash in lieu of
fractional  shares of Class A Common Stock and (ii) in the event that the Issuer
is unable to purchase the  Securities  of a Holder or Holders for Class A Common
Stock  because any  necessary  qualifications  or  registrations  of the Class A
Common Stock under  applicable  state  securities  laws cannot be obtained,  the
Issuer may  purchase  the  Securities  of such Holder or

                                      -94-
<PAGE>

Holders for cash.  The Issuer may not change its  election  with  respect to the
consideration  (or components or  percentages of components  thereof) to be paid
once the Issuer has given its Issuer Repurchase Notice to Securityholders except
pursuant to this  Section  14.2 or  pursuant  to Section  14.4 in the event of a
failure to satisfy,  prior to the close of business on the Repurchase  Date, any
condition to the payment of the Repurchase  Price, in whole or in part, in Class
A Common Stock.

                  At least  three  Business  Days  before the Issuer  Repurchase
Notice Date,  the Issuer shall deliver an Officers'  Certificate  to the Trustee
specifying:

                  (1) the manner of payment selected by the Issuer,

                  (2) the information required by Section 14.5,

                  (3) if the Issuer  elects to pay the  Repurchase  Price,  or a
         specified  percentage  thereof,  in  Class A  Common  Stock,  that  the
         conditions  to such  manner of payment  set forth in Section  14.4 have
         been or will be complied with, and

                  (4) whether the Issuer  desires the Trustee to give the Issuer
         Repurchase Notice required by Section 14.5.

                  SECTION 14.3 Repurchase with Cash. On the Repurchase  Date, at
the option of the Issuer, the Repurchase Price of Securities in respect of which
a  Repurchase  Notice  pursuant to Section  14.1 has been given,  or a specified
percentage  thereof,  may be paid by the Issuer with cash equal to the aggregate
Repurchase Price of such Securities. If the Issuer elects to purchase Securities
with cash, the Issuer  Repurchase  Notice, as provided in Section 14.5, shall be
sent to Holders (and the  Depositary  shall  distribute to beneficial  owners as
required  by  applicable  law)  not  less  than 20  Business  Days  prior to the
Repurchase Date (the "Issuer Repurchase Notice Date").

                  SECTION 14.4 Payment by Issuance of Class A Common  Stock.  On
the  Repurchase  Date,  at the option of the

                                      -95-
<PAGE>

Issuer,  the  Repurchase  Price of  Securities  in respect of which a Repurchase
Notice  pursuant  to Section  14.1 has been  given,  or a  specified  percentage
thereof,  may be paid by the  Issuer  by the  issuance  of a number of shares of
Class A Common Stock equal to the  quotient  obtained by dividing (i) the amount
of cash to which the  Securityholders  would have been  entitled  had the Issuer
elected  to pay all or such  specified  percentage,  as the case may be,  of the
Repurchase  Price of such Securities in cash by (ii) the Market Price of a share
of Class A Common Stock, subject to the next succeeding paragraph.

                  The Issuer will not issue a fractional share of Class A Common
Stock in payment of the Repurchase  Price.  Instead the Issuer will pay cash for
the current market value of the fractional  share. The current market value of a
fraction of a share shall be determined by multiplying  the Market Price by such
fraction and rounding the product to the nearest  whole cent.  It is  understood
that if a Holder elects to have more than one Security purchased,  the number of
shares  of Class A Common  Stock  shall be  based  on the  aggregate  amount  of
Securities to be purchased.

                  If  the  Issuer  elects  to  purchase  the  Securities  by the
issuance of shares of Class A Common Stock,  the Issuer  Repurchase  Notice,  as
provided in Section 14.5, shall be sent to the Holders (and the Depositary shall
distribute  to beneficial  owners as required by applicable  law) not later than
the Issuer Repurchase Notice Date.

                  The  Issuer's  right to exercise  its election to purchase the
Securities  pursuant to this  Article  through the issuance of shares of Class A
Common Stock shall be conditioned upon:

                  (1) the Issuer's not having given its Issuer Repurchase Notice
         of an election to pay  entirely in cash and its giving a timely  Issuer
         Repurchase Notice of election to purchase all or a specified percentage
         of the Securities with Class A Common Stock as provided herein;

                                      -96-
<PAGE>

                  (2) the  registration of the shares of Class A Common Stock to
         be issued in respect of the payment of the  Repurchase  Price under the
         Securities Act or the Exchange Act, in each case, if required;

                  (3)  any  necessary   qualification   or  registration   under
         applicable  state  securities laws or the  availability of an exemption
         from such qualification and registration; and

                  (4) the receipt by the Trustee of an Officers' Certificate and
         an Opinion of Counsel  each  stating that (A) the terms of the issuance
         of the Class A Common Stock are in conformity  with this  Indenture and
         (B) the  shares of Class A Common  Stock to be issued by the  Issuer in
         payment of the Repurchase Price in respect of Securities have been duly
         authorized and, when issued and delivered pursuant to the terms of this
         Indenture  in  payment  of  the  Repurchase  Price  in  respect  of the
         Securities,  will be validly issued, fully paid and non-assessable and,
         to the best of such counsel's  knowledge,  free from preemptive rights,
         and, in the case of such Officers' Certificate, stating that conditions
         (1), (2) and (3) above and the information  publication requirement set
         forth in the second sentence of the next succeeding paragraph have been
         satisfied  and, in the case of such  Opinion of Counsel,  stating  that
         conditions (2) and (3) above have been satisfied.

                  Such Officers'  Certificate shall also set forth the number of
         shares of Class A Common  Stock to be issued for each $1,000  principal
         amount  of  Securities  and the Last  Sale  Price of a share of Class A
         Common  Stock on each Trading Day during the period  commencing  on the
         first  Trading  Day of the  period  during  which the  Market  Price is
         calculated  and ending on the  Repurchase  Date. The Issuer may pay the
         Repurchase  Price (or any portion thereof) in Class A Common Stock only
         if the information necessary to calculate the Market Price is published
         in  a  daily  newspaper  of  national  circulation.  If  the  foregoing
         conditions  are not satisfied with

                                      -97-
<PAGE>

         respect to a Holder or Holders  prior to the close of  business  on the
         Repurchase  Date and the Issuer has elected to purchase the  Securities
         pursuant  to this  Article  through  the  issuance of shares of Class A
         Common Stock,  the Issuer shall pay the entire  Repurchase Price of the
         Securities of such Holder or Holders in cash.

                  The "Market  Price"  means the average of the Last Sale Prices
of the Class A Common  Stock for the five  Trading Day period  ending on (if the
third  Business  Day prior to the  Repurchase  Date is a Trading Day, or if not,
then on the last  Trading  Day  prior to) the  third  Business  Day prior to the
Repurchase  Date,  appropriately  adjusted to take into account the  occurrence,
during the period  commencing on the first of such Trading Days during such five
Trading Day period and ending on the Repurchase  Date, of any event described in
Sections 12.4(a),  12.4(b) or 12.4(c),  subject,  however, to the conditions set
forth in Section 12.4(f).

                  SECTION  14.5  Notice  of  Election.  The  Issuer's  notice of
election  to  purchase  with  cash or  Class A Common  Stock or any  combination
thereof  shall be sent to the Holders (and to  beneficial  owners as required by
applicable  law) in the manner provided in Section 10.4 at the time specified in
Section 14.3 or 14.4,  as  applicable  (the "Issuer  Repurchase  Notice").  Such
Issuer  Repurchase  Notice  shall state the manner of payment  elected and shall
contain the following information:

                  In the event the  Issuer  has  elected  to pay the  Repurchase
         Price (or a specified  percentage  thereof)  with Class A Common Stock,
         the Issuer Repurchase Notice
         shall:

                           (1)  state  that each  Holder  will  receive  Class A
                  Common Stock with a Market Price  determined as of a specified
                  date  prior to the  Repurchase  Date  equal to such  specified
                  percentage of the Repurchase  Price of the Securities  held by
                  such

                                      -98-
<PAGE>

                  Holder  (except  any  cash  amount  to  be  paid  in  lieu  of
                  fractional shares);

                           (2) set forth the  method of  calculating  the Market
                  Price of the Class A Common Stock as required by Section 14.4;
                  and

                           (3) state that,  because the Market  Price of Class A
                  Common Stock will be determined  prior to the Repurchase Date,
                  Holders will bear the market risk with respect to the value of
                  the  Class A Common  Stock to be  received  from the date such
                  Market Price is determined to the Repurchase Date.

                  In any case,  each Issuer  Repurchase  Notice shall  include a
         form of Repurchase Notice to be completed by a Securityholder and shall
         state:

                           (A) the Repurchase Price and the Conversion Price;

                           (B) the name and address of the Paying  Agent and the
                  Conversion Agent;

                           (C) that  Securities as to which a Repurchase  Notice
                  has been given may be  converted  pursuant  to Article  Twelve
                  only if the applicable Repurchase Notice has been withdrawn in
                  accordance with the terms of this Indenture;

                           (D) that Securities must be surrendered to the Paying
                  Agent to collect payment;

                           (E) that the Repurchase  Price for any security as to
                  which a  Repurchase  Notice has been  given and not  withdrawn
                  will be paid promptly  following  the later of the  Repurchase
                  Date and the time of surrender  of such  Security as described
                  in (D) above;

                                      -99-
<PAGE>

                           (F) the procedures the Holder must follow to exercise
                  rights  under this  Article and a brief  description  of those
                  rights;

                           (G) briefly, the conversion rights of the Securities;
                  and

                           (H)  the  procedures  for  withdrawing  a  Repurchase
                  Notice  (including,  without  limitation,  for  a  conditional
                  withdrawal  pursuant  to the terms of  Section  14.1(1)(D)  or
                  Section 14.9).

                  At the Issuer's  request,  the Trustee  shall give such Issuer
Repurchase  Notice in the Issuer's name and at the Issuer's  expense;  provided,
however,  that, in all cases, the text of such Issuer Repurchase Notice shall be
prepared by the Issuer.

                  Upon  determination  of the actual number of shares of Class A
Common Stock to be issued for each $1,000  principal  amount of Securities,  the
Issuer will publish such determination in a newspaper of national circulation.

                  SECTION 14.6  Covenants  of the Issuer.  All shares of Class A
Common Stock  delivered  upon purchase of the  Securities  shall be newly issued
shares or treasury shares, shall be duly authorized,  validly issued, fully paid
and  non-assessable  by the Issuer and shall be free of preemptive rights of any
lien or adverse claim.

                  If the Class A Common  Stock is then  listed  on any  national
securities  exchange or quoted on NASDAQ,  the shares of Class A Common Stock to
be issued to purchase  Securities will be similarly listed or quoted at the time
of such issuance.

                  SECTION  14.7  Procedure  upon  Repurchase.  The Issuer  shall
deposit cash (in respect of a cash purchase under Section 14.3 or for fractional
interests,  as applicable)  or shares of Class A Common Stock,  or a combination
thereof,  as  applicable,  at the time and in the manner as  provided in Section
14.10,  sufficient to pay the


                                     -100-
<PAGE>

aggregate  Repurchase  Price of all Securities to be purchased on the Repurchase
Date pursuant to this Article. As soon as practicable after the Repurchase Date,
the Issuer shall deliver to each Holder entitled to receive Class A Common Stock
through the Paying Agent a certificate  for the number of full shares of Class A
Common Stock issuable in payment of the Repurchase Price and cash in lieu of any
fractional  interests.  The  Person in whose  name the  certificate  for Class A
Common Stock is  registered  shall be treated as a holder of record of shares of
Class A Common Stock on the Business Day following the Repurchase Date.  Subject
to Section  14.4,  no payment or  adjustment  will be made for  dividends on the
Class A Common  Stock  the  record  date for which  occurred  on or prior to the
Repurchase Date.

                  SECTION 14.8 Taxes. If a Holder of a Security is paid in Class
A Common Stock, the Issuer shall pay any documentary,  stamp or similar issue or
transfer  taxes  payable  to the  United  Sates  of  America  or  any  political
subdivision or taxing  authority  thereof in respect of the issuance or delivery
of such Class A Common Stock;  provided,  however,  that the Issuer shall not be
required to pay any tax which may be payable in respect of any transfer involved
in the issuance of shares of Class A Common Stock, and no such issue or delivery
shall be made unless and until the Person  requesting such issue or delivery has
paid to the  Issuer  or the  Paying  Agent  the  amount  of any  such tax or has
established,  to the  satisfaction of the Issuer or the Paying Agent,  that such
tax has been paid.  Nothing  herein shall  preclude  any income tax  withholding
required by law or regulations.

                  SECTION 14.9 Effect of Repurchase Notice.  Upon receipt by the
Paying Agent of the Repurchase  Notice, the Holder of the Security in respect of
which such Repurchase  Notice was given shall (unless such Repurchase  Notice is
withdrawn as specified in the following two  paragraphs)  thereafter be entitled
to  receive  solely the  Repurchase  Price with  respect to such  Security.  The
Repurchase  Price  shall be paid to such  Holder,  subject  to  receipt of funds
and/or securities by the Paying Agent,  promptly  following the later of (x) the
Repurchase Date with respect to such

                                     -101-
<PAGE>

Security  (provided the conditions in Section 14.1 have been  satisfied) and (y)
the time of delivery of such Security to the Paying Agent by the Holder  thereof
in the  manner  required  by  Section  14.1.  Securities  in  respect of which a
Repurchase  Notice  has been given by the Holder  thereof  may not be  converted
pursuant  to  Article  Twelve  on or  after  the  date of the  delivery  of such
Repurchase Notice unless such Repurchase Notice has first been validly withdrawn
as specified in the  following  two  paragraphs.  The Issue Price of and accrued
Original  Discount  on  Securities  payable  as  the  Repurchase  Price  on  the
Repurchase  Date  shall  be  considered  to be  principal  due on such  date for
purposes of this Indenture, including Article Four.

                  A  Repurchase  Notice may be  withdrawn  by means of a written
notice of  withdrawal  delivered to the office of the Paying Agent in accordance
with the  Repurchase  Notice at any time prior to the close of  business  on the
Repurchase Date specifying:

                  (1) the certificate number of the Security in respect of which
         such notice of withdrawal is being submitted;

                  (2) the principal amount of the Security with respect to which
         such notice of withdrawal is being submitted; and

                  (3) the  principal  amount,  if any,  of such  Security  which
         remains subject to the original Repurchase Notice and which has been or
         will be delivered for purchase by the Issuer.

                  A written  notice of withdrawal of a Repurchase  Notice may be
in the form set forth in the preceding  paragraph or may be in the form of (i) a
conditional withdrawal contained in a Repurchase Notice pursuant to the terms of
Section 14.1(1)(D) or (ii) a conditional  withdrawal  containing the information
set forth in Section  14.1(1)(D) and the preceding  paragraph and contained in a
written  notice of withdrawal  delivered to the Paying Agent as set forth in the
preceding paragraph.

                                     -102-
<PAGE>

                  There shall be no purchase of any Securities  pursuant to this
Article  (other than  through the issuance of Class A Common Stock in payment of
the Repurchase Price,  including cash in lieu of fractional shares) if there has
occurred (prior to, on or after, as the case may be, the giving,  by the Holders
of such  Securities,  of the required  Repurchase  Notice) and is  continuing an
Event of Default  (other than a default in the payment of the  Repurchase  Price
with respect to such  Securities).  The Paying Agent will promptly return to the
respective Holders thereof any Securities (x) with respect to which a Repurchase
Notice has been withdrawn in compliance with this  Indenture,  or (y) held by it
during  the  continuance  of an Event of  Default  (other  than a default in the
payment of the Repurchase  Price with respect to such Securities) in which case,
upon such return,  the Repurchase Notice with respect thereto shall be deemed to
have been withdrawn.

                  SECTION 14.10 Deposit of Repurchase Price. Prior to 11:00 a.m.
(New York City time) on the  Repurchase  Date the Issuer shall  deposit with the
Trustee or with one or more  Paying  Agents  (or, if the Issuer is acting as its
own Paying Agent,  shall segregate and hold in trust as provided in Section 2.3)
an amount of money (in immediately available funds if deposited on such Business
Day) or Class A Common  Stock,  if permitted  hereunder,  sufficient  to pay the
aggregate Repurchase Price of all of the Securities or portions thereof that are
to be purchased as of the Repurchase Date.

                  SECTION 14.11  Securities  Repurchased  in Part.  Any Security
which is to be purchased  only in part shall be surrendered at the office of the
Paying Agent (with,  if the Issuer or the Trustee so requires,  due  endorsement
by, or a written  instrument of transfer in form  satisfactory  to the Issuer or
the Trustee duly executed by, the Holder thereof or such Holder's  attorney duly
authorized  in writing)  and the Issuer  shall  execute  and the  Trustee  shall
authenticate and deliver to the Holder of such Security, without service charge,
a new Security or  Securities,  of any authorized  denomination  as requested by
such Holder in aggregate  principal  amount  equal to, and in exchange  for, the
portion

                                     -103-
<PAGE>

of the principal amount of the Security so surrendered which is not purchased.

                  SECTION  14.12  Issuer to  Comply  with  Securities  Laws Upon
Purchase of Securities.  In connection with any offer to purchase or purchase of
Securities under this Article (provided that such offer or purchase  constitutes
an "issuer tender offer" for purposes of Rule 13e-4 (which term, as used herein,
includes any successor  provision thereto) under the Exchange Act at the time of
such offer or  purchase),  the Issuer  shall (i) comply with Rule 13e-4 and Rule
14e-1  under the  Exchange  Act,  (ii) file the related  Schedule  13E-4 (or any
successor schedule,  form or report) under the Exchange Act, and (iii) otherwise
comply with all Federal and state securities laws so as to permit the rights and
obligations  under this  Article to be  exercised  in the time and in the manner
specified in this Article.

                  SECTION  14.13  Repayment  to the Issuer.  The Trustee and any
Paying  Agent  shall  return to the  Issuer any cash or shares of Class A Common
Stock that remain  unclaimed as provided in Section 9.4,  together with interest
or  dividends,  if any,  thereon held by them for the payment of the  Repurchase
Price  upon  Issuer  Order;  provided,  however,  that to the  extent  that  the
aggregate  amount  of cash or shares of Class A Common  Stock  deposited  by the
Issuer pursuant to Section 14.10 exceeds the aggregate  Repurchase  Price of the
Securities  or portions  thereof which the Issuer is obligated to purchase as of
the  Repurchase  Date,  then  promptly  after the  Business  Day  following  the
Repurchase  Date the Trustee shall return any such excess to the Issuer together
with interest or dividends, if any, thereon.


                                     -104-
<PAGE>


                  IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Indenture to be duly executed, all as of October 4, 1999.



                                     AMERICAN TOWER CORPORATION



                                     By  /s/ Joseph L. Winn
                                       Name: Joseph L. Winn
                                       Title: Chief Financial Officer
Attest:



By /s/ Adam Benjamin
Name:  Adam Benjamin
Title: Assistant Secretary
                                     THE BANK OF NEW YORK, not in
                                              its individual capacity but
                                              solely as Trustee



                                     By /s/ Van Brown
                                     Name:  Van Brown
                                     Title: Assistant Vice President





                                     -105-
<PAGE>

                                                                       EXHIBIT A


                           [FORM OF FACE OF SECURITY]

THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH SECURITY:

THIS SECURITY IS ISSUED WITH ORIGINAL ISSUE DISCOUNT. THE ISSUE PRICE IS $705.20
PER $1,000 PRINCIPAL AMOUNT AT MATURITY.  THE ISSUE DATE IS OCTOBER 4, 1999. THE
YIELD TO MATURITY IS 6.25% PER ANNUM.

THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH RESTRICTED  SECURITY OTHER
THAN ANY RESTRICTED GLOBAL SECURITY:

                  THIS  SECURITY  (OR ITS  PREDECESSOR)  AND ANY  CLASS A COMMON
STOCK  ISSUED ON  CONVERSION  HEREOF HAVE NOT BEEN  REGISTERED  UNDER THE UNITED
STATES  SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES  ACT"), OR ANY STATE
SECURITIES LAW AND MAY NOT BE OFFERED,  SOLD,  PLEDGED OR OTHERWISE  TRANSFERRED
EXCEPT  (A)(1) TO A PERSON WHO THE SELLER  REASONABLY  BELIEVES  IS A  QUALIFIED
INSTITUTIONAL  BUYER  WITHIN THE MEANING OF RULE 144A UNDER THE  SECURITIES  ACT
PURCHASING  FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED  INSTITUTIONAL
BUYER IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (2) PURSUANT TO AN
EXEMPTION  FROM  REGISTRATION  UNDER THE  SECURITIES  ACT  PROVIDED  BY RULE 144
THEREUNDER  (IF  AVAILABLE),  OR  (3)  PURSUANT  TO  AN  EFFECTIVE  REGISTRATION
STATEMENT  UNDER THE SECURITIES  ACT, AND (B) IN ACCORDANCE  WITH ALL APPLICABLE
SECURITIES LAWS OF THE STATES OF THE UNITED STATES.

                  EACH  PURCHASER OF THIS  SECURITY IS HEREBY  NOTIFIED THAT THE
SELLER OF THIS SECURITY MAY BE RELYING ON THE EXEMPTION  FROM THE  PROVISIONS OF
SECTION 5 OF THE SECURITIES ACT PROVIDED BY RULE 144A THEREUNDER.
<PAGE>

THE  FOLLOWING  LEGEND  SHALL  APPEAR  ON THE  FACE  OF EACH  RESTRICTED  GLOBAL
SECURITY:

                  THE  SECURITIES  EVIDENCED  BY THIS GLOBAL  SECURITY (OR THEIR
PREDECESSORS)  AND ANY  CLASS A  COMMON  STOCK  ISSUED  ON  CONVERSION  OF THOSE
SECURITIES  HAVE NOT BEEN REGISTERED  UNDER THE UNITED STATES  SECURITIES ACT OF
1933, AS AMENDED (THE "SECURITIES ACT"), OR ANY STATE SECURITIES LAW AND MAY NOT
BE  OFFERED,   SOLD,  PLEDGED  OR  OTHERWISE   TRANSFERRED  IN  THE  ABSENCE  OF
REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM.

                  EACH BENEFICIAL  OWNER OF AN INTEREST IN ANY OF THE SECURITIES
EVIDENCED BY THIS GLOBAL  SECURITY  (INCLUDING ANY PARTICIPANT IN THE DEPOSITARY
HOLDING  THE GLOBAL  SECURITY  THAT IS SHOWN AS HOLDING  SUCH AN INTEREST ON THE
RECORDS OF SUCH DEPOSITARY AND EACH BENEFICIAL OWNER THAT HOLDS THROUGH ANY SUCH
PARTICIPANT) AGREES FOR THE BENEFIT OF AMERICAN TOWER CORPORATION (THE "ISSUER")
THAT (I) ANY  BENEFICIAL  INTEREST IN THE  SECURITIES  AND ANY SHARES OF CLASS A
COMMON STOCK ISSUABLE UPON THEIR CONVERSION MAY BE RESOLD,  PLEDGED OR OTHERWISE
TRANSFERRED  ONLY  (A)(1) TO A PERSON WHO THE SELLER  REASONABLY  BELIEVES  IS A
QUALIFIED  INSTITUTIONAL  BUYER  WITHIN  THE  MEANING  OF RULE  144A  UNDER  THE
SECURITIES  ACT PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED
INSTITUTIONAL  BUYER IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (2)
PURSUANT TO AN EXEMPTION FROM REGISTRATION  UNDER THE SECURITIES ACT PROVIDED BY
RULE 144 THEREUNDER (IF AVAILABLE), OR (3) PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT  UNDER THE SECURITIES  ACT, AND (B) IN ACCORDANCE  WITH ALL APPLICABLE
SECURITIES LAWS OF THE STATES OF THE UNITED STATES AND (II) THE BENEFICIAL OWNER
WILL,  AND  EACH  SUBSEQUENT  BENEFICIAL  OWNER  OF AN  INTEREST  IN  ANY OF THE
SECURITIES  EVIDENCED  BY THIS  GLOBAL  SECURITY  OR ANY  CLASS A  COMMON  STOCK
ISSUABLE  UPON  CONVERSION  THEREOF IS REQUIRED TO,  NOTIFY ANY PURCHASER OF ANY
BENEFICIAL INTEREST IN THE SECURITIES OR SUCH CLASS A COMMON STOCK ISSUABLE UPON
ITS CONVERSION FROM IT OF THE RESALE RESTRICTIONS REFERRED TO IN (I) ABOVE.

                  EACH PURCHASER OF ANY BENEFICIAL INTEREST IN THE SECURITIES IS
HEREBY  NOTIFIED THAT THE SELLER OF SUCH

                                      -2-
<PAGE>

BENEFICIAL  INTEREST  MAY BE RELYING ON THE  EXEMPTION  FROM THE  PROVISIONS  OF
SECTION 5 OF THE SECURITIES ACT PROVIDED BY RULE 144A THEREUNDER.

THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL SECURITY:

                  THIS SECURITY IS A GLOBAL  SECURITY  WITHIN THE MEANING OF THE
INDENTURE  HEREINAFTER  REFERRED  TO  AND  IS  REGISTERED  IN  THE  NAME  OF THE
DEPOSITARY OR A NOMINEE OF THE  DEPOSITARY,  WHICH MAY BE TREATED BY THE ISSUER,
THE TRUSTEE AND ANY AGENT  THEREOF AS OWNER AND HOLDER OF THIS  SECURITY FOR ALL
PURPOSES.  THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL SECURITY
FOR WHICH THE DEPOSITORY TRUST COMPANY IS TO BE THE DEPOSITARY:

                  UNLESS  THIS   CERTIFICATE   IS  PRESENTED  BY  AN  AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION  ("DTC"),
TO THE ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER,  EXCHANGE,  OR PAYMENT,
AND ANY  CERTIFICATE  ISSUED IS  REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH
OTHER  NAME AS IS  REQUESTED  BY AN  AUTHORIZED  REPRESENTATIVE  OF DTC (AND ANY
PAYMENT  IS MADE TO CEDE & CO. OR TO SUCH  OTHER  ENTITY AS IS  REQUESTED  BY AN
AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR
VALUE OR  OTHERWISE BY OR TO ANY PERSON IS WRONGFUL  INASMUCH AS THE  REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.




                                      -3-
<PAGE>





No.                                                                $
                                                                   [CUSIP NO.]

                           American Tower Corporation

                        2.25% Convertible Notes Due 2009


                  American Tower Corporation (the "Issuer"),  for value received
hereby  promises to pay to _________ or registered  assigns the principal sum of
_________  Dollars (which principal amount may from time to time be increased or
decreased  to such other  principal  amounts  (which,  taken  together  with the
principal  amounts  of  all  other  Outstanding  Securities,  shall  not  exceed
$468,050,000 in the aggregate at any time) by adjustments made on the records of
the Trustee  hereinafter  referred to in accordance  with the  Indenture) at the
Issuer's office or agency for said purpose in the Borough of Manhattan, The City
of New York,  on October 15, 2009, in such coin or currency of the United States
of America as at the time of payment  shall be legal  tender for the  payment of
public and private  debts,  and to pay interest,  semi-annually  on April 15 and
October 15 of each year and at maturity,  on said  principal sum in like coin or
currency at the rate per annum set forth above  beginning on April 15, 2000,  or
from the most recent date to which  interest has been paid or duly  provided for
on the  Securities.  The interest so payable on any April 15 or October 15 will,
except as otherwise provided in the Indenture referred to on the reverse hereof,
be paid to the person in whose name this  Security is registered at the close of
business on the March 31 or September 30 preceding  such April 15 or October 15,
whether or not such day is a business  day;  provided that interest may be paid,
at the  option  of the  Issuer,  by  mailing  a check  therefor  payable  to the
registered  Holder  entitled  thereto  at his last  address as it appears on the
Security register.

                  Reference is made to the further  provisions  set forth on the
reverse hereof, including without limitation


                                      -4-
<PAGE>


provisions  giving the Holder  hereof the right to convert  this  Security  into
Class A Common  Stock of the Issuer on the terms and  subject to the  conditions
and limitations  referred to on the reverse  hereof,  as more fully specified in
the  Indenture.  Such further  provisions  shall for all purposes  have the same
effect as though fully set forth at this place.

                  This  Security  shall  not be valid or  obligatory  until  the
certificate of authentication  hereon shall have been duly signed by the Trustee
acting under the Indenture.

                  IN WITNESS  WHEREOF,  the Issuer has caused this instrument to
be duly executed under its corporate seal.


Dated:

[Seal]

                                            AMERICAN TOWER CORPORATION



                                            By____________________________



                                            By____________________________




                                      -5-
<PAGE>



                          [FORM OF REVERSE OF SECURITY]

                           American Tower Corporation

                        2.25% Convertible Notes Due 2009



                  This  Security  is one  of a duly  authorized  issue  of  debt
securities  of the Issuer,  limited to up to the aggregate  principal  amount of
$425,500,000,  or up to $468,050,000 if an option is fully exercised  (except as
otherwise  provided  in the  Indenture  defined  below),  issued or to be issued
pursuant to an  indenture  dated as of October 4, 1999 (the  "Indenture"),  duly
executed and  delivered  by the Issuer to The Bank of New York,  as Trustee (the
"Trustee").  Reference  is  hereby  made to the  Indenture  and  all  indentures
supplemental  thereto for a description  of the rights,  limitations  of rights,
obligations, duties and immunities thereunder of the Trustee, the Issuer and the
Holders  (the word  "Holders"  or  "Holder"  meaning the  registered  Holders or
registered  Holder)  of the  Securities.  Terms used but not  otherwise  defined
herein shall have the meanings assigned thereto in the Indenture.

                  In case an Event of  Default,  as  defined  in the  Indenture,
shall have occurred and be  continuing,  the sum of the Issue Price plus accrued
Original Issue Discount of all the Securities and interest  accrued  thereon may
be declared due and payable,  in the manner and with the effect,  and subject to
the  conditions,  provided in the  Indenture.  The  Indenture  provides  that in
certain  events a declaration  of default,  a default,  or the  consequences  of
either of them may be waived by the Holders of a majority in aggregate principal
amount of the  Securities  then  outstanding  except a default in the payment of
principal, Change in Control Repurchase Price or Repurchase Price of or premium,
if any, or interest or accrued  Original Issue Discount on any of the Securities
or in respect of the  conversion of any of the  Securities.  Any such consent or
waiver  by the  Holder of this  Security  (unless  revoked  as  provided  in the
Indenture)  shall be conclusive and binding upon such Holder and upon



                                      -6-
<PAGE>

all future  Holders and owners of this  Security and any  Security  which may be
issued in exchange or substitution  hereof,  whether or not any notation thereof
is made upon this Security or such other Securities.

                  The Indenture permits the Issuer and the Trustee,  without the
consent of any of the Holders under the  circumstances  described in Section 7.1
of the  Indenture,  and with  the  consent  of the  Holders  of not less  than a
majority  in  aggregate   principal   amount  of  the  Securities  at  the  time
outstanding,  evidenced as in the Indenture  provided,  to execute  supplemental
indentures adding any provisions to or changing in any manner or eliminating any
of the provisions of the Indenture or of any supplemental indenture or modifying
in any manner the rights of the Holders of the Securities; provided that no such
supplemental  indenture shall (a) extend the final maturity of any Security,  or
reduce the principal amount thereof or premium,  if any, thereon,  or reduce the
rate or extend the time of payment of interest  thereon,  or any premium payable
on the redemption  thereof,  or change the rate of accrual or extend the time of
payment in connection with Original Issue Discount thereon,  or change the place
of payment where,  or the coin or currency in which,  any principal,  premium or
interest is payable,  or reduce or alter the method of computation of any amount
payable on  redemption,  repurchase  or repayment  thereof (or the time at which
such  redemption,  repurchase or repayment may be made),  or impair or adversely
affect the right of any  Securityholder  to  institute  suit for the  payment or
conversion  thereof or adversely affect the right to convert the Securities into
Class A Common  Stock of the  Issuer,  in each case,  without the consent of the
Holder of the  Security  so  affected;  provided no consent of any Holder of any
Security  will be  necessary  to permit  the  Trustee  and the Issuer to execute
supplemental  indentures under the circumstances  provided in Section 7.1(e) and
Section  12.5 of the  Indenture,  or (b)  reduce  the  aforesaid  percentage  in
principal amount of Securities,  the consent of the Holders of which is required
for any such supplemental indenture,  without the consent of the Holders of each
Security so affected,  or (c) reduce the  percentage of Securities  necessary to
consent to waive any past default  under the


                                      -7-
<PAGE>

Indenture  to less than a  majority,  without the consent of the Holders of each
Security  so  affected;  or (d) modify any of the  provisions  of the  Indenture
relating  to  supplemental  indentures  or waivers of past  defaults,  except to
increase  any  percentage  provided  for in Section  4.10 or Section  7.2 of the
Indenture or to provide that certain other provisions of the Indenture cannot be
modified or waived  without the consent of the Holder of each Security  affected
thereby.

                  Subject to the provisions of the Indenture, the Holder of this
Security has the right, at his option, at any time until and including,  but not
after the close of business  on,  October 15, 2009  (except  that,  in case this
Security or a portion hereof shall be called for redemption and the Issuer shall
not thereafter default in making due provision for the payment of the redemption
price,  such right shall terminate with respect to this Security or such portion
hereof at the close of business on the  Business Day prior to the date fixed for
redemption),  to convert the principal  amount of this Security,  or any portion
thereof which is $1,000 or an integral  multiple of $1,000,  into fully paid and
non-assessable  shares of Class A Common  Stock of the  Issuer,  as said  shares
shall be  constituted  at the date of  conversion,  at the  conversion  price of
$24.00 in Issue Price of Securities for each share of such Class A Common Stock,
or at the adjusted  conversion  price in effect at the date of  conversion if an
adjustment  has  been  made,  determined  as  provided  in the  Indenture,  upon
surrender  of this  Security to the Issuer at the office or agency of the Issuer
maintained  for that purpose in the Borough of Manhattan,  The City of New York,
together with a fully executed notice substantially in the form set forth at the
foot hereof that the Holder  elects so to convert this  Security (or any portion
hereof which is an integral  multiple of $1,000  principal  amount) and, if this
Security is surrendered  for  conversion  during the period between the close of
business on March 31 or  September 30 in any year and the opening of business on
the following April 15 or October 15 and has not been called for redemption on a
redemption  date  within  such  period (or on such April 15 or October  15),  or
within five days after such period, accompanied by payment of an amount equal to
the interest


                                      -8-
<PAGE>

payable on such April 15 or October 15 on the  principal  amount of the Security
being surrendered for conversion.  Except as provided in the preceding  sentence
or as otherwise  expressly  provided in the Indenture,  no payment or adjustment
shall be made on account of interest or Original Issue Discount  accrued on this
Security  (or portion  thereof) so  converted  or on account of any  dividend or
distribution on any such Common Stock issued upon conversion,  but the Holder of
record of this Security on March 31 or September 30 shall be entitled to receive
interest  on  such   Security  on  the   succeeding   April  15  or  October  15
notwithstanding  the  conversion  of such  Security  prior  to such  April 15 or
October 15. If so required by the Issuer or the  Trustee,  this  Security,  upon
surrender  for  conversion  as  aforesaid,  shall  be duly  endorsed  by,  or be
accompanied by instruments of transfer, in form satisfactory to the Issuer, duly
executed by, the Holder or by his duly authorized attorney. The conversion price
from  time to time in  effect  is  subject  to  adjustment  as  provided  in the
Indenture.  No  fractions  of shares will be issued on  conversion.  In the sole
discretion of the Board of Directors,  any fractional interest may be rounded up
to the  nearest  full  share,  or an  adjustment  in cash  will be made  for any
fractional  interest,  in either case in accordance  with and as provided in the
Indenture.

                  No reference  herein to the Indenture and no provision of this
Security or of the Indenture shall alter or impair the obligation of the Issuer,
which is absolute and  unconditional,  to pay the  principal of and premium,  if
any, and interest on this  Security at the place,  times,  and rate,  and in the
currency, herein prescribed.

                  The  Securities  are issuable  only as  registered  Securities
without coupons in  denominations  of $1,000  principal  amount and any integral
multiple of $1,000.

                  In the manner and subject to the  limitations  provided in the
Indenture,  this Security may be exchanged for a like aggregate principal amount
of Securities of other authorized denominations.

                                      -9-
<PAGE>

                  Upon due  presentment  for  registration  of  transfer of this
Security at the  above-mentioned  office or agency of the Issuer, a new Security
or  Securities  of  authorized  denominations,  for a like  aggregate  principal
amount,  will be issued to the  transferee  as  provided  in the  Indenture.  No
service charge shall be made for any such  transfer,  but the Issuer may require
payment of a sum sufficient to cover any tax or other  governmental  charge that
may be imposed in relation thereto.

                  The  Securities may be redeemed at the option of the Issuer as
a whole,  or from time to time in part,  on and after  October  22,  2003,  upon
mailing a notice of such redemption not less than 20 nor more than 60 days prior
to the date fixed for  redemption  to the Holders of  Securities to be redeemed,
all as provided in the Indenture,  at the following redemption prices per $1,000
principal   amount  (which  prices  reflect  accrued   Original  Issue  Discount
calculated  to each such date),  together in each case with accrued  interest to
the date fixed for  redemption.  The  redemption  price of a  Security  redeemed
between such dates would include an additional  amount reflecting the additional
Original  Issue  Discount  accrued since the next preceding date in the table to
the actual date fixed for redemption.


                         (1)                   (2)                  (3)
                                             Accrued
                    Security Issue        Original Issue      Redemption Price
Redemption Date         Price                Discount            (1)  +  (2)
- --------------------------------------------------------------------------------


October 22, 2003       $705.20              $ 97.73              $  802.93
October 15, 2004       $705.20              $125.28              $  830.48
October 15, 2005       $705.20              $155.14              $  860.34
October 15, 2006       $705.20              $186.90              $  892.10
October 15, 2007       $705.20              $220.68              $  925.88
October 15, 2008       $705.20              $256.60              $  961.80
October 15, 2009       $705.20              $294.80              $1,000.00


                  The  Securities  do not have the benefit of any  sinking  fund
obligations.

                  If at any time  there  shall  occur any  Change in  Control as
defined in the Indenture  with respect to the

                                      -10-
<PAGE>

Issuer,  each Holder of Securities  shall,  except as otherwise  provided in the
Indenture, have the right, at such Holder's option but subject to the conditions
set forth in the  Indenture,  to  require  the Issuer to redeem on the Change in
Control  Repurchase  Date as  defined in the  Indenture  all or any part of such
Holder's  Securities  that is $1,000  principal  amount or an integral  multiple
thereof at a Change in Control  Repurchase  Price  equal to the sum of the Issue
Price thereof plus accrued  Original Issue Discount to the Repurchase  Date, and
accrued and unpaid  interest,  if any, up to but excluding the Change in Control
Repurchase Date.

                  Subject to  payment by the Issuer of a sum suffi  cient to pay
the amount due on  redemption,  interest  and  Original  Issue  Discount on this
Security (or portion hereof if this Security is redeemed in part) shall cease to
accrue  upon the date duly fixed for  redemption  of this  Security  (or portion
hereof if this Security is redeemed in part).

                  Subject  to the terms and  conditions  of the  Indenture,  the
Issuer shall become  obligated  to  purchase,  at the option of the Holder,  the
Securities  held by such Holder on October 22, 2003 (the  "Repurchase  Date") at
the Repurchase  Price of $802.93 per $1,000  principal  amount thereof (equal to
the Issue Price  thereof plus accrued  Original  Issue  Discount  thereon to the
Repurchase Date), plus accrued and unpaid interest,  if any, up to but excluding
the  Repurchase  Date,  upon  delivery of a  Repurchase  Notice  containing  the
information set forth in the Indenture, at any time from the opening of business
on the date that is 20  Business  Days  prior to the  Repurchase  Date until the
close of business on the Repurchase  Date and upon delivery of the Securities to
the Paying Agent by the Holder as set forth in the Indenture.

                  The Repurchase Price may be paid, at the option of the Issuer,
in cash or by the issuance and delivery of shares of Class A Common Stock of the
Issuer, or in any combination thereof.

                  Holders  have the right to withdraw any  Repurchase  Notice by
delivering to the Paying Agent a written notice of

                                      -11-
<PAGE>

withdrawal in accordance with the provisions of the Indenture.

                  If cash (and/or  securities if permitted  under the Indenture)
sufficient to pay the Repurchase  Price of all Securities or portions thereof to
be  purchased as of the  Repurchase  Date,  is  deposited  with the Trustee or a
Paying Agent on the Repurchase Date, interest and Original Issue Discount ceases
to accrue on such  Securities  (or  portions  thereof)  immediately  after  such
Repurchase  Date,  and the Holder  thereof  shall  have no other  rights as such
(other than the right to receive the  Repurchase  Price upon  surrender  of such
Security).

                  The  Holder  of this  Security  and the  Class A Common  Stock
issuable on the conversion  hereof is entitled to the benefits of a Registration
Rights  Agreement  executed by the Issuer.  Whenever in this Security there is a
reference  to the  payment of interest  on, or in respect  of, a Security,  such
mention shall be deemed to include mention of the payment of liquidated  damages
to the extent payable as contemplated in such Registration Rights Agreement.

                  The Issuer, the Trustee and any authorized agent of the Issuer
or the Trustee may deem and treat the  registered  Holder hereof as the absolute
owner of this  Security  (whether  or not this  Security  shall be  overdue  and
notwithstanding any notation of ownership or other writing hereon made by anyone
other than the Issuer or the  Trustee or any  authorized  agent of the Issuer or
the  Trustee),  for the purpose of  receiving  payment of, or on account of, the
principal  hereof,  accrued Original Issue Discount hereon and premium,  if any,
and,  subject to the provisions on the face hereof,  interest hereon and for all
other purposes,  and neither the Issuer nor the Trustee nor any authorized agent
of the Issuer or the Trustee shall be affected by any notice to the contrary.

                  No recourse  shall be had for the payment of the  principal of
or  premium,  if any,  or the  interest  on this  Security,  for any claim based
hereon,  or  otherwise  in  respect  hereof,  or based on or in  respect  of the
Indenture

                                      -12-
<PAGE>

or any indenture  supplemental  thereto,  against any incorporator,  as such, or
against any past, present or future stockholder,  officer or director,  as such,
of the Issuer or of any  partner  or member of the  Issuer or of any  successor,
either directly or through the Issuer or any successor, whether by virtue of any
constitution,  statute or rule of law or by the enforcement of any assessment or
penalty or otherwise, all such liability being, by the acceptance thereof and as
part of the consideration for the issue hereof, expressly waived and released.

                  The  Indenture  and this  Security  shall be  governed  by and
construed in accordance with the laws of the State of New York.



                                      -13-
<PAGE>




                [FORM OF TRUSTEE'S CERTIFICATE OF AUTHENTICATION]


                  This   is   one   of   the   Securities   described   in   the
within-mentioned Indenture.


                                            THE BANK OF NEW YORK,
                                            as Trustee



                                            __________________________
                                            Authorized Signatory




                                      -14-
<PAGE>




                           [FORM OF CONVERSION NOTICE]

                  To:      American Tower Corporation

                  The undersigned owner of this Security hereby: (i) irrevocably
exercises  the option to convert  this  Security,  or the portion  hereof  below
designated,  for shares of Class A Common Stock of American Tower Corporation in
accordance with the terms of the Indenture referred to in this Security and (ii)
directs  that  such  shares  of  Class  A  Common  Stock  deliverable  upon  the
conversion,  together  with any check in payment for  fractional  shares and any
Security(ies)  representing any unconverted  principal amount hereof,  be issued
and delivered to the  registered  Holder hereof unless a different name has been
indicated below. If shares and/or  Security(ies) are to be delivered  registered
in the name of a person other than the undersigned, the undersigned will pay all
transfer taxes payable with respect  thereto.  Any amount required to be paid by
the undersigned on account of interest accompanies this Security.

Dated:

                                            __________________________
                                                   Signature

Fill in for  registration of shares if to be delivered,  and of Securities if to
be issued, otherwise than to and in the name of the registered Holder.


                                            __________________________
                                             Social Security or Other
                                            Taxpayer Identifying Number

_______________________________________
         (Name)

_______________________________________
         (Street Address)

_______________________________________
         (City, State and Zip Code)
         (Please print name and address)

                                            Principal Amount to Be Converted:
                                                     (if less than all)

                                            $_____________________________


                                      -15-
<PAGE>



                  [FORM OF OPTION OF HOLDER TO ELECT REDEMPTION
                             UPON CHANGE IN CONTROL]

                  If you want to elect to have this  Security  purchased  in its
entirety by the Issuer pursuant to Article Thirteen of the Indenture,  check the
box:

                 / /

                  If you  want to  elect  to have  only a part of this  Security
purchased by the Issuer pursuant to Article Thirteen of the Indenture, state the
principal amount:
$


Dated:                                      Your Signature:____________________
                                            (Sign exactly as name appears
                                            on the face of this Security)


Signature
                                    Guarantee:__________________________________
                                    (Signature  must be  guaranteed  by a member
                                    firm of the New  York  Stock  Exchange  or a
                                    commercial bank or trust company)



                                      -16-

                                                                     EXHIBIT 4.5




                          REGISTRATION RIGHTS AGREEMENT




                           Dated as of October 4, 1999


                                      Among


                           AMERICAN TOWER CORPORATION

                                    as Issuer

                                       and


                     CREDIT SUISSE FIRST BOSTON CORPORATION
                          DEUTSCHE BANK SECURITIES INC.
                              LEHMAN BROTHERS INC.
                        MORGAN STANLEY & CO. INCORPORATED
                         BANC OF AMERICA SECURITIES LLC
                            BEAR, STEARNS & CO. INC.
                              GOLDMAN, SACHS & CO.
               MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED
                            SALOMON SMITH BARNEY INC.

                              as Initial Purchasers


<PAGE>
<TABLE>
<CAPTION>

                                             TABLE OF CONTENTS

                                                                                                      Page
<S>     <C>                                                                                            <C>

1.       Definitions.....................................................................................1

2.       Shelf Registration..............................................................................5

3.       Additional Interest.............................................................................7

4.       Registration Procedures.........................................................................9

5.       Registration Expenses..........................................................................19

6.       Indemnification................................................................................20

7.       Rules 144 and 144A.............................................................................24

8.       Underwritten Registrations.....................................................................24

9.       Representations and Warranties.................................................................25

10.      Miscellaneous..................................................................................27
         (a)      No Inconsistent Agreements............................................................27
         (b)      Adjustments Affecting Registrable
                  Securities............................................................................27
         (c)      Amendments and Waivers................................................................27
         (d)      Notices...............................................................................28
         (e)      Successors and Assigns................................................................29
         (f)      Counterparts..........................................................................29
         (g)      Headings..............................................................................29
         (h)      Governing Law.........................................................................29
         (i)      Severability..........................................................................30
         (j)      Securities Held by the Company or Its
                  Affiliates............................................................................30
         (k)      Third Party Beneficiaries.............................................................30
         (l)      Entire Agreement......................................................................30

</TABLE>
                                                    -i-
<PAGE>

                          REGISTRATION RIGHTS AGREEMENT


         This  Registration  Rights  Agreement (the  "Agreement") is dated as of
October 4, 1999, among American Tower Corporation,  a Delaware  corporation (the
"Company"), and Credit Suisse First Boston Corporation, Deutsche Bank Securities
Inc., Lehman Brothers Inc., Morgan Stanley & Co.  Incorporated,  Banc of America
Securities LLC, Bear, Stearns & Co. Inc.,  Goldman,  Sachs & Co., Merrill Lynch,
Pierce, Fenner & Smith Incorporated and Salomon Smith Barney Inc. (individually,
an "Initial Purchaser"; together, the "Initial Purchasers").

         This  Agreement  is  entered  into  in  connection  with  the  Purchase
Agreement,  dated  September  28,  1999,  between  the  Company  and the Initial
Purchasers (the "Purchase Agreement"),  which provides for the issuance and sale
by the Company to the Initial  Purchasers  of the  Company's  6.25%  Convertible
Notes  Due 2009  ("Standard  Notes")  and its 2.25%  Convertible  Notes Due 2009
("Discount  Notes" and,  collectively,  the  "Convertible  Notes").  In order to
induce the Initial Purchasers to enter into the Purchase Agreement,  the Company
has agreed to provide the  registration  rights set forth in this  Agreement for
the benefit of the Initial Purchasers and their direct and indirect  transferees
and assigns.  The execution and delivery of this Agreement is a condition to the
Initial  Purchasers'  obligation  to purchase  the  Convertible  Notes under the
Purchase Agreement.

         The parties hereby agree as follows:

         1.       Definitions.

         As used in this Agreement, the following terms shall have the following
meanings:

         Additional Interest:  See Section 3(a) hereof.

         Advice:  See Section 4 hereof.

<PAGE>

         Agreement: See the first introductory paragraph hereto.

         Amount of  Registrable  Securities:  (a) With respect to Standard Notes
constituting Registrable Securities,  their aggregate principal amount, (b) with
respect to Discount Notes  constituting  Registrable  Securities,  the aggregate
Issue Price (as defined in the Discount  Indenture) of such Discount  Notes plus
the accrued  Original  Issue  Discount  (as defined in the  Discount  Indenture)
thereon through the time of computing the Amount of Registrable Securities,  (c)
with respect to  Underlying  Shares  constituting  Registrable  Securities,  the
aggregate  number of such Underlying  Shares  multiplied by the Conversion Price
(as  defined  in the  Indenture  relating  to the  Convertible  Notes  upon  the
conversion of which such Underlying Shares were issued) in effect at the time of
computing the Amount of Registrable  Securities or, if no such Convertible Notes
are then  outstanding,  the last Conversion  Price that was in effect under such
Indenture when any such Convertible  Notes were last  outstanding,  and (d) with
respect to  combinations  thereof,  the sum of (a), (b) and (c) for the relevant
Registrable Securities.

         Certificate Shares:  See Section 9 hereof.

         Closing Date: A Closing Date as defined in the Purchase Agreement.

         Company:  See the first introductory paragraph hereto.

         Convertible Notes: See the second introductory paragraph hereto.

         Damages Payment Date:  See Section 3(c) hereof.

         Depositary: The Depository Trust Company until a successor is appointed
by the Company.

         Discount Indenture: The Indenture, dated as of October 4, 1999, between
the Company and The Bank of New

                                       -2-
<PAGE>

York, as Trustee, pursuant to which the Discount Notes are issued, as amended or
supplemented from time to time.

         Discount Notes: See the second introductory paragraph hereto.

         Effectiveness Date: The 150th day after the Issue Date.

         Effectiveness Period:  See Section 2 hereof.

         Exchange Act: The Securities Exchange Act of 1934, as amended,  and the
rules and regulations of the SEC promul gated thereunder.

         Filing Date:  The 90th day after the Issue Date.

         Global Certificate:  See Section 9 hereof.

         Holder: Any holder of Registrable Securities.

         Indemnified Person:  See Section 6(c) hereof.

         Indemnifying Person:  See Section 6(c) hereof.

         Indenture:  The Standard Indenture or the Discount Indenture,  or both,
as the context requires.

         Initial Purchaser: See the first introductory paragraph hereto.

         Initial Purchasers: See the first introductory paragraph hereto.

         Initial Shelf Registration:  See Section 2(a) hereof.

         Inspectors:  See Section 4(n) hereof.

         Issue Date: The latest Closing Date on which the Convertible Notes were
issued and sold to the Initial Purchasers pursuant to the Purchase Agreement.

                                       -3-
<PAGE>

         NASD:  See Section 4(q) hereof.

         Participant:  See Section 6(a) hereof.

         Person:  An individual,  partnership,  corporation,  limited  liability
company,  unincorporated association,  trust or joint venture, or a governmental
agency or political subdivision thereof.

         Prospectus:  The  prospectus  included in any Registra  tion  Statement
(including,  without  limitation,  any  prospectus  subject to completion  and a
prospectus  that includes any information  previously  omitted from a prospectus
filed as part of an effective  registration statement in reliance upon Rule 430A
promulgated  under the  Securities  Act),  as  amended  or  supplemented  by any
prospectus  supplement,   and  all  other  amendments  and  supplements  to  the
Prospectus,  including post-effective  amendments, and all material incorporated
by reference or deemed to be incorporated by reference in such Prospectus.

         Purchase Agreement: See the second introductory paragraph hereto.

         Records:  See Section 4(n) hereof.

         Registrable Securities: All Convertible Notes and all Underlying Shares
upon original  issuance  thereof and at all times  subsequent  thereto until the
earliest to occur of (i) a  Registration  Statement  covering  such  Convertible
Notes and  Underlying  Shares has been  declared  effective  by the SEC and such
Convertible Notes and Underlying Shares have been disposed of in accordance with
such  effective  Registration   Statement,   (ii)  such  Convertible  Notes  and
Underlying  Shares are sold in  compliance  with Rule 144 or could  (except with
respect to affiliates of the Company within the meaning of the  Securities  Act)
be sold in  compliance  with  paragraph  (k) of such  Rule  144,  or (iii)  such
Convertible Notes and any Underlying Shares cease to be outstanding.

         Registration Default:  See Section 3(a) hereof.

                                       -4-
<PAGE>

         Registration Statement: Any registration statement of the Company filed
with  the SEC  pursuant  to the  provisions  of this  Agreement,  including  the
Prospectus, amendments and supplements to such registration statement, including
post-effective  amendments,  all  exhibits  and all  material  incorpo  rated by
reference  or  deemed  to be  incorporated  by  reference  in such  registration
statement.

         Rule 144: Rule 144  promulgated  under the Securities Act, as such Rule
may be amended from time to time,  or any similar rule (other than Rule 144A) or
regulation  hereafter  adopted  by the SEC  providing  for  offers  and sales of
securities  made in  compliance  therewith  resulting  in  offers  and  sales by
subsequent holders that are not affiliates of an issuer of such securities being
free of the registration and prospectus delivery  requirements of the Securities
Act.

         Rule 144A: Rule 144A promulgated under the Securities Act, as such Rule
may be amended  from time to time,  or any similar rule (other than Rule 144) or
regulation hereafter adopted by the SEC.

         Rule 415: Rule 415  promulgated  under the Securities Act, as such Rule
may be amended from time to time,  or any similar rule or  regulation  hereafter
adopted by the SEC.

         SEC:  The Securities and Exchange Commission.

         Securities  Act: The Securities Act of 1933, as amended,  and the rules
and regulations of the SEC promulgated thereunder.

         Shelf Registration:  See Section 2(b) hereof.

         Standard Indenture: The Indenture, dated as of October 4, 1999, between
the Company and The Bank of New York, as Trustee, pursuant to which the Standard
Notes are issued, as amended or supplemented from time to time.

         Standard Notes: See the second introductory paragraph hereto.

                                      -5-
<PAGE>

         Subsequent Shelf Registration: See Section 2(b) hereof.

         TIA: The Trust  Indenture  Act of 1939,  as amended,  and the rules and
regulations of the SEC promulgated thereunder.

         Trustee:  The Trustee under the Indenture.

         Underlying  Shares:  The shares of the Company's  Class A Common Stock,
par value $.01 per share, issuable upon conversion of the Convertible Notes.

         Underwritten  registration or underwritten  offering: A registration in
which securities of the Company are sold to an underwriter for reoffering to the
public.

         2.       Shelf Registration

                           (a)      Shelf  Registration.  The  Company  shall as
                                    promptly as reasonably practicable file with
                                    the  SEC a  Registration  Statement  for  an
                                    offering  to be made on a  continuous  basis
                                    pursuant  to Rule  415  covering  all of the
                                    Registrable  Securities  (the "Initial Shelf
                                    Registration").  The  Company  shall use its
                                    reasonable best efforts to file with the SEC
                                    the Initial Shelf  Registration  on or prior
                                    to  the  Filing  Date.   The  Initial  Shelf
                                    Registration shall be on Form S-3 or another
                                    appropriate form permitting  registration of
                                    such  Registrable  Securities  for resale by
                                    Holders in the manner or manners  designated
                                    by them (including,  without limitation, one
                                    or more underwritten offerings). The Company
                                    shall not permit any  securities  other than
                                    the Registrable Securities to be included in
                                    the Initial Shelf

                                       -6-

<PAGE>

                                    Registration   or   any   Subsequent   Shelf
                                    Registration  (as  defined  below).  By  its
                                    execution hereof on behalf of itself and the
                                    other  Initial  Purchasers,   Credit  Suisse
                                    First Boston  Corporation also hereby waives
                                    on  its  own  behalf  its  right  under  the
                                    Registration    Rights   Agreement,    dated
                                    February  4, 1999,  between  the Company and
                                    it,  to   include   any   securities   in  a
                                    Registration  Statement  filed  pursuant  to
                                    this Agreement.

         The Company shall use its reasonable  best efforts to cause the Initial
Shelf Registration to be declared effective under the Securities Act on or prior
to  the  Effectiveness   Date  and  to  keep  the  Initial  Shelf   Registration
continuously effective under the Securities Act until the date that is 24 months
from the Issue  Date (as it may be  shortened  pursuant  to clause (i) or clause
(ii) immediately following,  the "Effectiveness Period"), or such shorter period
ending when (i) all the shares of Registrable  Securities covered by the Initial
Shelf Registration have been sold in the manner set forth and as contemplated in
the  Initial  Shelf  Registration,  (ii) the date on which  all the  Registrable
Securities  (x) held by persons  who are not  affiliates  of the  Company may be
resold  pursuant  to Rule  144(k)  under the  Securities  Act or (y) cease to be
outstanding,  or  (iii) a  Subsequent  Shelf  Registration  covering  all of the
Registrable Securities has been declared effective under the Securities Act.

                           (b)      Subsequent  Shelf   Registrations.   If  the
                                    Initial Shelf Registration or any Subsequent
                                    Shelf  Registration  ceases to be  effective
                                    for  any  reason  at  any  time  during  the
                                    Effectiveness  Period (other than because of
                                    the sale of all of the securities registered
                                    thereunder),

                                       -7-

<PAGE>

                                    the Company  shall use its  reasonable  best
                                    efforts to obtain the prompt  withdrawal  of
                                    any  order   suspending  the   effectiveness
                                    thereof,  and in any event  shall  within 45
                                    days  of  such  cessation  of  effectiveness
                                    amend the Initial  Shelf  Registration  in a
                                    manner to obtain the withdrawal of the order
                                    suspending  the  effectiveness  thereof,  or
                                    file  an  additional  "shelf"   Registration
                                    Statement  pursuant to Rule 415 covering all
                                    of the Registrable Securities (a "Subsequent
                                    Shelf Registration").  If a Subsequent Shelf
                                    Registration is filed, the Company shall use
                                    its  reasonable  best  efforts  to cause the
                                    Subsequent Shelf Registration to be declared
                                    effective  under the  Securities Act as soon
                                    as practicable after such filing and to keep
                                    such  Registration   Statement  continuously
                                    effective   for   the   remainder   of   the
                                    Effectiveness  Period.  As used  herein  the
                                    term "Shelf  Registration" means the Initial
                                    Shelf  Registration and any Subsequent Shelf
                                    Registration.

                           (c)      Supplements  and  Amendments.   The  Company
                                    shall  promptly  supplement  and  amend  the
                                    Shelf Registration if required by the rules,
                                    regulations  or  instructions  applicable to
                                    the  registration  form used for such  Shelf
                                    Registration,  if required by the Securities
                                    Act,  or  if  reasonably  requested  by  the
                                    Holders  of a  majority  of  the  Amount  of
                                    Registrable   Securities   covered  by  such
                                    Registration Statement or

                                      -8-
<PAGE>

                                    by  any  underwriter  of  such   Registrable
                                    Securities.

         3.       Additional Interest

                           (a)      The Company and the Initial Purchasers agree
                                    that the Holders of  Convertible  Notes will
                                    suffer  damages  if  the  Company  fails  to
                                    fulfill  its  obligations  under  Section  2
                                    hereof and that it would not be  feasible to
                                    ascertain  the extent of such  damages  with
                                    precision.  Accordingly,  the Company agrees
                                    to pay, as  liquidated  damages,  additional
                                    interest  on  the   Registrable   Securities
                                    ("Additional Interest") as follows if any of
                                    the following  events occur (each such event
                                    in  clauses  (i)   through   (iii)  below  a
                                    "Registration Default"):

         (i)      If  on  or  prior  to  the  Filing  Date,  the  Initial  Shelf
                  Registration has not been filed with the SEC;

         (ii)     If on or prior to the  Effectiveness  Date,  the Initial Shelf
                  Registration has not been declared effective by the SEC; or

         (iii)    If after the Initial Shelf  Registration is declared effective
                  (A) the Initial  Shelf  Registration  thereafter  ceases to be
                  effective  and a Subsequent  Shelf  Registration  covering the
                  Registrable Securities has not become effective or (B) a Shelf
                  Registration  or the  related  prospectus  ceases to be usable
                  (except as permitted  in Section  3(b)  hereof) in  connection
                  with  resales of  Registrable  Securities  during the  periods
                  specified  herein  because  either  (1) any event  occurs as a
                  result of which the

                                      -9-
<PAGE>


                  related  prospectus  forming  part of such Shelf  Registration
                  would include any untrue  statement of a material fact or omit
                  to state any material  fact  necessary to make the  statements
                  therein  in the light of the  circumstances  under  which they
                  were  made not  misleading,  or (2) it shall be  necessary  to
                  amend  such  Shelf  Registration  or  supplement  the  related
                  prospectus,  to comply with the Securities Act or the Exchange
                  Act or the respective rules thereunder.

         Additional  Interest  shall  accrue on  outstanding  Convertible  Notes
constituting Registrable Securities over and above the interest set forth in the
title of the Convertible Notes and shall accrue on outstanding Underlying Shares
constituting Registrable Securities, in each case from and including the date on
which any such  Registration  Default  shall occur to but  excluding the date on
which all such  Registration  Defaults  have been cured,  at a rate of 0.50% per
annum of the Amount of such Registrable Securities. The Company shall notify the
Trustee  within  one  business  day  after  each  and  every  date  on  which  a
Registration Default occurs.

                           (b)      A  Registration   Default   referred  to  in
                                    Section  3(a)(iii)(B) hereof shall be deemed
                                    not to have  occurred and be  continuing  in
                                    relation  to the Shelf  Registration  or the
                                    related  prospectus if (i) such Registration
                                    Default has  occurred  solely as a result of
                                    (x) the filing of a post-effective amendment
                                    to such Shelf  Registration  to  incorporate
                                    annual audited  financial  information  with
                                    respect   to   the   Company    where   such
                                    post-effective    amendment   is   not   yet
                                    effective and needs to be declared effective
                                    to  permit   Holders  to  use  the   related
                                    prospectus or (y) other material events with
                                    respect to the

                                      -10-
<PAGE>


                                    Company  that would need to be  described in
                                    such  Shelf   Registration  or  the  related
                                    prospectus  and (ii) in the  case of  clause
                                    (y), the Company is proceeding  promptly and
                                    in good  faith to amend or  supplement  such
                                    Shelf Registration and related prospectus to
                                    describe  such  events;  provided,  however,
                                    that  in  any  case  if  such   Registration
                                    Default  occurs for a  continuous  period in
                                    excess of 30 days, Additional Interest shall
                                    be payable in  accordance  with Section 3(a)
                                    hereof   from  the  day  such   Registration
                                    Default   occurs  until  such   Registration
                                    Default is cured.

                           (c)      Any  amount  of   Additional   Interest  due
                                    pursuant  to  clause  (i),  (ii) or (iii) of
                                    Section  3(a) hereof will be payable in cash
                                    on each April 15 and  October 15 (a "Damages
                                    Payment Date") to the Holder to whom regular
                                    interest is payable on such Damages  Payment
                                    Date with respect to Convertible  Notes that
                                    are Registrable Securities and to the Person
                                    that is a registered Holder 15 days prior to
                                    such  Damages  Payment  Date with respect to
                                    Underlying   Shares  that  are   Registrable
                                    Securities.   The   amount   of   Additional
                                    Interest for Registrable  Securities will be
                                    determined  by  multiplying  the  applicable
                                    Additional  Interest  rate by the  Amount of
                                    such  Registrable  Securities on the Damages
                                    Payment  Date  following  such  Registration

                                      -11-
<PAGE>

                                    Default  in  the  case  of  the  first  such
                                    payment of Additional  Interest with respect
                                    to a Registration Default (and thereafter at
                                    the next  succeeding  Damages  Payment  Date
                                    until   the   cure  of   such   Registration
                                    Default),  multiplied  by  a  fraction,  the
                                    numerator  of  which is the  number  of days
                                    such Additional Interest rate was applicable
                                    during such period  (determined on the basis
                                    of a 360-day year comprised of twelve 30-day
                                    months),  and the  denominator  of  which is
                                    360.

         4.       Registration Procedures

         In connection with the filing of any Registration Statement pursuant to
Section 2 hereof, the Company shall effect such registrations to permit the sale
of the  securities  covered  thereby in accordance  with the intended  method or
methods of disposition  thereof, and pursuant thereto and in connection with any
Registration Statement filed by the Company hereunder the Company shall:

                           (a)      Prepare  and file  with the SEC prior to the
                                    Filing  Date,  a  Registration  Statement or
                                    Registration  Statements  as  prescribed  by
                                    Section  2  hereof,  and use its  reasonable
                                    best efforts to cause each such Registration
                                    Statement  to become  effective  and  remain
                                    effective  as  provided  herein;   provided,
                                    however,  that the Company  shall furnish to
                                    and  afford the  Holders of the  Registrable
                                    Securities   covered  by  such  Registration
                                    Statement,  their  counsel and the  managing
                                    underwriters,    if   any,   a    reasonable
                                    opportunity to review copies of all


                                       -12-

<PAGE>

                                    such  documents  (including  copies  of  any
                                    documents  to be  incorporated  by reference
                                    therein and all exhibits  thereto)  proposed
                                    to be filed (in each case where  possible at
                                    least  five  business  days  prior  to  such
                                    filing and where not possible as promptly as
                                    possible).  The  Company  shall not file any
                                    Registration Statement or Pro spectus or any
                                    amendments  or  supplements  thereto  if the
                                    Holders  of a  majority  in  Amount  of  the
                                    Registrable   Securities   covered  by  such
                                    Registration  Statement,  their counsel,  or
                                    the  managing  underwriters,  if any,  shall
                                    reasonably object.

                           (b)      Prepare   and   file   with   the  SEC  such
                                    amendments and post-effective  amendments to
                                    each Shelf Registration, as may be necessary
                                    to   keep   such   Registration    Statement
                                    continuously effective for the Effectiveness
                                    Period;  cause the related  Prospectus to be
                                    supplemented  by any  Prospectus  supplement
                                    required  by  applicable   law,  and  as  so
                                    supplemented  to be filed  pursuant  to Rule
                                    424  (or  any  similar  provisions  then  in
                                    force) promulgated under the Securities Act;
                                    and comply with the  provisions  of the Secu
                                    rities Act and the Exchange  Act  applicable
                                    to it with respect to the disposition of all
                                    securities   covered  by  such  Registration
                                    Statement   as  so   amended   or  in   such
                                    Prospectus as so  supplemented.  The Company
                                    shall be deemed not to have used its


                                      -13-
<PAGE>

                                    reasonable    best   efforts   to   keep   a
                                    Registration  Statement effective during the
                                    Effectiveness Period if it voluntarily takes
                                    any  action  that  would  result in  selling
                                    Holders   of  the   Registrable   Securities
                                    covered  thereby not being able to sell such
                                    Registrable  Securities  during  that period
                                    unless such action is required by applicable
                                    law or unless the Company complies with this
                                    Agreement,  including without limitation the
                                    provisions  of Section  4(k)  hereof and the
                                    last paragraph of Section 4(t) hereof.

                           (c)      Notify  the  selling  Holders  of  shares of
                                    Registrable  Securities,  their  counsel and
                                    the managing underwriters,  if any, promptly
                                    (but in any event within two business days),
                                    and confirm such notice in writing, (i) when
                                    a Prospectus or any prospectus supplement or
                                    post-effective  amendment  has  been  filed,
                                    and,   with  respect  to  a  Reg   istration
                                    Statement or any  post-effective  amendment,
                                    when the same has become effective under the
                                    Securities  Act  (including in such notice a
                                    written  statement that any Holder may, upon
                                    request,  obtain, at the sole expense of the
                                    Company,   one   conformed   copy   of  such
                                    Registration   Statement  or  post-effective
                                    amendment including financial statements and
                                    schedules,  documents incorporated or deemed
                                    to  be   incorporated   by   reference   and
                                    exhibits),  (ii) (A) of the  receipt  of any
                                    written comments by the SEC

                                      -14-

<PAGE>


                                    or its staff,  (B) of the request by the SEC
                                    or its staff for  amendments or  supplements
                                    to a Registration Statement or a Prospectus,
                                    or  (C) of the  issuance  by the  SEC of any
                                    stop order suspending the effectiveness of a
                                    Registration   Statement  or  of  any  order
                                    preventing  or  suspending  the  use  of any
                                    preliminary  prospectus or the initiation of
                                    any proceedings  for that purpose,  (iii) if
                                    at any time when a prospectus is required by
                                    the   Securities  Act  to  be  delivered  in
                                    connection  with  sales  of the  Registrable
                                    Securities    the     representations    and
                                    warranties  of the Company  contained in any
                                    agreement    (including   any   underwriting
                                    agreement),  contemplated  by  Section  4(m)
                                    hereof  cease to be true and  correct in all
                                    material respects,  (iv) of the happening of
                                    any event, the existence of any condition or
                                    any  information  becoming  known that makes
                                    any  statement  made  in  such  Registration
                                    Statement  or  related   Prospectus  or  any
                                    document   incorporated   or  deemed  to  be
                                    incorporated  therein by reference untrue in
                                    any  material  respect or that  requires the
                                    making of any  changes in or  amendments  or
                                    supplements to such Registration  Statement,
                                    Prospectus or documents so that, in the case
                                    of the Registration  Statement,  it will not
                                    contain any untrue  statement  of a material
                                    fact or  omit to  state  any  material  fact
                                    required to be stated  therein or  necessary
                                    to   make   the

                                      -15-
<PAGE>

                                    statements therein not misleading,  and that
                                    in the case of the  Prospectus,  it will not
                                    contain any untrue  statement  of a material
                                    fact or  omit to  state  any  material  fact
                                    required to be stated  therein or  necessary
                                    to make the statements therein, in the light
                                    of the  circumstances  under which they were
                                    made,   not   misleading   and  (v)  of  the
                                    Company's      determination      that     a
                                    post-effective  amendment to a  Registration
                                    Statement would be appropriate.

                           (d)      Use its  reasonable  best efforts to prevent
                                    the  issuance  of any order  suspending  the
                                    effectiveness of a Registration Statement or
                                    of any order  preventing or  suspending  the
                                    use of a  Prospectus  and, if any such order
                                    is  issued,   to  use  its  reasonable  best
                                    efforts to obtain the withdrawal of any such
                                    order at the earliest possible moment.

                           (e)      If requested by the managing  underwriter or
                                    underwriters  (if any),  or the Holders of a
                                    majority   in  Amount  of  the   Registrable
                                    Securities  being sold in connection with an
                                    underwritten    offering,    (i)    promptly
                                    incorporate  in a prospectus  supplement  or
                                    post-effective amendment such information as
                                    the managing underwriter or underwriters (if
                                    any),  such  Holders or  counsel  for any of
                                    them determine is reasonably necessary to be
                                    included  therein,  (ii)  make all  required
                                    filings of


                                      -16-

<PAGE>

                                    such    prospectus    supplement   or   such
                                    post-effective    amendment   as   soon   as
                                    reasonably practicable after the Company has
                                    received  notification  of the matters to be
                                    incorporated in such  prospectus  supplement
                                    or   post-effective   amendment   and  (iii)
                                    supplement   or  make   amendments  to  such
                                    Registration Statement.

                           (f)      Furnish   to   each   selling    Holder   of
                                    Registrable  Securities  and to counsel  and
                                    each  managing  underwriter,  if any, at the
                                    sole expense of the Company,  one  conformed
                                    copy  of  the   Registration   Statement  or
                                    Registration     Statements     and     each
                                    post-effective amendment thereto,  including
                                    financial statements and schedules,  and, if
                                    requested,  all  documents  incorporated  or
                                    deemed  to  be   incorporated   therein   by
                                    reference and all exhibits.

                           (g)      Deliver   to   each   selling    Holder   of
                                    Registrable  Securities,   their  respective
                                    counsel,  and the  underwriters,  if any, at
                                    the sole  expense  of the  Company,  as many
                                    copies  of the  Prospectus  (including  each
                                    form of  preliminary  prospectus)  and  each
                                    amendment  or  supplement  thereto  and  any
                                    documents  incorporated by reference therein
                                    as such Persons may reasonably request; and,
                                    subject to the second  paragraph  of Section
                                    4(t) hereof,  the Company hereby consents to
                                    the  use  of  such   Prospectus   and   each
                                    amendment or  supplement  thereto by each of
                                    the

                                      -17-
<PAGE>


                                    selling  Holders of  Registrable  Securities
                                    and the underwriters or agents,  if any, and
                                    dealers  (if any),  in  connection  with the
                                    offering   and   sale  of  the   Registrable
                                    Securities  covered by such  Prospectus  and
                                    any amendment or supplement thereto.

                           (h)      Prior to any public  offering of Registrable
                                    Securities,   to  use  its  reasonable  best
                                    efforts  to  register  or  qualify,  to  the
                                    extent  required by  applicable  law, and to
                                    cooperate   with  the  selling   Holders  of
                                    Registrable    Securities,    the   managing
                                    underwriter  or  underwriters,  if any,  and
                                    their respective  counsel in connection with
                                    the   registration  or   qualification   (or
                                    exemption   from   such    registration   or
                                    qualification)     of    such    Registrable
                                    Securities  or  offer  and  sale  under  the
                                    securities   or  Blue   Sky   laws  of  such
                                    jurisdictions  within the  United  States as
                                    any   selling   Holder,   or  the   managing
                                    underwriter   or   underwriters   reasonably
                                    request;   provided,   however,  that  where
                                    Registrable  Securities  are  offered  other
                                    than through an underwritten  offering,  the
                                    Company   agrees  to  cause  the   Company's
                                    counsel to perform  Blue Sky  investigations
                                    and file  registrations  and  qualifications
                                    required  to  be  filed   pursuant  to  this
                                    Section 4(h); keep each such registration or
                                    qualification   (or   exemption   therefrom)
                                    effective    during    the    period    such
                                    Registration Statement

                                      -18-
<PAGE>

                                    is required to be kept  effective and do any
                                    and  all  other  acts or  things  reasonably
                                    necessary   or   advisable   to  enable  the
                                    disposition  in  such  jurisdictions  of the
                                    Registrable   Securities   covered   by  the
                                    applicable Registration Statement; provided,
                                    however,  that  the  Company  shall  not  be
                                    required to qualify as a foreign corporation
                                    or to  execute a general  consent to service
                                    of  process in any  jurisdiction  or subject
                                    itself   to   taxation   generally   in  any
                                    jurisdiction.

                           (i)      Cooperate   with  the  selling   Holders  of
                                    Registrable   Securities  and  the  managing
                                    underwriter  or  underwriters,  if  any,  to
                                    facilitate   the  timely   preparation   and
                                    delivery of certificates representing shares
                                    of Registrable  Securities to be sold, which
                                    certificates  shall not bear any restrictive
                                    legends and shall be in a form  eligible for
                                    deposit with The  Depository  Trust Company;
                                    and  enable  such   shares  of   Registrable
                                    Securities to be in such  denominations  and
                                    registered  in such  names  as the  managing
                                    underwriter  or  underwriters,  if  any,  or
                                    Holders may reasonably request.

                           (j)      Use its reasonable best efforts to cause the
                                    Registrable  Securities covered by the Shelf
                                    Registration Statement to be registered with
                                    or  approved  by  such  other   governmental
                                    agencies or  authorities as may be necessary
                                    to

                                      -19-
<PAGE>

                                    enable the seller or sellers  thereof or the
                                    underwriter  or  underwriters,  if  any,  to
                                    consummate    the    disposition   of   such
                                    Registrable  Securities,  except  as  may be
                                    required  solely  as a  consequence  of  the
                                    nature of such selling Holder's business, in
                                    which case the Company will cooperate in all
                                    reasonable  respects with the filing of such
                                    Registration  Statement  and the granting of
                                    such approvals.

                           (k)      Upon   the    occurrence    of   any   event
                                    contemplated   by   paragraph   4(c)(ii)(C),
                                    4(c)(iv) or 4(c)(v)  hereof,  as promptly as
                                    practicable  prepare and (subject to Section
                                    4(a)  hereof) file with the SEC, at the sole
                                    expense  of the  Company,  a  supplement  or
                                    post-effective amendment to the Registration
                                    Statement  or a  supplement  to the  related
                                    Prospectus or any document  incorporated  or
                                    deemed  to  be   incorporated   therein   by
                                    reference,   or  file  any  other   required
                                    document so that, as thereafter delivered to
                                    the purchasers of the Registrable Securities
                                    being sold  thereunder,  any such Prospectus
                                    will not  contain an untrue  statement  of a
                                    material  fact or omit to  state a  material
                                    fact  required  to  be  stated   therein  or
                                    necessary to make the statements therein, in
                                    the light of the  circumstances  under which
                                    they were made,  not  misleading;  provided,
                                    however,   that  the   Company   may   delay
                                    preparing,  filing and distributing any such
                                    supplement or amendment (and continue the

                                      -20-
<PAGE>


                                    suspension of the use of the  Prospectus) if
                                    the  Company  determines  in good faith that
                                    such  supplement or amendment  would, in the
                                    reasonable  judgment  of  the  Company,  (i)
                                    interfere with or affect the  negotiation or
                                    completion  of a  transaction  that is being
                                    contemplated by the Company  (whether or not
                                    a final  decision has been made to undertake
                                    such transaction) or (ii) involve initial or
                                    continuing  disclosure  obligations that are
                                    not in the best  interests of the  Company's
                                    shareholders   at   such   time;   provided,
                                    further,  that  neither  such delay nor such
                                    suspension  with  respect to all  matters in
                                    clause (i) or (ii) shall extend for a period
                                    of more  than  30  days  in any  three-month
                                    period  or more  than 90 days  for all  such
                                    periods in any twelve-month period and shall
                                    not affect the  Company's  obligation to pay
                                    Additional   Interest  as   contemplated  in
                                    Section 3.

                           (l)      Prior  to the  effective  date of the  first
                                    Regis  tration  Statement  relating  to  the
                                    Registrable  Securities,   (i)  provide  the
                                    Trustee  with  certificates  for  the  Regis
                                    trable  Securities  in a form  eligible  for
                                    deposit with The  Depository  Trust  Company
                                    and  (ii)  provide  a CUSIP  number  for the
                                    Registrable Securities.

                           (m)      In connection with any underwritten offering
                                    of  Registrable  Securities  pursuant  to

                                      -21-
<PAGE>


                                    a   Shelf   Registration,   enter   into  an
                                    underwriting  agreement  as is  customary in
                                    underwritten offerings of securities similar
                                    to the  Registrable  Securities and take all
                                    such  other   actions   as  are   reasonably
                                    requested  by the  managing  underwriter  or
                                    underwriters;   in  order  to   expedite  or
                                    facilitate   the    registration    or   the
                                    disposition of such  Registrable  Securities
                                    and,  in  such  connection,  (i)  make  such
                                    representations   and   warranties  to,  and
                                    covenants   with,  the   underwriters   with
                                    respect to the  business  of the Company and
                                    its  subsidiaries  (including  any  acquired
                                    business,    properties   or   entity,    if
                                    applicable) and the Registration  Statement,
                                    Prospectus    and    documents,    if   any,
                                    incorporated or deemed to be incorporated by
                                    reference  therein,  in  each  case,  as are
                                    customarily  made by issuers to underwriters
                                    in  underwritten   offerings  of  securities
                                    similar to the  Registrable  Securities  and
                                    confirm  the  same in  writing  if and  when
                                    requested;  (ii) obtain the written  opinion
                                    of  counsel  to  the   Company  and  written
                                    updates thereof in form, scope and substance
                                    reasonably   satisfactory  to  the  managing
                                    underwriter  or  underwriters,  addressed to
                                    the   underwriters   covering   the  matters
                                    customarily covered in opinions requested in
                                    underwritten offerings of securities similar
                                    to the Registrable Securities and such other
                                    matters as may be  reasonably  requested  by
                                    the managing

                                      -22-
<PAGE>

                                    underwriter  or  underwriters;  (iii) obtain
                                    "cold comfort"  letters and updates  thereof
                                    in  form,  scope  and  substance  reasonably
                                    satisfactory to the managing  underwriter or
                                    underwriters from the independent  certified
                                    public  accountants  of the Company (and, if
                                    necessary,  any other independent  certified
                                    public  accountants of any subsidiary of the
                                    Company or of any  business  acquired by the
                                    Company for which  financial  statements and
                                    financial  data are, or are  required to be,
                                    included or incorporated by reference in the
                                    Registration  Statement),  addressed to each
                                    of the  underwriters,  such letters to be in
                                    customary  form and covering  matters of the
                                    type  customarily  covered in "cold comfort"
                                    letters  in con  nection  with  underwritten
                                    offerings  of  securities   similar  to  the
                                    Registrable   Securities   and  such   other
                                    matters  as  reasonably   requested  by  the
                                    managing  underwriter or  underwriters;  and
                                    (iv) if an underwriting agreement is entered
                                    into, the same shall contain indemnification
                                    provisions  and procedures no less favorable
                                    than those set forth in Section 6 hereof (or
                                    such   other   provisions   and   procedures
                                    acceptable  to  Holders  of  a  majority  in
                                    Amount of Registrable  Securities covered by
                                    such Registration Statement and the managing
                                    underwriter or  underwriters or agents) with
                                    respect  to all  parties  to be  indemnified
                                    pursuant to said Section. The above shall be
                                    done

                                      -23-
<PAGE>


                                    at  each  closing  under  such  underwriting
                                    agreement,  or as and to the extent required
                                    thereunder.

                           (n)      Make available for inspection by any selling
                                    Holder of such Registrable  Securities being
                                    sold, any underwriter  participating  in any
                                    such disposition of Registrable  Securities,
                                    if any,  and  any  attorney,  accountant  or
                                    other  agent  retained  by any such  selling
                                    Holder,  or underwriter  (collectively,  the
                                    "Inspectors"), at the offices where normally
                                    kept,  during  reasonable  business hours at
                                    such  time or times  as  shall  be  mutually
                                    convenient   for   the   Company   and   the
                                    Inspectors  as a group,  all  financial  and
                                    other records, pertinent corporate documents
                                    and  instruments  of  the  Company  and  its
                                    subsidiaries  (collectively,  the "Records")
                                    as shall be  reasonably  necessary to enable
                                    them  to   exercise   any   applicable   due
                                    diligence  responsibilities,  and  cause the
                                    officers,  directors  and  employees  of the
                                    Company and its  subsidiaries  to supply all
                                    information reasonably requested by any such
                                    Inspector    in    connection    with   such
                                    Registration  Statement.  Records  that  the
                                    Company  determines,  in good  faith,  to be
                                    confidential   and  any   Records   that  it
                                    notifies  the  Inspectors  are  confidential
                                    shall  not be  disclosed  by  any  Inspector
                                    unless (i) the disclosure of such Records is
                                    necessary to avoid or correct a

                                      -24-
<PAGE>

                                    material  misstatement or material  omission
                                    in such  Registration  Statement,  (ii)  the
                                    release of such Records is ordered  pursuant
                                    to a subpoena or other order from a court of
                                    competent jurisdiction,  (iii) disclosure of
                                    such  information  is,  in  the  opinion  of
                                    counsel  for  any  Inspector,  necessary  or
                                    advisable  in  connection  with any  action,
                                    claim,   suit   or   proceeding,   directly,
                                    involving  or  potentially   involving  such
                                    Inspector  and arising  out of,  based upon,
                                    relating to, or involving  this Agreement or
                                    any  transactions   contemplated  hereby  or
                                    arising hereunder or (iv) the information in
                                    such   Records   has  been  made   generally
                                    available  to the public  other than through
                                    the  acts of such  Inspector.  Each  selling
                                    Holder of such  Registrable  Securities will
                                    be  required   to  agree  that   information
                                    obtained   by  it  as  a   result   of  such
                                    inspections shall be deemed confidential and
                                    shall not be used by it as the basis for any
                                    market transactions in the securities of the
                                    Company unless and until such information is
                                    generally  available  to  the  public.  Each
                                    selling    Holder   of   such    Registrable
                                    Securities will be required to further agree
                                    that it will,  upon learning that disclosure
                                    of such  Records  is  sought  in a court  of
                                    competent  jurisdiction,  give notice to the
                                    Company and allow the  Company to  undertake
                                    appropriate  action to prevent disclosure of
                                    the Records deemed

                                      -25-
<PAGE>

                                    confidential at the Company's sole expense.

                           (o)      Provide (A) the  Holders of the  Registrable
                                    Securities    to   be   included   in   such
                                    registration statement and not more than one
                                    counsel   for  all  the   Holders   of  such
                                    Registrable Securities, (B) the underwriters
                                    (which   term,    for   purposes   of   this
                                    Registration Rights Agreement, shall include
                                    a person deemed to be an underwriter  within
                                    the   meaning  of   Section   2(11)  of  the
                                    Securities  Act), if any,  thereof,  (C) the
                                    sales or placement  agent, if any,  thereof,
                                    and (D) one counsel for such underwriters or
                                    agents,     reasonable     opportunity    to
                                    participate  in  the   preparation  of  such
                                    registration   statement,   each  prospectus
                                    included  therein or filed with the SEC, and
                                    each amendment or supplement thereto.

                           (p)      Comply   with  all   applicable   rules  and
                                    regulations  of the SEC and  make  generally
                                    available  to  its  securityholders  earning
                                    statements   satisfying  the  provisions  of
                                    Section 11(a) of the Securities Act and Rule
                                    158   thereunder   (or  any   similar   rule
                                    promulgated  under  the  Securities  Act) no
                                    later  than  45  days  after  the end of any
                                    12-month period (or 90 days after the end of
                                    any  12-month  period  if such  period  is a
                                    fiscal  year) (i)  commencing  at the end of
                                    any  fiscal  quarter  in  which  Registrable
                                    Securities  are  sold to  underwriters  in a
                                    firm commitment or best efforts

                                      -26-
<PAGE>

                                    underwritten  offering  and (ii) if not sold
                                    to   underwriters   in  such  an   offering,
                                    commencing  on the  first  day of the  first
                                    fiscal  quarter  of the  Company  after  the
                                    effective date of a Registration  Statement,
                                    which  statements  shall cover said 12-month
                                    periods.

                           (q)      Cooperate  with each  seller of  Registrable
                                    Securities   covered  by  any   Registration
                                    Statement  and  each  underwriter,  if  any,
                                    participating  in the  disposition  of  such
                                    Registrable  Securities and their respective
                                    counsel  in  connection   with  any  filings
                                    required  to  be  made  with  the   National
                                    Association of Securities Dealers, Inc. (the
                                    "NASD"),  including  if the  Rules  of  Fair
                                    Practice  and the  ByLaws of the NASD or any
                                    successor  thereto,  as amended from time to
                                    time  (including   Schedule  E  thereto)  so
                                    require,  engaging a "qualified  independent
                                    underwriter" ("QIU") as contemplated therein
                                    and making Records  available to such QIU as
                                    though it were a  participating  underwriter
                                    for  the   purposes  of  Section   4(n)  and
                                    otherwise  applying the  provisions  of this
                                    Agreement    to    such    QIU    (including
                                    indemnification)   as   though   it  were  a
                                    participating underwriter.

                           (r)      Cause the  Indenture to be  qualified  under
                                    the TIA not later than the effective date of
                                    the first Registration Statement relating to
                                    the   Registrable    Securities;    and   in
                                    connection

                                      -27-
<PAGE>

                                    therewith,  cooperate  with the  Trustee and
                                    the Holders of the Registrable Securities to
                                    effect such changes to the  Indenture as may
                                    be  required  for  the  Indenture  to  be so
                                    qualified  in  accordance  with the terms of
                                    the TIA; and execute, and use its reasonable
                                    best   efforts  to  cause  the   Trustee  to
                                    execute, all documents as may be required to
                                    effect such changes, and all other forms and
                                    documents  required to be filed with the SEC
                                    to enable the  Indenture  to be so qualified
                                    in a timely manner.

                           (s)      Use its reasonable best efforts to cause the
                                    Registrable    Securities   covered   by   a
                                    Registration Statement, to be rated with the
                                    appropriate rating agencies, if so requested
                                    by the  Holders of a  majority  in Amount of
                                    Registrable   Securities   covered  by  such
                                    Registration   Statement,  or  the  managing
                                    underwriter or underwriters, if any.

                           (t)      Use its reasonable  best efforts to take all
                                    other steps necessary or advisable to effect
                                    the    registration   of   the   Registrable
                                    Securities   covered   by   a   Registration
                                    Statement contemplated hereby.

         The Company may require  each seller of  Registrable  Securities  as to
which  any  registration  is being  effected  to  furnish  to the  Company  such
information  regarding  such  seller and the  distribution  of such  Registrable
Securities  as the Company  may,  from time to time,  reasonably  request to the
extent necessary or advisable to comply with the

                                      -28-
<PAGE>

Securities Act. The Company may exclude from such  registration  the Registrable
Securities  of any seller who  unreasonably  fails to furnish  such  information
within a reasonable time after  receiving such request.  Each seller as to which
any Shelf  Registration  is being  effected  agrees to furnish  promptly  to the
Company  all  information  required  to  be  disclosed  in  order  to  make  the
information  previously  furnished to the Company by such seller not  materially
misleading or to omit to state any material  fact required to be stated  therein
or  necessary  to make the  statements  therein not  misleading  in light of the
circumstances under which they were made.

         Each Holder of  Registrable  Securities  agrees by  acquisition of such
Registrable  Securities that, upon actual receipt of any notice from the Company
of the  happening  of any event of the kind  described  in Section  4(c)(ii)(C),
4(c)(iv) or 4(c)(v) hereof, such Holder will forthwith  discontinue  disposition
of such  Registrable  Securities  covered  by  such  Registration  Statement  or
Prospectus  until such  Holder's  receipt of the copies of the  supplemented  or
amended  Prospectus  contemplated by Section 4(k) hereof, or until it is advised
in  writing  (the  "Advice")  by the  Company  that  the  use of the  applicable
Prospectus  may be  resumed,  and  has  received  copies  of any  amendments  or
supplements thereto.

         5.       Registration Expenses

                           (a)      All  fees  and  expenses   incident  to  the
                                    performance  of  or  compliance   with  this
                                    Agreement  by the Company  shall be borne by
                                    the   Company   whether   or  not  a   Shelf
                                    Registration is filed or becomes  effective,
                                    including,   without  limitation,   (i)  all
                                    registration  and  filing  fees  (including,
                                    without limitation, (A) fees with respect to
                                    filings required to be made with the NASD in
                                    connection with an underwritten offering and
                                    (B) fees and expenses


                                      -29-
<PAGE>

                                    of compliance with state  securities or Blue
                                    Sky  laws  (including,  without  limitation,
                                    reasonable fees and disbursements of counsel
                                    in connection  with Blue Sky  qualifications
                                    of   the    Registrable    Securities    and
                                    determination  of  the  eligibility  of  the
                                    Registrable  Securities for investment under
                                    the laws of such  jurisdictions  as provided
                                    in  Section  4(h)  hereof,  in the  case  of
                                    Registrable   Securities),   (ii)   printing
                                    expenses,   including,  without  limitation,
                                    expenses   of  printing   certificates   for
                                    Registrable  Securities  in a form  eligible
                                    for  deposit  with  The   Depository   Trust
                                    Company and of printing  prospectuses if the
                                    printing of prospectuses is requested by the
                                    managing  underwriter  or  underwriters,  if
                                    any,  by the Holders of a majority of shares
                                    of the  Registrable  Securities  included in
                                    any Registration Statement, (iii) messenger,
                                    telephone and delivery  expenses,  (iv) fees
                                    and disbursements of counsel for the Company
                                    and  fees  and   disbursements   of  special
                                    counsel  for  the  sellers  of   Registrable
                                    Securities  (subject  to the  provisions  of
                                    Section   5(b)   hereof),   (v)   fees   and
                                    disbursements  of all independent  certified
                                    public  accountants  referred  to in Section
                                    4(m)(iii)   hereof    (including,    without
                                    limitation,  the  expenses  of  any  special
                                    audit and "cold comfort" letters required by
                                    or  incident  to  such  performance),   (vi)
                                    rating  agency fees,  (vii)

                                      -30-
<PAGE>

                                    Securities Act liability  insurance,  if the
                                    Company desires such insurance,  (viii) fees
                                    and expenses of all other  Persons  retained
                                    by the Company,  (ix)  internal  expenses of
                                    the Company (including,  without limitation,
                                    all  salaries  and  expenses of officers and
                                    employees of the Company performing legal or
                                    accounting  duties),  (x) the expense of any
                                    annual  audit,  (xi) the  fees and  expenses
                                    incurred in  connection  with the listing of
                                    the  securities  to  be  registered  on  any
                                    securities  exchange,  if  applicable,   and
                                    (xii) the  expenses  relating  to  printing,
                                    word   processing   and   distributing   all
                                    Registration    Statements,     underwriting
                                    agreements,   securities  sales  agreements,
                                    indentures and any other documents necessary
                                    in order to comply with this Agreement.

                           (b)      The Company  shall  reimburse the Holders of
                                    the Registrable  Securities being registered
                                    in a Shelf Regis tration for the  reasonable
                                    fees and  disbursements of not more than one
                                    counsel (in  addition to  appropriate  local
                                    counsel) chosen by the Holders of a majority
                                    in Amount of the  Registrable  Securities to
                                    be included in such  Registration  Statement
                                    and other reasonable  out-of-pocket expenses
                                    of such  Holders of  Registrable  Securities
                                    incurred in connection with the registration
                                    and  sale  of  the  Registrable   Securities
                                    pursuant to any Registration Statement.

                                      -31-
<PAGE>

         6.       Indemnification

                           (a)      The Company will indemnify and hold harmless
                                    each Holder of Registrable Securities,  each
                                    Person that  participates  as an underwriter
                                    or   sales   agent   in  any  sale  of  such
                                    Registrable      Securities      (each     a
                                    "Participant")  against any losses,  claims,
                                    damages or liabilities, joint or several, to
                                    which such  Participant  may become subject,
                                    under the Securities Act or the Exchange Act
                                    or   otherwise,   insofar  as  such  losses,
                                    claims,  damages or liabilities  (or actions
                                    in  respect  thereof)  arise  out  of or are
                                    based upon any untrue  statement  or alleged
                                    untrue   statement  of  any  material   fact
                                    contained in any  Registration  Statement or
                                    Prospectus,  or any  amendment or supplement
                                    thereto   or   any    related    preliminary
                                    prospectus or arise out of or are based upon
                                    the  omission  or alleged  omission to state
                                    therein a material  fact  necessary in order
                                    to make the statements therein, in the light
                                    of the  circumstances  under which they were
                                    made,  not  misleading,  and will  reimburse
                                    each   Purchaser  for  any  legal  or  other
                                    expenses   reasonably   incurred   by   such
                                    Purchaser in connection  with  investigating
                                    or defending any such loss,  claim,  damage,
                                    liability  or  action as such  expenses  are
                                    incurred;   provided,   however,   that  the
                                    Company  will not be liable in any such case
                                    to the extent that any such loss, claim,

                                      -32-
<PAGE>

                                    damage  or  liability  arises  out  of or is
                                    based  upon an untrue  statement  or alleged
                                    untrue  statement  in or omission or alleged
                                    omission  from  any  of  such  documents  in
                                    reliance upon and in conformity with written
                                    information  furnished to the Company by any
                                    Participant  specifically  for use  therein;
                                    provided, further, that the Company will not
                                    be  liable  if  such  untrue   statement  or
                                    omission  or  alleged  untrue  statement  or
                                    omission  was   contained  or  made  in  any
                                    preliminary  prospectus and corrected in the
                                    Prospectus  or any  amendment or  supplement
                                    thereto and the Prospectus  does not contain
                                    any other  untrue  statement  or omission or
                                    alleged  untrue  statement  or omission of a
                                    material fact that was the subject matter of
                                    the  related  proceeding  and any such loss,
                                    liability, claim, damage or expense suffered
                                    or  incurred  by the  Participants  resulted
                                    from any action, claim or suit by any Person
                                    who purchased Registrable Securities that is
                                    the subject  thereof  from such  Participant
                                    and  it  is   established   in  the  related
                                    proceeding that such  Participant  failed to
                                    deliver or provide a copy of the  Prospectus
                                    (as amended or  supplemented) to such Person
                                    with or  prior  to the  confirmation  of the
                                    sale of such Registrable  Securities sold to
                                    such Person if required by  applicable  law,
                                    unless such  failure to deliver or provide a
                                    copy  of  the   Prospectus  (as  amended  or
                                    supplemented) was a result of

                                      -33-
<PAGE>

                                    noncompliance  by the Company with Section 4
                                    of this Agreement.

                           (b)      The Company may  require,  as a condition to
                                    including  Registrable   Securities  in  any
                                    Registration  Statement,  that  the  related
                                    Participants agree severally and not jointly
                                    to indemnify  and hold  harmless the Company
                                    against  any  losses,   claims,  damages  or
                                    liabilities  to which the Company may become
                                    subject,  under  the  Securities  Act or the
                                    Exchange Act or  otherwise,  insofar as such
                                    losses,  claims,  damages or liabilities (or
                                    actions in respect  thereof) arise out of or
                                    are  based  upon  any  untrue  statement  or
                                    alleged  untrue  statement  of any  material
                                    fact contained in any Registration Statement
                                    or   Prospectus,   or   any   amendment   or
                                    supplement    thereto,    or   any   related
                                    prospectus,  or  arise  out of or are  based
                                    upon the omission or the alleged omission to
                                    state therein a material  fact  necessary in
                                    order to make the statements therein, in the
                                    light of the circumstances  under which they
                                    were made, not  misleading,  in each case to
                                    the  extent,  but only to the  extent,  that
                                    such  untrue  statement  or  alleged  untrue
                                    statement  or omission  or alleged  omission
                                    was made in reliance  upon and in conformity
                                    with  written  information  furnished to the
                                    Company by such Participant specifically for
                                    use therein, and will reimburse any legal or
                                    other expenses reasonably incurred by the

                                      -34-
<PAGE>

                                    Company in connection with  investigating or
                                    defending  any  such  loss,  claim,  damage,
                                    liability  or  action as such  expenses  are
                                    incurred.  The liability of any  Participant
                                    under  this  subsection  shall  in no  event
                                    exceed  the net  proceeds  received  by such
                                    Participant   from   sales  of   Registrable
                                    Securities giving rise to such obligations.

                           (c)      Promptly  after  receipt  by an  indemnified
                                    party  under  this  Section of notice of the
                                    commencement of any action, such indemnified
                                    party will, if a claim in respect thereof is
                                    to be made  against the  indemnifying  party
                                    under  subsection  (a) or (b) above,  notify
                                    the  indemnifying  party of the commencement
                                    thereof;  but the  omission so to notify the
                                    indemnifying  party will not relieve it from
                                    any  liability  which  it  may  have  to any
                                    indemnified  party  other  wise  than  under
                                    subsection  (a) or (b)  above.  In case  any
                                    such   action   is   brought   against   any
                                    indemnified   party  and  it  notifies   the
                                    indemnifying   party  of  the   commencement
                                    thereof,  the  indemnifying  party  will  be
                                    entitled to participate  therein and, to the
                                    extent  that it may wish,  jointly  with any
                                    other indemnifying party similarly notified,
                                    to assume the defense thereof,  with counsel
                                    satisfactory to such indemnified  party (who
                                    shall not,  except  with the  consent of the
                                    indemnified   party,   be   counsel  to  the
                                    indemnifying party), and after

                                      -35-
<PAGE>


                                    notice from the  indemnifying  party to such
                                    indemnified  party  of  its  election  so to
                                    assume the defense thereof, the indemnifying
                                    party will not be liable to such indemnified
                                    party  under this  Section  for any legal or
                                    other expenses subsequently incurred by such
                                    indemnified  party  in  connection  with the
                                    defense thereof other than reasonable  costs
                                    of  investigation.   No  indemnifying  party
                                    shall,  without the prior written consent of
                                    the indemnified party, effect any settlement
                                    of  any  pending  or  threatened  action  in
                                    respect of which any indemnified party is or
                                    could have been a party and indemnity  could
                                    have   been   sought   hereunder   by   such
                                    indemnified  party  unless  such  settlement
                                    includes  an  unconditional  release of such
                                    indemnified  party from all liability on any
                                    claims that are the  subject  matter of such
                                    action.

                           (d)      If the indemnification  provided for in this
                                    Section is  unavailable or  insufficient  to
                                    hold  harmless  an  indemnified  party under
                                    subsection  (a)  or  (b)  above,  then  each
                                    indemnifying  party shall  contribute to the
                                    amount  paid or payable by such  indemnified
                                    party as a  result  of the  losses,  claims,
                                    damages  or   liabilities   referred  to  in
                                    subsection  (a) or  (b)  above  (i) in  such
                                    proportion as is  appropriate to reflect the
                                    relative benefits received by the Company on
                                    the one hand and the Participants on the

                                      -36-
<PAGE>

                                    other from the  offering of the  Registrable
                                    Securities   or  (ii)   if  the   allocation
                                    provided   by   clause   (i)  above  is  not
                                    permitted   by   applicable   law,  in  such
                                    proportion as is  appropriate to reflect not
                                    only the  relative  benefits  referred to in
                                    clause (i) above but also the relative fault
                                    of the  Company  on the  one  hand  and  the
                                    Participants on the other in connection with
                                    the  statements or omissions  which resulted
                                    in   such   losses,   claims,   damages   or
                                    liabilities  as well as any  other  relevant
                                    equitable   considerations.   The   relative
                                    benefits  received by the Company on the one
                                    hand and any  Participant on the other shall
                                    be  deemed to be in the same  proportion  as
                                    the  total  net  proceeds  from the  initial
                                    offering  of  the   Registrable   Securities
                                    (before deducting  expenses) received by the
                                    Company  bear  to  the  total  net  proceeds
                                    received by such  Participant  from sales of
                                    Registrable  Securities  giving rise to such
                                    obligations.  The  relative  fault  shall be
                                    determined  by  reference  to,  among  other
                                    things, whether the untrue or alleged untrue
                                    statement of a material fact or the omission
                                    or alleged omission to state a material fact
                                    relates  to  information   supplied  by  the
                                    Company or such Participant and the parties'
                                    relative   intent,   knowledge,   access  to
                                    information  and  opportunity  to correct or
                                    prevent  such untrue  statement or omission.
                                    The amount paid by an indemnified

                                      -37-
<PAGE>

                                    party as a  result  of the  losses,  claims,
                                    damages or  liabilities  referred  to in the
                                    first sentence of this  subsection (d) shall
                                    be  deemed  to  include  any  legal or other
                                    expenses   reasonably   incurred   by   such
                                    indemnified   party   in   connection   with
                                    investigating  or  defending  any  action or
                                    claim   which   is  the   subject   of  this
                                    subsection    (d).    Notwithstanding    the
                                    provisions  of  this   subsection   (d),  no
                                    Participant  shall be required to contribute
                                    any  amount in excess of the amount by which
                                    the   net   proceeds    received   by   such
                                    Participant   from   sales  of   Registrable
                                    Securities exceeds the amount of any damages
                                    which such  Participant  has otherwise  been
                                    required  to pay by reason of such untrue or
                                    alleged  untrue  statement  or  omission  or
                                    alleged   omission.   No  person  guilty  of
                                    fraudulent   misrepresentation  (within  the
                                    meaning of  Section  11(f) of the Act) shall
                                    be entitled to contribution  from any person
                                    who  was  not  guilty  of  such   fraudulent
                                    misrepresentation.     The     Participants'
                                    obligations   in  this   subsection  (d)  to
                                    contribute  are  several  in  proportion  to
                                    their  respective   Amounts  of  Registrable
                                    Securities   registered   pursuant  to  this
                                    Agreement, and not joint.


                                      -38-

<PAGE>

                           (e)      The  obligations  of the Company  under this
                                    Section   shall  be  in   addition   to  any
                                    liability  which the Company  may  otherwise
                                    have and shall  extend,  upon the same terms
                                    and  conditions,  to each officer,  director
                                    and partner of each  Participant and to each
                                    Person, if any, who controls any Participant
                                    within the meaning of the  Securities Act or
                                    the Exchange Act; and the obligations of the
                                    Participant  under this Section  shall be in
                                    addition   to  any   liability   which   the
                                    respective  Participants  otherwise have and
                                    shall  extend,   upon  the  same  terms  and
                                    conditions,  to each officer and director of
                                    the Company and to each Person,  if any, who
                                    controls  the Company  within the meaning of
                                    the Securities Act or the Exchange Act.

         7. Rules 144 and 144A.

         The  Company  covenants  that it will file the  reports  required to be
filed by it under  the  Securities  Act and the  Exchange  Act and the rules and
regulations  adopted by the SEC thereunder in a timely manner in accordance with
the  requirements  of the Securities Act and the Exchange Act and such rules and
regulations  and,  if at any time  the  Company  is not  required  to file  such
reports, it will, upon the request of any Holder of Registrable Securities, make
publicly  available  annual  reports and such  information,  documents and other
reports of the type  specified in Sections 13 and 15(d) of the Exchange Act. The
Company  further  covenants  for so long as any  Registrable  Securities  remain
outstanding,  to make available to any Holder or beneficial owner of Registrable
Securities in connection with any sale thereof and any prospective  purchaser of
such  Registrable   Securities  from  such  Holder  or  beneficial   owner,  the
information  required by Rule  144A(d)(4)  under the

                                      -39-
<PAGE>

Securities  Act in  order  to  permit  resales  of such  Registrable  Securities
pursuant to Rule 144A.

         8.       Underwritten Registrations.

         If any of the Registrable  Securities covered by any Shelf Registration
is to be sold in an underwritten  offer ing, the investment banker or investment
bankers and manager or managers  that will manage the offering  will be selected
by the Holders of a majority in Amount of such Registrable  Securities  included
in such offering and reasonably acceptable to the Company.

         No Holder of Registrable Securities may participate in any underwritten
registration  hereunder  unless  such  Holder (a)  agrees to sell such  Holder's
Registrable  Securities on the basis provided in any  underwriting  arrangements
approved by the Persons entitled  hereunder to approve such arrangements and (b)
completes  and executes  all  questionnaires,  powers of attorney,  indemnities,
underwriting  agreements  and other  documents  required under the terms of such
underwriting arrangements.

         9.       Representations and Warranties.

         The Company represents and warrants to, and agrees with, each Purchaser
and each of the Holders from time to time of Registrable Securities that:

                           (a)      Each   registration    statement    covering
                                    Registrable  Securities and each  prospectus
                                    (including   any   preliminary   or  summary
                                    prospectus)  contained  therein or furnished
                                    pursuant to this  Agreement  and any further
                                    amendments  or   supplements   to  any  such
                                    registration  statement or prospectus,  when
                                    it  becomes  effective  or is filed with the
                                    SEC, as the case may be, and, in the case of
                                    an  underwritten   offering  of  Registrable
                                    Securities, at the time

                                      -40-
<PAGE>

                                    of  the  closing   under  the   underwriting
                                    agreement relating thereto,  will conform in
                                    all material respects to the requirements of
                                    the Securities Act and the TIA and the rules
                                    and  regulations  of the SEC  and  any  such
                                    registration  statement  and  any  amendment
                                    thereto   will  not   include   any   untrue
                                    statement  of a  material  fact  or  omit to
                                    state  any  material  fact  required  to  be
                                    stated  therein  or  necessary  to make  the
                                    statements  therein not  misleading  and any
                                    such   prospectus   or  any   amendment   or
                                    supplement  thereto  will  not  include  any
                                    untrue  statement of a material fact or omit
                                    to  state a  material  fact  required  to be
                                    stated  therein  or  necessary  to make  the
                                    statements  therein not  misleading in light
                                    of the circumstances  then existing;  and at
                                    all times  subsequent to the effective  time
                                    of any such  registration  statement  when a
                                    prospectus would be required to be delivered
                                    under the  Securities  Act,  other than from
                                    (i) such time as a notice  has been given to
                                    Holders of Registrable  Securities  pursuant
                                    to the last  paragraph  of  Section  4(t) or
                                    pursuant to Section  4(k) hereof  until (ii)
                                    such  time  as  the  Company   furnishes  an
                                    amended or supplemented  prospectus pursuant
                                    to Section 4(k) hereof or otherwise gives an
                                    Advice,  each such  registration  statement,
                                    and each  prospectus  (including any summary
                                    prospectus)  con tained therein or furnished
                                    pursuant  to Section  4(k) or  Section  4(g)
                                    hereof, as then

                                      -41-
<PAGE>

                                    amended or supplemented, will conform in all
                                    material respects to the requirements of the
                                    Securities Act and the TIA and the rules and
                                    regulations  of the  Commission and will not
                                    include any untrue statement of any material
                                    fact  or  omit  to  state  a  material  fact
                                    required to be stated  therein or  necessary
                                    to   make   the   statements   therein   not
                                    misleading in the light of the circumstances
                                    then existing;  provided, however, that this
                                    representation  and warranty  does not apply
                                    to  any   statements  or  omissions  from  a
                                    registration    statement   or    prospectus
                                    (including   any   preliminary   or  summary
                                    prospectus)  based upon written  information
                                    furnished to the Company by any underwriter,
                                    sales agent or Holder  specifically  for use
                                    therein.

                           (b)      Any documents  incorporated  by reference in
                                    any  prospectus  referred to in Section 4(a)
                                    hereof, when they become or became effective
                                    or are or were  filed  with the SEC,  as the
                                    case may be, will  conform or  conformed  in
                                    all material respects to the requirements of
                                    the  Securities  Act or the Exchange Act, as
                                    applicable,  and none of such documents will
                                    include or included any untrue  statement of
                                    a  material  fact or will omit or omitted to
                                    state  any  material  fact  required  to  be
                                    stated  therein  or  necessary  to make  the
                                    statements therein not misleading; provided,
                                    however,   that  this

                                      -42-
<PAGE>

                                    representation  and warranty  does not apply
                                    to  any   statements  or  omissions  from  a
                                    registration  statement  or  the  prospectus
                                    (including   any   preliminary   or  summary
                                    prospectus)  based upon written  information
                                    furnished to the Company by any underwriter,
                                    sales agent or Holder  specifically  for use
                                    therein.

                           (c)      The  issuance  and  sale of the  Registrable
                                    Securities  did not and  will  not,  and the
                                    execution,  delivery and performance of this
                                    Agreement  and  the   consummation   of  the
                                    transactions  herein  contemplated will not,
                                    result  in a breach or  violation  of any of
                                    the terms and provisions of, or constitute a
                                    default    under,    any   statute,    rule,
                                    regulation,   order   or   policy   of   any
                                    governmental  agency  or body or any  court,
                                    domestic  or  foreign,  having  jurisdiction
                                    over the  Company or any  subsidiary  of the
                                    Company  or any  of  their  properties,  the
                                    Credit   Agreements   (as   defined  in  the
                                    Purchase  Agreement) or any other  agreement
                                    or  instrument  to which the  Company or any
                                    such  subsidiary  is a party or by which the
                                    Company or any such  subsidiary  is bound or
                                    to which the Company or any such  subsidiary
                                    has agreed to become bound,  or to which any
                                    of the properties of the Company or any such
                                    subsidiary  is  subject,  or the  charter or
                                    by-laws (or other  constituent  document) of
                                    the Company or any such subsidiary.

                                      -43-
<PAGE>

         10.      Miscellaneous

                           (a)      No Inconsistent Agreements.  The Company has
                                    not, as of the date hereof,  and the Company
                                    shall not, after the date of this Agreement,
                                    enter into any agreement with respect to any
                                    of its securities that is inconsistent  with
                                    the  rights   granted  to  the   Holders  of
                                    Registrable  Securities in this Agreement or
                                    otherwise   conflicts  with  the  provisions
                                    hereof. The Company has not entered and will
                                    not enter into any agreement with respect to
                                    any of its securities that will grant to any
                                    Person  piggyback  registration  rights with
                                    respect to a Registration Statement,  except
                                    to  the  extent  any   existing   right  has
                                    heretofore been waived.

                           (b)      Adjustments       Affecting      Registrable
                                    Securities.  The Company shall not, directly
                                    or indirectly,  take any action with respect
                                    to the  Registrable  Securities  as a  class
                                    that would  adversely  affect the ability of
                                    the  Holders of  Registrable  Securities  to
                                    include  such  Registrable  Securities  in a
                                    registration  undertaken  pursuant  to  this
                                    Agreement.

                                      -44-
<PAGE>

                           (c)      Amendments  and Waivers.  The  provisions of
                                    this Agreement may not be amended,  modified
                                    or supplemented,  and waivers or consents to
                                    departures  from the  provisions  hereof may
                                    not be given,  otherwise than with the prior
                                    written  consent  of  the  Company  and  the
                                    Holders  of  not  less  than a  majority  in
                                    Amount of the then  outstanding  Registrable
                                    Securities;  provided, however, that Section
                                    6 and this Section 10(c) may not be amended,
                                    modified or  supplemented  without the prior
                                    written  consent  of the  Company  and  each
                                    Holder   (including,   in  the  case  of  an
                                    amendment,  modification  or  supplement  of
                                    Section  6, any  person  who was a Holder of
                                    Registrable Securities, disposed of pursuant
                                    to     any     Registration      Statement).
                                    Notwithstanding  the foregoing,  a waiver or
                                    consent to depart from the provisions hereof
                                    with   respect  to  a  matter  that  relates
                                    exclusively  to the  rights  of  Holders  of
                                    Registrable  Securities whose securities are
                                    being  sold   pursuant  to  a   Registration
                                    Statement  and  that  does not  directly  or
                                    indirectly   affect,    impair,   limit   or
                                    compromise  the  rights of other  Holders of
                                    Registrable   Securities  may  be  given  by
                                    Holders of at least a

                                      -45-
<PAGE>


                                    majority   in  Amount  of  the   Registrable
                                    Securities   being  sold  by  such   Holders
                                    pursuant  to  such  Registration  Statement;
                                    provided,  however,  that the  provisions of
                                    this  sentence may not be amended,  modified
                                    or  supplemented  except in accordance  with
                                    the provisions of the immediately  preceding
                                    sentence.

                           (d)      Notices.     All     notices    and    other
                                    communications  provided  for  or  permitted
                                    hereunder   shall  be  made  in  writing  by
                                    hand-delivery,  registered first-class mail,
                                    next-day air courier or facsimile:

         (1) if to a Holder of the Registrable  Securities,  at the most current
address of such Holder on the Security  Register (as defined in the  Indenture),
in the case of Convertible  Notes,  and the stock ledger of the Company,  in the
case of  Class  A  Common  Stock,  with a copy in  like  manner  to the  Initial
Purchasers as follows:

                                      -46-
<PAGE>


               CREDIT SUISSE FIRST BOSTON CORPORATION
               DEUTSCHE BANK SECURITIES INC.
               LEHMAN BROTHERS INC.
               MORGAN STANLEY & CO. INCORPORATED
               BANC OF AMERICA SECURITIES LLC
               BEAR, STEARNS & CO. INC.
               GOLDMAN, SACHS & CO.
               MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED
               SALOMON SMITH BARNEY INC.
               c/o Credit Suisse First Boston Corporation
               Eleven Madison Avenue
               New York, New York  10010
               Facsimile No:  (212) 325-8278
               Attention:  Investment Banking Department
                           Transactions Advisory Group


         with a copy to:

               Sullivan & Cromwell
               125 Broad Street
               New York, New York  10004
               Facsimile No.:  (212) 558-3588
               Attention:  John T. Bostelman, Esq.

         (2) if to the Initial Purchasers, at the addresses specified in Section
10(d)(1);

         (3)      if to the Company, at the addresses as follows:

               American Tower Corporation
               116 Huntington Avenue
               Boston, Massachusetts  02116
               Facsimile No.:  (617) 375-7575
               Attention:  Chief Financial Officer

with copies to:

               Sullivan & Worcester LLP
               One Post Office Square
               Boston, Massachusetts 02109
               Facsimile No.:  (617) 338-2880
               Attention:  Norman Bikales, Esq.

                                      -47-
<PAGE>

         All such notices and  communications  shall be deemed to have been duly
given: when delivered by hand, if personally delivered; five business days after
being deposited in the mail, postage prepaid,  if mailed; one business day after
being  timely  delivered  to  a  next-day  air  courier;  and  when  receipt  is
acknowledged by the addressee, if sent by facsimile.

                           (e)      Successors and Assigns. This Agreement shall
                                    inure to the benefit of and be binding  upon
                                    the  successors  and  assigns of each of the
                                    parties   hereto,   including  the  Holders;
                                    provided, however, that this Agreement shall
                                    not inure to the  benefit  of or be  binding
                                    upon  a  successor  or  assign  of a  Holder
                                    unless  and   except  to  the  extent   such
                                    successor   or  assign   holds   Registrable
                                    Securities.

                           (f)      Counterparts. This Agreement may be executed
                                    in any  number  of  counterparts  and by the
                                    parties  hereto  in  separate  counterparts,
                                    each of  which  when so  executed  shall  be
                                    deemed  to be an  original  and all of which
                                    taken together shall  constitute one and the
                                    same agreement.

                           (g)      Headings. The headings in this Agreement are
                                    for  convenience of reference only and shall
                                    not limit or  otherwise  affect the  meaning
                                    hereof.

                           (h)      Governing  Law.  THIS  AGREEMENT   SHALL  BE
                                    GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH
                                    THE  LAWS  OF  THE  STATE  OF NEW  YORK,  AS
                                    APPLIED TO

                                      -48-
<PAGE>

                                    CONTRACTS  MADE AND PERFORMED  WHOLLY WITHIN
                                    THE  STATE OF NEW  YORK,  WITHOUT  REGARD TO
                                    PRINCIPLES  OF CONFLICTS OF LAW. EACH OF THE
                                    PARTIES  HERETO  AGREES  TO  SUBMIT  TO  THE
                                    JURISDICTION  OF THE  COURTS OF THE STATE OF
                                    NEW YORK IN ANY ACTION OR PROCEEDING ARISING
                                    OUT OF OR RELATING TO THIS AGREEMENT.

                           (i)      Severability.   If  any   term,   provision,
                                    covenant or restriction of this Agreement is
                                    held by a court of competent jurisdiction to
                                    be invalid,  illegal, void or unenforceable,
                                    the  remainder  of  the  terms,  provisions,
                                    covenants and  restrictions set forth herein
                                    shall  remain in full  force and  effect and
                                    shall  in no way be  affected,  impaired  or
                                    invalidated,  and the parties  hereto  shall
                                    use their best efforts to find and employ an
                                    alternative  means  to  achieve  the same or
                                    substantially   the  same   result  as  that
                                    contemplated   by  such   term,   provision,
                                    covenant  or   restriction.   It  is  hereby
                                    stipulated  and declared to be the intention
                                    of the parties that they would have executed
                                    the remaining terms,  provisions,  covenants
                                    and  restrictions  without  including any of
                                    such that may be hereafter declared invalid,
                                    illegal, void or unenforceable.

                           (j)      Securities   Held  by  the  Company  or  Its
                                    Affiliates. Whenever the consent or approval
                                    of  Holders  of a  specified  percentage  in
                                    Amount of Registrable Securities is required

                                      -49-
<PAGE>

                                    hereunder,  Registrable  Securities  held by
                                    the Company or its  affiliates (as such term
                                    is defined in Rule 405 under the  Securities
                                    Act)  shall not be  counted  in  determining
                                    whether  such  consent or approval was given
                                    by the Holders of such required percentage.

                           (k)      Third   Party   Beneficiaries.   Holders  of
                                    Registrable  Securities  are intended  third
                                    party  beneficiaries  of this  Agreement and
                                    this  Agreement  may  be  enforced  by  such
                                    Persons.

                           (l)      Entire Agreement.  This Agreement,  together
                                    with   the   Purchase   Agreement   and  the
                                    Indenture,  is  intended by the parties as a
                                    final  and   exclusive   statement   of  the
                                    agreement and  understanding  of the parties
                                    hereto  in  respect  of the  subject  matter
                                    contained herein and therein and any and all
                                    prior    oral   or    written    agreements,
                                    representations,  or warranties,  contracts,
                                    understandings,              correspondence,
                                    conversations   and  memoranda  between  the
                                    Initial  Purchasers  on the one hand and the
                                    Company  on the  other,  or between or among
                                    any   agents,   representatives,    parents,
                                    subsidiaries,  affiliates,  predecessors  in
                                    interest  or  successors  in  interest  with
                                    respect  to the  subject  matter  hereof and
                                    thereof  are  merged   herein  and  replaced
                                    hereby.


                                      -50-
<PAGE>


         IN WITNESS WHEREOF,  the parties have executed this Agreement as of the
date first written above.


                                      AMERICAN TOWER CORPORATION



                                      By:         /s/ Joseph L. Winn
                                               Name:  Joseph L. Winn
                                               Title: Chief Financial Officer


                                      CREDIT SUISSE FIRST BOSTON
                                        CORPORATION
                                      DEUTSCHE BANK SECURITIES INC.
                                      LEHMAN BROTHERS INC.
                                      MORGAN STANLEY & CO. INCORPORATED
                                      BANC OF AMERICA SECURITIES LLC
                                      BEAR, STEARNS & CO. INC.
                                      GOLDMAN, SACHS & CO.
                                      MERRILL LYNCH, PIERCE, FENNER &
                                        SMITH INCORPORATED
                                      SALOMON SMITH BARNEY INC.


                                      By:  CREDIT SUISSE FIRST BOSTON
                                             CORPORATION


                                      By:         /s/ Kristin M. Allen
                                               Name:  Kristin M. Allen
                                               Title: Managing Director




                                      -51-


                                                                      Exhibit 12


                       Ratio of Earnings to Fixed Charges

                           American Tower Corporation


The following  table reflects the  computation of the ratio of earnings to fixed
charges for the periods presented.



<TABLE>
<CAPTION>
                                        Period From July 17, 1995                                                Six Months
                                             (Incorporation)                 Year ended December 31,                Ended
                                          to December 31, 1995         1996          1997            1998       June 30, 1999
                                          --------------------         ----          ----            ----       -------------
<S>                                          <C>                     <C>           <C>            <C>              <C>
Computation of Earnings:
Loss Before Income Taxes and
Extraordinary Loss . . . . . . . . .         $  (184)                $  (434)      $  (2,049)     $  (42,441)      $  (20,130)

Add:
Interest Expense . . . . . . . . . .               -                       -           3,040          23,229           11,539
Operating Leases . . . . . . . . . .               2                     126             633           3,245            2,971
                                             -------                 -------       ---------      ----------       ----------
Earnings as Adjusted . . . . . . . .            (182)                   (308)          1,624         (15,967)          (5,620)

Computation of Fixed Charges:
Interest Expense . . . . . . . . . .               -                       -           3,040          23,229           11,539
Operating Leases . . . . . . . . . .               2                     126             633           3,245            2,971
                                             -------                 -------       ---------      ----------       ----------
Fixed Charges . . . . . . . . . . .                2                     126           3,673          26,474           14,510

Ratio of Earnings to Fixed Charges                 -                       -             .44               -                -

Deficiency in Earnings Required to
Cover Fixed Charges . . . . . . . .            $ 184                   $ 434         $ 2,049         $42,441          $20,130



<FN>
(1)     Interest  expense includes  amortization of deferred  financing costs for the year ended December 31, 1997, 1998 and the six
        months ended June 1999. Interest expense also includes redeemable  preferred stock dividends for the year ended December 31,
        1998.

(2)     For purposes of this calculation  "earnings"  consist of loss before income taxes,  extraordinary  losses and fixed charges.
        "Fixed Charges" consist of interest  expense,  amortization of debt discount and related issuance costs and the component of
        rental expense associated with operating leases believed by management to be representative of the interest  factor  thereon
        (30%).
</FN>
</TABLE>




                                                                    Exhibit 23.1

                          INDEPENDENT AUDITORS' CONSENT

We consent to the incorporation by reference in this  Registration  Statement of
American  Tower  Corporation  on Form S-3 of our  report  dated  March 4,  1999,
appearing in the Annual Report on Form 10-K of American  Tower  Corporation  for
the year ended  December  31, 1998 and to the  reference to us under the heading
"Experts" in the Prospectus, which is part of this Registration Statement.


/s/ Deloitte & Touche LLP
Boston, Massachusetts
October 18, 1999






                                                                    Exhibit 23.2

                              Accountants' Consent

The Board of Directors
UNIsite, Inc. and Subsidiaries:


We consent to the  incorporation by reference in the  registration  statement on
Form S-3 of American Tower  Corporation of our report dated March 31, 1999, with
respect to the consolidated balance sheets of UNIsite,  Inc. and Subsidiaries as
of  December  31,  1998 and 1997,  and the related  consolidated  statements  of
operations,  redeemable  convertible preferred stock and stockholders'  deficit,
and cash flows for each of the years in the three-year period ended December 31,
1998 which report  appears in the Form 8-K of American Tower  Corporation  dated
September 17, 1999.



Tampa, Florida
October 15, 1999                                       /s/ KPMG LLP






                                                                    Exhibit 23.3


                          Independent Auditors' Consent


The Board of Directors
OmniAmerica, Inc. (formerly Specialty Teleconstructors, Inc.):

We consent to the  incorporation by reference in the  registration  statement on
Form S-3 dated  October  20, 1999 of American  Tower  Corporation  of our report
dated  August 29,  1997,  with  respect  to the  consolidated  balance  sheet of
OmniAmerica,  Inc. and subsidiaries (formerly Specialty Teleconstructors,  Inc.)
as of June 30,  1997,  and the  related  consolidated  statements  of  earnings,
stockholders'  equity,  and cash flows for the year ended June 30,  1997,  which
report appears in the Form 8-K of American Tower Corporation dated September 17,
1999,  and to the  reference  to our firm  under the  heading  "Experts"  in the
prospectus.





Albuquerque, New Mexico
October 15, 1999                                        /s/ KPMG LLP












                                                                    Exhibit 23.4


We  consent to the  reference  to our firm under the  caption  "Experts"  in the
Registration  Statement  on Form S-3 and related  Prospectus  of American  Tower
Corporation for the registration of 6.25% and 2.25%  convertible  notes due 2009
and Class A common stock and to the  incorporation  by reference  therein of our
report dated  September  16, 1998,  with respect to the  consolidated  financial
statements  of   OmniAmerica,   Inc.  and   Subsidiaries   (formerly   Specialty
Teleconstructors,  Inc.) at and for the year ended June 30,  1998,  included  in
American Tower Corporation's Form 8-K.


Dallas, Texas
October 14, 1999                                     /s/ Ernst & Young LLP






                                                                    Exhibit 23.5

                         Consent of Independent Auditors


We consent to the incorporation by reference in the Registration Statement (Form
S-3 No.  333-00000) of American Tower  Corporation of our reports dated April 1,
1999 with  respect to the  financial  statements  of TeleCom  Towers,  LLC as of
December  31,  1998 and 1997 and for the year ended  December  31,  1998 and the
period  from  September  30,  1997  (inception)  to  December  31,  1997 and the
financial statements of TeleCom Towers  Mid-Atlantic,  LP, TeleCom Towers of the
West, LP and TeleCom  Southwest  Towers, LP as of July 31, 1998 and December 31,
1997 and for the seven  months  ended July 31, 1998 and the year ended  December
31, 1997, included in the Form 8-K of American Tower Corporation dated September
17, 1999, filed with the Securities and Exchange Commission.


Vienna, Virginia
October 15, 1999                                    /s/ Ernst & Young LLP






                                                                    Exhibit 23.6


                              ACCOUNTANT'S CONSENT


The Board of Directors and Stockholder
RCC Consultants, Inc.:

We consent to the use our reports,  dated February 24, 1999 incorporated  herein
by reference and to the reference to our firm under the heading "Experts" in the
prospectus.


Short Hills, New Jersey
October 15, 1999                                          /s/ KPMG LLP









                                                                    Exhibit 23.7



                    CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS


As independent  public  accountants,  we hereby consent to the  incorporation by
reference  in  this  registration  statement  on  Form  S-3  of  American  Tower
Corporation   of  our  report  dated   November  25,  1998   included  in  Wauka
Communications,  Inc.'s  financial  statements  for the period ended October 26,
1998  and to all  references  of our  Firm  included  in or  made a part of this
registration statement.



Atlanta, Georgia
October 15, 1999                                   /s/ Arthur Anderson LLP






                                                                    Exhibit 23.8

                         CONSENT OF INDEPENDENT AUDITORS

The Board of Directors
American Tower Corporation

We consent to the  incorporation by reference in the  registration  statement on
Form S-3 of  American  Tower  Corporation  dated  October 20, 1999 of our report
dated January 23, 1998, with respect to the consolidated financial statements of
American Tower  Corporation and  subsidiaries  (old ATC) as of December 31, 1997
and 1996,  and for each of the years in the three year period ended December 31,
1997, which report appears in the Form 8-K of American Tower  Corporation  dated
September 17, 1999, and to the reference to our firm under the heading "Experts"
in the prospectus.


Houston, Texas
October 18, 1999                                             /s/ KPMG LLP


                                                                      Exhibit 25

    ========================================================================
                                    FORM T-1

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                            STATEMENT OF ELIGIBILITY
                   UNDER THE TRUST INDENTURE ACT OF 1939 OF A
                    CORPORATION DESIGNATED TO ACT AS TRUSTEE

                      CHECK IF AN APPLICATION TO DETERMINE
                      ELIGIBILITY OF A TRUSTEE PURSUANT TO
                             SECTION 305(b)(2) |__|

                                  -------------

                              THE BANK OF NEW YORK
               (Exact name of trustee as specified in its charter)

  New York                                               13-5160382
  (State of incorporation                                (I.R.S. employer
  if not a U.S. national bank)                           identification no.)

  One Wall Street, New York, N.Y.                        10286
  (Address of principal executive offices)               (Zip code)

                                  -------------

                           AMERICAN TOWER CORPORATION
               (Exact name of obligor as specified in its charter)


  Delaware                                              65-0723837
  (State or other jurisdiction of                       (I.R.S. employer
  incorporation or organization)                        identification no.)

  116 Huntington Avenue
  Boston, Massachusetts                                 02116
  (Address of principal executive offices)              (Zip code)

                                  -------------

                        6.25% Convertible Notes due 2009
                        2.25% Convertible Notes due 2009
                       (Title of the indenture securities)

    ========================================================================

<PAGE>



1.       General  information.  Furnish  the  following  information  as to  the
         Trustee:

        (a) Name and address of each examining or supervising authority to which
it is subject.

- --------------------------------------------------------------------------------
                  Name                                        Address
- --------------------------------------------------------------------------------

        Superintendent of Banks of the       2 Rector Street, New York,
        State of New York                    N.Y.  10006, and Albany, N.Y. 12203

        Federal Reserve Bank of New York     33 Liberty Plaza, New York,
                                             N.Y.  10045

        Federal Deposit Insurance            Washington, D.C.  20429
        Corporation

        New York Clearing House Association  New York, New York   10005

        (b) Whether it is authorized to exercise corporate trust powers.

        Yes.

2.      Affiliations with Obligor.

        If the  obligor  is an  affiliate  of the  trustee,  describe  each such
        affiliation.

        None.

16.     List of Exhibits.

        Exhibits  identified in parentheses  below, on file with the Commission,
        are incorporated  herein by reference as an exhibit hereto,  pursuant to
        Rule  7a-29  under the Trust  Indenture  Act of 1939 (the  "Act") and 17
        C.F.R. 229.10(d).

        1.     A copy of the  Organization  Certificate  of The Bank of New York
               (formerly Irving Trust Company) as now in effect,  which contains
               the  authority  to  commence  business  and a grant of  powers to
               exercise corporate trust powers. (Exhibit 1 to Amendment No. 1 to
               Form T-1 filed with Registration Statement No. 33-6215,  Exhibits
               1a and 1b to Form  T-1  filed  with  Registration  Statement  No.
               33-21672  and  Exhibit  1 to Form  T-1  filed  with  Registration
               Statement No. 33-29637.)

        4.      A copy of the  existing  By-laws of the  Trustee.  (Exhibit 4 to
                Form T-1 filed with Registration Statement No. 33-31019.)

        6.      The  consent of the Trustee  required  by Section  321(b) of the
                Act.  (Exhibit 6 to Form T-1 filed with  Registration  Statement
                No. 33-44051.)

        7.     A copy of the latest report of condition of the Trustee published
               pursuant  to law or to the  requirements  of its  supervising  or
               examining authority.


                                      -2-
<PAGE>





                                    SIGNATURE



        Pursuant to the  requirements  of the Act, the Trustee,  The Bank of New
York, a corporation  organized  and existing  under the laws of the State of New
York,  has duly caused this  statement of eligibility to be signed on its behalf
by the undersigned,  thereunto duly authorized, all in The City of New York, and
State of New York, on the 19th day of October, 1999.


                                               THE BANK OF NEW YORK



                                               By:    /s/  MICHAEL CULHANE
                                                   Name:    MICHAEL CULHANE
                                                  Title:    VICE PRESIDENT

<PAGE>

- --------------------------------------------------------------------------------

                       Consolidated Report of Condition of

                              THE BANK OF NEW YORK

                    of One Wall Street, New York, N.Y. 10286
                     And Foreign and Domestic Subsidiaries,
a member of the Federal Reserve System,  at the close of business June 30, 1999,
published  in  accordance  with a call made by the Federal  Reserve Bank of this
District pursuant to the provisions of the Federal Reserve Act.

<TABLE>
<CAPTION>
                                                                                              Dollar Amounts
                                                                                               In Thousands
<S>                                                                                               <C>
ASSETS
Cash and balances due from depository institutions:
   Noninterest-bearing balances and currency and coin..                                           $5,597,807
   Interest-bearing balances...........................                                            4,075,775
Securities:
   Held-to-maturity securities.........................                                              785,167
   Available-for-sale securities.......................                                            4,159,891
Federal funds sold and Securities purchased under
   agreements to resell................................                                            2,476,963
Loans and lease financing receivables:
   Loans and leases, net of unearned
     income...............38,028,772
   LESS: Allowance for loan and
     lease losses............568,617
   LESS: Allocated transfer risk
     reserve........................16,352
   Loans and leases, net of unearned income,
     allowance, and reserve............................                                           37,443,803
Trading Assets.........................................                                            1,563,671
Premises and fixed assets (including capitalized
   leases).............................................                                              683,587
Other real estate owned................................                                               10,995
Investments in unconsolidated subsidiaries and
   associated companies................................                                              184,661
Customers' liability to this bank on acceptances
   outstanding.........................................                                              812,015
Intangible assets......................................                                            1,135,572
Other assets...........................................                                            5,607,019
                                                                                                ------------
Total assets...........................................                                          $64,536,926
                                                                                                 ===========

<PAGE>

LIABILITIES
Deposits:
   In domestic offices.................................                                          $26,488,980
   Noninterest-bearing.......................10,626,811
   Interest-bearing..........................15,862,169
   In foreign offices, Edge and Agreement
     subsidiaries, and IBFs............................                                           20,655,414
   Noninterest-bearing..........................156,471
   Interest-bearing..........................20,498,943
Federal funds purchased and Securities sold under
   agreements to repurchase............................                                            3,729,439
Demand notes issued to the U.S.Treasury................                                              257,860
Trading liabilities....................................                                            1,987,450
Other borrowed money:
   With remaining maturity of one year or less.........                                              496,235
   With remaining maturity of more than one year
     through three years...............................                                                  465
   With remaining maturity of more than three years....                                               31,080
Bank's liability on acceptances executed and
   outstanding.........................................                                              822,455
Subordinated notes and debentures......................                                            1,308,000
Other liabilities......................................                                            2,846,649
                                                                                                ------------
Total liabilities......................................                                           58,624,027
                                                                                                 ===========
EQUITY CAPITAL
Common stock...........................................                                            1,135,284
Surplus................................................                                              815,314
Undivided profits and capital reserves.................                                            4,001,767
Net unrealized holding gains (losses) on
   available-for-sale securities.......................                                         (      7,956)
Cumulative foreign currency translation adjustments....                                         (     31,510)
                                                                                                ------------
Total equity capital...................................                                            5,912,899
                                                                                                ------------
Total liabilities and equity capital...................                                          $64,536,926
                                                                                                 ===========
</TABLE>

<PAGE>


         I, Thomas J.  Mastro,  Senior Vice  President  and  Comptroller  of the
above-named  bank do hereby  declare  that this  Report  of  Condition  has been
prepared in conformance with the  instructions  issued by the Board of Governors
of the  Federal  Reserve  System  and is true to the  best of my  knowledge  and
belief.

                                                                Thomas J. Mastro

         We, the undersigned directors, attest to the correctness of this Report
of Condition  and declare that it has been examined by us and to the best of our
knowledge  and belief has been  prepared in  conformance  with the  instructions
issued by the Board of Governors of the Federal  Reserve  System and is true and
correct.

Thomas A. Reyni
Alan R. Griffith                                              Directors
Gerald L. Hassell


- --------------------------------------------------------------------------------



© 2022 IncJournal is not affiliated with or endorsed by the U.S. Securities and Exchange Commission