AMERICAN TOWER CORP /MA/
424B3, 1999-11-16
COMMUNICATIONS SERVICES, NEC
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                  Filed Pursuant to Rule 424(b)(3) of the Securities Act of 1933
                                                      Registration No. 333-89345


                                   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 November 2, 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
approximately 300 sites, approximately 200 of which are 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 22, 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
semiannual  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-

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