AMERICAN TOWER CORP /MA/
8-K, 1999-07-16
COMMUNICATIONS SERVICES, NEC
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                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                    FORM 8-K


                                 CURRENT REPORT

                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                Date of Report (Date of earliest event reported):
                         July 16, 1999 (June 28, 1999)

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

        Delaware                  001-14195                     65-0723837
(State or Other Jurisdiction     (Commission                  (IRS Employer
    of Incorporation)            File Number)               Identification No.)




            116 Huntington Avenue
            Boston, Massachusetts                                   02116
- --------------------------------------------------------------------------------
    (Address of Principal Executive Offices)                      (Zip Code)




                                 (617) 375-7500
            -------------------------------------------------------
              (Registrant's telephone number, including area code)





<PAGE>



Item 5.  Other Events.

         On June 28, 1999,  American Tower  Corporation (the "Company" or "ATC")
entered  into an  Agreement  and Plan of Merger (the  "Merger  Agreement")  with
UniSite, Inc. ("UniSite"), and ATI Merger Corporation, a subsidiary of ATC and a
Delaware corporation ("ATI"), pursuant to which UniSite will merge with and into
ATI, with UniSite being the surviving  corporation  (the "Merger").  UniSite was
founded in 1994 to address the challenges  associated with antenna siting and to
focus primarily on tower site  management.  Most recently,  UniSite has expanded
its scope to include site  ownership and  development.  UniSite  presently  owns
approximately   400  towers   suited  for   colocation   and  has  an  exclusive
build-to-suit  contract  with  Omnipoint  Corporation  through  the  year  2012.
Pursuant  to the  Merger  Agreement,  which  has been  approved  by the Board of
Directors of ATC and UniSite, and was approved by the stockholders of UniSite by
written consent on July 12, 1999, UniSite preferred and common stockholders will
receive an aggregate of approximately  $165 million in cash,  subject to working
capital and completed  tower closing  adjustments.  Pursuant to the Merger,  ATC
will also assume  approximately  $40 million in debt,  subject to adjustment for
interim  acquisitions  and capital  expenditures.  Consummation of the Merger is
expected  to occur on the  earlier of (a) January  31,  2000,  or (b)  UniSite's
owning and  operating  600  wireless  communication  towers,  subject to certain
conditions including,  the expiration or early termination of the waiting period
under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended.

         For more information,  see the ATC press release,  dated June 28, 1999,
which is attached herewith as Exhibit 99.1.

Item 7.  Financial Statements, Pro Forma Financial Information and Exhibits.

         (a)  Financial Statements

         In accordance with Item 7(a)(4) of Form 8-K, such financial  statements
shall be filed in a Current  Report on Form 8-K no later  than 75 days after the
consummation of the Merger.

         (b)  Pro Forma Financial Information

         As of the date of this filing of this Current Report on Form 8-K, it is
impracticable  for the  Company to provide the pro forma  financial  information
required  by this Item  7(b).  In  accordance  with Item 7(b) of Form 8-K,  such
financial  statements  shall be filed in a Form 8-K no later  than 75 days after
the consummation of the Merger.

         (c)  Exhibits

         Exhibit 2.1  -    Agreement  and Plan of  Merger,  dated as of June 28,
                           1999,  by and among  American  Tower  Corporation,  a
                           Delaware  corporation,   ATI  Merger  Corporation,  a
                           Delaware  corporation  and UniSite,  Inc., a Delaware
                           corporation.

         Exhibit 99.1  -   Press Release, dated as of June 28, 1999.




<PAGE>





                                   SIGNATURES


         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                              AMERICAN TOWER CORPORATION
                              (Registrant)


Date: July 16, 1999           By: /s/ Justin D. Benincasa
                                  Name: Justin D. Benincasa
                                  Title: Vice President and Corporate Controller









                          AGREEMENT AND PLAN OF MERGER

                                  By and Among

                           AMERICAN TOWER CORPORATION,

                             ATI MERGER CORPORATION

                                       and

                                  UNISITE, INC.

                                   Dated as of

                                  June 28, 1999














<PAGE>



<TABLE>
<CAPTION>
                                TABLE OF CONTENTS

                                                                                                               Page

<S>                                                                                                              <C>
ARTICLE 1         DEFINED TERMS...................................................................................1

ARTICLE 2         THE MERGER......................................................................................2
                  2.1      The Merger.............................................................................2
                  2.2      Closing................................................................................2
                  2.3      Effective Time.........................................................................2
                  2.4      Effect of the Merger...................................................................2
                  2.5      Certificate of Incorporation...........................................................2
                  2.6      Bylaws.................................................................................2
                  2.7      Directors and Officers.................................................................2

ARTICLE 3         CONVERSION OF SHARES; EXCHANGE OF CERTIFICATES..................................................3
                  3.1      Conversion of Capital Stock............................................................3
                  3.2      Surrender of Certificates..............................................................4
                  3.3      Stock Transfer Books...................................................................5
                  3.4      Option Securities and Convertible Securities; No Payment Rights........................5
                  3.5      Determination of Merger Consideration.  ...............................................5
                  3.6      Appraisal Rights.......................................................................6

ARTICLE 4         REPRESENTATIONS AND WARRANTIES OF UNISITE ......................................................6
                  4.1      Organization and Business; Power and Authority; Effect of Transaction..................6
                  4.2      Financial and Other Information. ......................................................8
                  4.3      Material Statements and Omissions; Absence of Events...................................8
                  4.4      Title to Properties; Leases............................................................8
                  4.5      Private Authorizations................................................................10
                  4.6      Governmental Authorizations and Applicable Law; Legal Actions.........................10
                  4.7      Intangible Assets.....................................................................11
                  4.8      Related Transactions..................................................................11
                  4.9      Insurance.............................................................................12
                  4.10     Tax Matters...........................................................................12
                  4.11     Employee Retirement Income Security Act of 1974.......................................13
                  4.12     Year 2000 Compliant...................................................................15
                  4.13     Bank Accounts, Etc....................................................................15
                  4.14     Employment and Consulting Arrangements................................................15
                  4.15     Material Agreements...................................................................16
                  4.16     Ordinary Course of Business...........................................................16
                  4.17     Material and Adverse Restrictions.....................................................17
                  4.18     Broker or Finder......................................................................17
                  4.19     Environmental Matters.................................................................17
                  4.20     Capital Stock.........................................................................19

ARTICLE 5         REPRESENTATIONS AND WARRANTIES OF ATC AND ATI..................................................19
                  5.1      Organization and Business; Power and Authority; Effect of Transaction.................19
                  5.2      ATC SEC Reports.......................................................................20
                  5.3      Material Statements and Omissions; Absence of Events..................................20
                  5.4      Broker or Finder......................................................................21
                  5.5      Legal Actions.........................................................................21
                  5.6      Absence of Change of Control..........................................................21



<PAGE>



                  5.7      Adequate Financial Resources..........................................................21

ARTICLE 6         COVENANTS......................................................................................21
                  6.1      Access to Information; Confidentiality.  .............................................21
                  6.2      Agreement to Cooperate; Certain Other Covenants.  ....................................22
                  6.3      Public Announcements..................................................................23
                  6.4      Notification of Certain Matters.......................................................23
                  6.5      Other Offers; No Solicitation.........................................................23
                  6.6      Conduct of Business by UniSite Pending the Merger.....................................25
                  6.7      Preliminary Title Reports.............................................................27
                  6.8      Environmental Site Assessments........................................................27
                  6.9      Interim Financing for UniSite; ATC Commitment.........................................28
                  6.10     Solicitation of Employees.............................................................28
                  6.11     Director and Officer Liability and Indemnification....................................29
                  6.12     UniSite Software Expertise............................................................29
                  6.13     Stockholder Approval.  ...............................................................31
                  6.14     UniSite Compensation Plan.............................................................31
                  6.15     Structural Reports....................................................................31

ARTICLE 7         CLOSING CONDITIONS.............................................................................31
                  7.1      Conditions to Obligations of Each Party...............................................31
                  7.2      Conditions to Obligations of ATC and ATI..............................................32
                  7.3      Conditions to Obligations of UniSite..................................................35

ARTICLE 8         TERMINATION, AMENDMENT AND WAIVER..............................................................36
                  8.1      Termination...........................................................................36
                  8.2      Effect of Termination.................................................................38

ARTICLE 9         SURVIVAL.......................................................................................39

ARTICLE 10        GENERAL PROVISIONS.............................................................................39
                  10.1     Waivers; Amendments...................................................................40
                  10.2     Fees, Expenses and Other Payments.....................................................40
                  10.3     Notices...............................................................................40
                  10.4     Specific Performance; Other Rights and Remedies.......................................41
                  10.5     Severability..........................................................................41
                  10.6     Counterparts..........................................................................42
                  10.7     Section Headings......................................................................42
                  10.8     Governing Law.........................................................................42
                  10.9     Further Acts..........................................................................42
                  10.10    Entire Agreement......................................................................42
                  10.11    Assignment............................................................................43
                  10.12    Parties in Interest...................................................................43
                  10.13    Mutual Drafting.......................................................................43
                  10.14    UniSite Stockholder Representatives...................................................43
                  10.15    UniSite Disclosure Schedule.  ........................................................43
                  10.16    ATC Completion of Due Diligence.  ....................................................44
</TABLE>

APPENDIX A:                Definitions


                                      -ii-

<PAGE>



EXHIBITS:

         EXHIBIT A:    Section 262 of the DCL (Section 3.6(a)).
         EXHIBIT B:    UniSite Note (Section 6.9).
         EXHIBIT C:    UniSite Security Agreement (Section 6.9).
         EXHIBIT D:    Opinion of UniSite Counsel (Section 7.2(b)).
         EXHIBIT E:    Non-Foreign Ownership Certificates (Section 7.2(i)).
         EXHIBIT F-1:  ATC [Employment] [Consulting] Agreement (Section 7.2(m)).
         EXHIBIT F-2:  ATC Noncompetition Agreement (Section 7.2(m)).
         EXHIBIT G:    Opinion of ATC and ATI Counsel (Section 7.3(b)).
         EXHIBIT H:    Omnipoint Amendment (Definition thereof in Appendix A).



                                      -iii-

<PAGE>



                          AGREEMENT AND PLAN OF MERGER


         Agreement  and Plan of Merger,  dated as of June 28, 1999, by and among
American  Tower  Corporation,   a  Delaware   corporation  ("ATC"),  ATI  Merger
Corporation,  a Delaware  corporation  ("ATI"),  and  UniSite,  Inc., a Delaware
corporation ("UniSite").

                              W I T N E S S E T H:

         WHEREAS,  the  Boards  of  Directors  of  ATC,  ATI  and  UniSite  have
determined  that the merger (the  "Merger") of ATI into UniSite on the terms and
conditions set forth in this Agreement and Plan of Merger (this  "Agreement") is
consistent with and in furtherance of the long-term  business  strategy of each,
and is  fair  to,  and in the  best  interests  of,  ATI  and  UniSite  and  the
stockholders of each; and

         WHEREAS, this Agreement provides that ATI shall be merged with and into
UniSite, and UniSite shall be the surviving corporation; and

         WHEREAS,  the Boards of Directors of ATI and UniSite have  approved and
adopted this Agreement and have directed that this Agreement be submitted to the
stockholders of ATI and UniSite,  respectively, for their adoption and approval;
and

         WHEREAS,  the Board of Directors of American  Towers,  Inc., a Delaware
corporation,  has approved and adopted this Agreement and approved the Merger as
the sole stockholder of ATI;

         NOW,   THEREFORE,   in   consideration   of  the   premises   and   the
representations, warranties, covenants and agreements herein contained and other
valuable   consideration,   the   receipt  and   adequacy   whereof  are  hereby
acknowledged,  the  parties  hereto  hereby,  intending  to  be  legally  bound,
represent, warrant, covenant and agree as follows:


                                    ARTICLE 1

                                  DEFINED TERMS

         As used  herein,  unless  the  context  otherwise  requires,  the terms
defined in  Appendix A shall have the  respective  meanings  set forth  therein.
Terms defined in the singular  shall have a comparable  meaning when used in the
plural,  and vice  versa,  and the  reference  to any gender  shall be deemed to
include all genders.  Unless otherwise  defined or the context otherwise clearly
requires,  terms for which  meanings are provided in this  Agreement  shall have
such meanings when used in the UniSite Disclosure Schedule,  and each Collateral
Document  executed  or required  to be  executed  pursuant  hereto or thereto or
otherwise delivered,  from time to time, pursuant hereto or thereto.  References
to "hereof," "herein" or similar terms are intended to refer to the Agreement as
a whole and not a particular section,  and references to "this Section" or "this
Article"  are  intended  to refer to the entire  section  or  article  and not a
particular subsection thereof. The term "either party" shall, unless the context
otherwise  requires,  refer to ATC and ATI, on the one hand, and UniSite, on the
other hand.






<PAGE>



                                    ARTICLE 2

                                   THE MERGER

         2.1 The Merger.  Upon the terms and subject to the conditions set forth
in this Agreement,  and in accordance with the Delaware General  Corporation Law
(the "DCL"),  at the Effective  Time, ATI shall be merged with and into UniSite.
As a result of the Merger, the separate  corporate  existence of ATI shall cease
and UniSite shall continue as the surviving corporation in the Merger (sometimes
referred to, as such, as the "Surviving Corporation").

         2.2 Closing.  Unless this Agreement shall have been terminated pursuant
to Section 8.1 and subject to the  satisfaction  or, to the extent  permitted by
Applicable  Law, waiver of the conditions set forth in Article 7, the closing of
the Merger (the  "Closing") will take place, at 10:00 a.m., on the Closing Date,
at the offices of  Sullivan & Worcester  LLP,  One Post Office  Square,  Boston,
Massachusetts  02109, on the earlier to occur of (a) January 31, 2000 or (b) the
fifth (5th) business day after UniSite shall have advised ATC in writing that it
has 600 Completed  Towers,  unless  another date,  time or place is agreed to in
writing by the parties.  The date on which the Closing occurs is herein referred
to as the "Closing Date."

         2.3 Effective  Time.  Subject to the provisions of this  Agreement,  as
promptly as  practicable  after the Closing,  the parties hereto shall cause the
Merger to be  consummated  by filing a  Certificate  of Merger  and any  related
filings  required  under  the DCL with the  Secretary  of State of the  State of
Delaware.  The Merger shall become  effective at such time as such documents are
duly filed as aforesaid, or at such later time as is specified in such documents
(the "Effective Time").

         2.4 Effect of the Merger.  The Merger  shall have the effects  provided
for under the DCL.

         2.5 Certificate of  Incorporation.  The Certificate of Incorporation of
UniSite,  as amended,  shall be amended and  restated to read in its entirety as
the Certificate of  Incorporation  of ATI, as in effect at immediately  prior to
the Effective  Time, and, as so amended and restated shall be the Certificate of
Incorporation of the Surviving  Corporation until thereafter amended as provided
therein and in accordance with Applicable Law.

         2.6 Bylaws. The bylaws of UniSite in effect at the Effective Time shall
be amended and  restated  to read in their  entirety as the bylaws of ATI, as in
effect  immediately prior to the Effective Time, and, as so amended and restated
shall be the bylaws of the  Surviving  Corporation  until  amended in accordance
with Applicable Law and the Organic Documents of the Surviving Corporation.

         2.7 Directors and Officers.  From and after the Effective  Time,  until
successors  are duly elected or appointed and  qualified,  or upon their earlier
resignation  or  removal,  in  accordance  with  Applicable  Law and the Organic
Documents of the Surviving  Corporation,  (a) the  directors of ATI  immediately
prior to the Effective Time shall be the directors of the Surviving Corporation,
and (b) the officers of ATI immediately prior to the Effective Time shall be the
officers of the Surviving Corporation.



                                       -2-


<PAGE>



                                    ARTICLE 3

                 CONVERSION OF SHARES; EXCHANGE OF CERTIFICATES

         3.1  Conversion of Capital Stock.  At the Effective  Time, by virtue of
the Merger and  without  any action on the part of ATC,  ATI or UniSite or their
respective stockholders:

                  (a) Each share of Common Stock,  par value $.01 per share,  of
         ATI issued and  outstanding  immediately  prior to the  Effective  Time
         shall remain outstanding as stock of the Surviving Corporation;

                  (b) Each share of Preferred  Stock,  par value $.01 per share,
         of UniSite ( the "UniSite  Preferred  Stock"),  consisting of shares of
         (i) Class A Preferred  Stock,  par value $1.00 per share (the  "UniSite
         Class A Preferred"),  (ii) Class B Preferred Stock, par value $1.00 per
         share (the "UniSite  Class B  Preferred"),  and (iii) Class C Preferred
         Stock,  par value $1.00 per share (the  "UniSite  Class C  Preferred"),
         issued and outstanding  immediately  prior to the Effective Time (other
         than  Dissenting  Shares and shares held in the  treasury of UniSite or
         any of its Subsidiaries) shall, by virtue of the Merger and without any
         action on the part of the holder  thereof,  be converted into the right
         to receive  before  payment with respect to any UniSite Common Stock or
         UniSite Warrants,  in cash, its share of the trust described below (the
         "Merger Trust"); and

                  (c) Each share (collectively,  the "UniSite Shares") of common
         stock,  par value  $.01 per  share,  of UniSite  (the  "UniSite  Common
         Stock") issued and outstanding  immediately prior to the Effective Time
         (other  than  Dissenting  Shares and  shares  held in the  treasury  of
         UniSite or any of its Subsidiaries) and each UniSite Warrant issued and
         outstanding immediately prior to the Effective Time shall, by virtue of
         the Merger and without any action on the part of the holder thereof, be
         converted  into the right to  receive  in cash its share of the  Merger
         Trust.

The term "Merger Consideration" shall mean an amount equal to the sum of:

                  (i) $25.0 million;

                  (ii) the amount derived by multiplying the number of Completed
         Towers of UniSite as of the Effective Time by $300,000;

                  (iii) increased or decreased, as the case may be, by an amount
         equal to the positive or negative  Working Capital of UniSite as of the
         Effective Time; and

                  (iv)  decreased  by an amount  equal to the  excess of (A) the
         principal  amount of Indebtedness for Money Borrowed of UniSite and its
         Subsidiaries as of the Effective Time over (B) the principal  amount of
         Indebtedness  for Money Borrowed of UniSite and its  Subsidiaries as of
         the  Effective  Time that was borrowed  subsequent  to the date of this
         Agreement and used to fund construction of towers (other than Completed
         Towers) subsequent to the date of this Agreement.

Anything  in this  Section  or  elsewhere  in  this  Agreement  to the  contrary
notwithstanding,  the Merger  Consideration  shall be  adjusted  pursuant to the
provisions of paragraphs (f), (j) and (l) of Section 7.2


                                       -3-


<PAGE>



The term "Merger  Trust" means a trust to be  established  before the  Effective
Time for the  benefit of the  holders of UniSite  Preferred  Stock,  the UniSite
Common Stock, and the UniSite  Warrants.  The trustees of the Merger Trust shall
be the UniSite  Stockholder  Representatives  or their  successors.  The parties
agree to promptly amend this Agreement  before the Effective Time to reflect the
terms of the Merger Trust upon the written  request of eiher  party,  based upon
advice of counsel, that such an amendment is advisable to effect the purposes of
this Agreement.

          At the Effective Time, all shares of UniSite Preferred Stock,  UniSite
Common Stock and the UniSite Warrants (collectively,  the "UniSite Stock") shall
no longer be  outstanding  and shall  automatically  be canceled and retired and
shall cease to exist, and certificates  and warrants  previously  evidencing any
shares of UniSite Stock (each, a "Certificate")  shall thereafter  represent the
right to receive,  upon the surrender of such  Certificate  or  Certificates  in
accordance  with the  provisions of Section 3.2, the  applicable  portion of the
Merger  Consideration to which the number of shares of UniSite Stock represented
by  such   Certificate  or  Certificates  is  entitled.   The  holders  of  such
Certificates   previously   evidencing   shares  of  UniSite  Stock  outstanding
immediately  prior to the  Effective  Time shall  cease to have any rights  with
respect  to such  UniSite  Stock,  except  as  otherwise  provided  herein or by
Applicable Law.

         3.2      Surrender of Certificates.

         (a) Promptly  after the Effective  Time,  ATC shall send or cause to be
sent a notice and letter of transmittal  form to each holder of a Certificate or
Certificates  (other  than those  representing  shares  held in the  treasury of
UniSite or any of its Subsidiaries and Dissenting Shares),  advising such holder
of the  effectiveness  of the Merger and the procedure for  surrendering of such
Certificate  for exchange into the Merger Con  sideration  payable in respect of
the UniSite Stock represented  thereby.  Each  securityholder  of UniSite,  upon
surrender of each of his  Certificates,  together with a duly executed copy of a
letter of  transmittal,  shall be  entitled  to receive  cash  representing  the
applicable portion of the Merger Consideration with respect to the UniSite Stock
represented  by  such   Certificate  or  Certificates  in  accordance  with  the
provisions of this Article, including without limitation Section 3.1.

         (b) If the Merger  Consideration (or any portion thereof) is to be paid
to a Person other than the Person in whose name the  Certificate  surrendered in
exchange  therefor is registered,  it shall be a condition to the payment of the
Merger  Consideration  that the  Certificate  so  surrendered  shall be properly
endorsed or accompanied  by appropriate  stock powers and otherwise be in proper
form for transfer,  that such  transfer  otherwise be proper and that the Person
requesting  such  transfer  pay to ATC (or its agent  (which may be the trustees
under the Merger  Trust)  appointed  as the  disbursing  agent (the  "Disbursing
Agent"))  any  transfer or other  taxes  payable by reason of the  foregoing  or
establish to the  satisfaction  of ATC that such taxes have been paid or are not
required to be paid.

         (c) In the event  any  Certificate  shall  have  been  lost,  stolen or
destroyed,  upon the making of an affidavit of that fact by the Person  claiming
such  Certificate  to be lost,  stolen or  destroyed  and  subject to such other
conditions  as the Board of Directors of the Surviving  Corporation  may impose,
ATC shall, or shall cause the Surviving Corporation, as appropriate, to issue in
exchange   for  such  lost,   stolen  or  destroyed   Certificate,   the  Merger
Consideration  deliverable in respect  thereof as determined in accordance  with
this  Article.  When  authorizing  such  issue of the  Merger  Consideration  in
exchange therefor,  the Board of Directors of the Surviving  Corporation may, in
its discretion and as a condition precedent to the issuance thereof, require the
owner of such  lost,  stolen  or  destroyed  Certificate  to give the  Surviving
Corporation  a bond or other surety in such sum as it may  reasonably  direct as
indemnity  against any Claim that may be made against the Surviving  Corporation
with respect to the Certificate alleged to have been lost, stolen or destroyed.

                                       -4-


<PAGE>




         (d) No interest or dividends  shall be paid or accrue on any portion of
the Merger Consideration.

         (e) At and after the Effective  Time, the holder of a Certificate or of
Dissenting  Shares  shall cease to have any rights as a UniSite  securityholder,
except  for,  in the  case of the  holder  of a  Certificate  or the  holder  of
Dissenting  Shares to whom the proviso in Section 3.6(a)  applies,  the right to
surrender  Certificates  in the manner  prescribed by Section 3.2(b) in exchange
for  payment  of the  Merger  Consideration,  or,  in the case of the  holder of
Dissenting  Shares,  the right to  perfect  the  right to  receive  payment  for
Dissenting Shares pursuant to Section 262 of the DCL.

         (f) Anything in this Section 3.2 or elsewhere in this  Agreement to the
contrary  notwithstanding,  no UniSite  securityholder  shall be entitled to the
Merger Consideration deliverable in respect of the UniSite Stock purported to be
owned  by him  unless  such  UniSite  securityholder  shall  have  executed  and
delivered  the  certificate  required  to be  delivered  to ATC  pursuant to the
provisions  of  Section  7.2(i),   which  may  be  included  in  the  letter  of
transmittal,  it being  understood that, the failure to deliver such certificate
will result only in such  UniSite  securityholder  being  subject to  applicable
federal and state income tax withholding.

         (g)  Anything in this  Section or  elsewhere  in this  Agreement to the
contrary notwithstanding, if, at the time that any Merger Consideration is to be
delivered to any UniSite  securityholder,  such UniSite  securityholder  has any
loans or  advances  outstanding  from  UniSite or any of its  Subsidiaries,  the
Disbursing  Agent  shall,  upon  being  advised  in writing by UniSite as to the
amount of such loans or advances,  withhold from the Merger  Consideration,  and
deliver to the Surviving  Corporation in satisfaction thereof, an amount of cash
equal to the then outstanding principal of and accrued interest (if any) on such
loans and advances.

         3.3 Stock  Transfer  Books.  At the Effective  Time, the stock transfer
books of UniSite  shall be closed,  and there  shall be no further  transfer  of
UniSite Stock thereafter on the records of UniSite.  Any Certificates  presented
after the  Effective  Time for transfer  shall be canceled and exchanged for the
applicable  portion  of the  Merger  Consideration  to which the  UniSite  Stock
represented thereby shall be entitled pursuant to this Article.

         3.4 Option Securities and Convertible Securities; No Payment Rights. At
the  Effective  Time,  except in the case of a UniSite  Warrant or a Convertible
Security  or  an  Option  Security  owned  by  a  Subsidiary  of  UniSite,  each
outstanding  Option Security and each Convertible  Security of UniSite,  if any,
whether or not then exercisable for or convertible into shares of UniSite Common
Stock  or  other  UniSite  securities,  outstanding  immediately  prior  to  the
Effective Time,  shall be canceled and retired and shall cease to exist, and the
holder thereof shall not be entitled to receive any consideration therefor.

         3.5 Determination of Merger Consideration. Not later than ten (10) days
prior  to  the  Closing  Date,  UniSite  shall  submit  to ATC  its  preliminary
determination of the amount of the Merger Consideration determined in accordance
with the provisions of Section 3.1. Within seven (7) days thereafter,  ATC shall
submit to  UniSite  its  reasonable,  good  faith  objections,  if any,  to such
preliminary  determination,  specifying in reasonable  detail the nature of such
objections. The parties shall use their best efforts to agree upon the amount of
the Merger  Consideration,  but in the event they are unable to do so,  then (a)
the Merger shall be  consummated  (assuming  that all other  conditions  thereto
shall have been satisfied),  (b) the consideration payable at the Effective Time
(the "Preliminary Merger  Consideration") shall be determined by ATC and paid in
cash, subject to a post-Effective Time adjusting payment (if any) payable by ATC
to the UniSite  securityholders  as provided in this  Section.  In the event the
parties   are   unable  to  agree  as   aforesaid,   the   UniSite   Stockholder
Representatives  and ATC shall,  within ten (10) days  following  the  Effective
Time, jointly

                                       -5-


<PAGE>



designate a nationally known  independent  public accounting firm to be retained
to determine the amount of the Merger Consideration, which shall be no less than
the Preliminary Merger  Consideration.  The fees and other expenses of retaining
such  independent  public  accounting firm shall be borne by ATC and the UniSite
securityholders  in inverse proportion to its allocation of the contested amount
of  the  Merger   Consideration   to  ATC  and  the   UniSite   securityholders,
respectively.  Such firm shall report its conclusions  pursuant to this Section,
and such report shall be  conclusive  on all parties to this  Agreement  and the
UniSite securityholders and not subject to dispute or review. Upon determination
by such  independent  accounting  firm (or  sooner  agreement  upon  the  Merger
Consideration by ATC and the UniSite Stockholder Representatives), ATC shall pay
to the UniSite securityholders, as their interests may appear, the cash, if any,
to which they are  entitled,  together  with  interest of five  percent (5%) per
annum from the Closing Date to such payment.

         3.6 Appraisal Rights.

         (a)  Notwithstanding  any  other  provision  of this  Agreement  to the
contrary,  shares of UniSite Common Stock that are outstanding immediately prior
to the Effective Time and that are held by UniSite  stockholders  who shall have
not voted in favor of the Merger or  consented  thereto in writing and who shall
be entitled to and shall have demanded  properly in writing appraisal rights for
such shares of UniSite Stock in accordance  with Section 262 of the DCL (a true,
correct and  complete  copy of which is attached  hereto as Exhibit A and made a
part  hereof) and who shall not have  withdrawn  such demand or  otherwise  have
forfeited appraisal rights (collectively,  the "Dissenting Shares") shall not be
converted  into or  represent  the right to  receive  the  Merger  Consideration
payable in respect of each share of  UniSite  Stock  represented  thereby.  Such
UniSite stockholders shall be entitled to receive payment of the appraised value
of such shares of UniSite Stock held by them in accordance  with the  provisions
of the DCL, except that all Dissenting  Shares held by UniSite  stockholders who
shall have failed to perfect or who effectively shall have withdrawn,  forfeited
or lost their  appraisal  rights with  respect to such shares of UniSite  Common
Stock under the DCL shall thereupon be deemed to have been converted into and to
have become  exchangeable  for, as of the Effective  Time, the right to receive,
without  any  interest  thereon,   the  appropriate  Merger  Consideration  upon
surrender,  in the  manner  provided  in  Section  3.2,  of the  Certificate  or
Certificates that formerly evidenced such shares of UniSite Stock.

         (b) UniSite  shall give ATC prompt  notice of any demands for appraisal
rights received by it,  withdrawals of such demands,  and any other  instruments
served pursuant to the DCL and received by UniSite and relating thereto. UniSite
and ATC shall jointly direct all  negotiations  and proceedings  with respect to
demands for appraisal rights under the provisions of the DCL. UniSite shall not,
except with the prior  written  consent of ATC, make any payment with respect to
any  demands  for  appraisal  rights,  or offer to settle,  or settle,  any such
demands.


                                    ARTICLE 4

                   REPRESENTATIONS AND WARRANTIES OF UNISITE

         UniSite hereby represents and warrants to ATC and ATI as follows:

         4.1  Organization  and  Business;   Power  and  Authority;   Effect  of
Transaction.

         (a) UniSite is a corporation  duly organized,  validly  existing and in
good standing  under the DCL, has all requisite  power and authority  (corporate
and other) to own or hold under lease its properties and to conduct its business
as now  conducted  and is duly  qualified  and in  good  standing  as a  foreign
corporation in

                                       -6-


<PAGE>



each other  jurisdiction  (as shown on Section 4.1(a) of the UniSite  Disclosure
Schedule) in which the  character  of the property  owned or leased by it or the
nature of its business or  operations  requires such  qualification,  except for
such  qualifications  the  failure  of which to obtain,  individually  or in the
aggregate, have not had and will not have a material adverse effect on UniSite.

         (b) UniSite has all requisite power and authority (corporate and other)
necessary  to enable it to execute and deliver,  and to perform its  obligations
under,  this Agreement and each Collateral  Document  executed or required to be
executed by it pursuant  hereto or thereto and to consummate  the  Transactions;
and the  execution,  delivery and  performance  by UniSite of this Agreement and
each  Collateral  Document  executed  or  required to be executed by it pursuant
hereto or thereto have been duly authorized by all requisite  corporate or other
action  on the  part  of  UniSite,  subject  to the  requisite  approval  of the
stockholders  of  UniSite.  The  affirmative  vote  of  the  holders  of  shares
representing  a  majority  of the  outstanding  voting  power of each of (i) the
UniSite  Class A Preferred  Stock and the Class B Preferred  Stock,  voting as a
single class,  (ii) the UniSite Class C Preferred  Stock,  and (iii) the UniSite
Common Stock is the only vote  necessary to approve and adopt this Agreement and
the  transactions  contemplated by this Agreement.  This Agreement has been duly
executed and delivered by UniSite and constitutes,  and each Collateral Document
executed or  required  to be  executed  by it  pursuant  hereto or thereto or to
consummate  the  Transactions  when  executed  and  delivered  by  UniSite  will
constitute,  legal,  valid and binding  obligations  of UniSite,  enforceable in
accordance with their respective  terms,  except as such  enforceability  may be
subject to  bankruptcy,  moratorium,  insolvency,  reorganization,  arrangement,
voidable preference, fraudulent conveyance and other similar Laws relating to or
affecting  the rights of creditors  and except as the same may be subject to the
effect of general principles of equity.

         (c) Except as set forth in  Section  4.1(c) of the  UniSite  Disclosure
Schedule, neither the execution and delivery by UniSite of this Agreement or any
Collateral Document executed or required to be executed by it pursuant hereto or
thereto,  nor the  consummation  of the  Transactions,  nor compliance  with the
terms, conditions and provisions hereof or thereof by UniSite:

                  (i) will conflict with, or result in a breach or violation of,
         or constitute a default under,  any Organic  Document of UniSite or any
         Applicable  Law,  or will  conflict  with,  or  result  in a breach  or
         violation of, or constitute a default under, or permit the acceleration
         of any obligation or liability in, or but for any requirement of giving
         of notice or passage of time or both would  constitute  such a conflict
         with,  breach or  violation  of, or default  under,  or permit any such
         acceleration in, any Contractual Obligation of UniSite; or

                  (ii) will require  UniSite to make or obtain any  Governmental
         Authorization, Governmental Filing or Private Authorization, except (A)
         filings  under the  Hart-Scott-Rodino  Act,  and (B) the  filing of the
         Certificate of Merger with the Delaware Secretary of State.

         (d) Except as set forth in  Section  4.1(d) of the  UniSite  Disclosure
Schedule, UniSite does not have any Subsidiaries. Each such disclosed Subsidiary
is (i)  wholly-owned  unless noted  otherwise  in Section  4.1(d) of the UniSite
Disclosure  Schedule,  (ii) a  corporation  which  is  duly  organized,  validly
existing and in good standing under the laws of the state of  incorporation  set
forth  opposite its name on Section 4.1(d) of the UniSite  Disclosure  Schedule,
and (iii) duly  qualified and in good standing as a foreign  corporation in each
other  jurisdiction  (as  shown on  Section  4.1(d)  of the  UniSite  Disclosure
Schedule) in which the  character  of the property  owned or leased by it or the
nature of its business or  operations  requires  such  qualification,  with full
power and authority  (corporate  and other) to carry on the business in which it
is  engaged,  except  for such  qualifications  the  failure of which to obtain,
individually  or in the aggregate,  would not have a material  adverse effect on
UniSite.  UniSite owns,  directly or indirectly,  all of the outstanding capital
stock and equity interests

                                       -7-


<PAGE>



(as  shown  in  Section  4.1(d)  of the  UniSite  Disclosure  Schedule)  of each
Subsidiary, free and clear of all Liens (except as described in the notes to the
UniSite Financial Statements),  and all such stock or other equity interests has
been duly  authorized  and validly  issued and is fully paid and  nonassessable.
Except as set forth in Section 4.1(d) of the UniSite Disclosure Schedule,  there
are no outstanding Option Securities or Convertible Securities, or agreements or
understandings of any nature whatsoever, relating to the authorized and unissued
or outstanding  capital stock or equity  interests of any Subsidiary of UniSite.
No Subsidiary of UniSite owns any UniSite Preferred Stock,  UniSite Common Stock
or  Convertible  Security or Option  Security of UniSite.  Except as the context
otherwise  requires,  the representations and warranties of UniSite set forth in
this  Article  shall apply to each of its  Subsidiaries  with the same force and
effect as though each of them were named in each Section hereof.

         4.2  Financial  and Other  Information.  UniSite  has  heretofore  made
available to ATC the financial  statements  listed in Section 4.2 of the UniSite
Disclosure Schedule (the "UniSite Financial Statements").  The UniSite Financial
Statements,  including  in each case the notes  thereto,  have been  prepared in
accordance  with GAAP  applied on a  consistent  basis  throughout  the  periods
covered  thereby,  except as otherwise  noted  therein,  and fairly  present the
financial  condition and the results of operations and cash flow of UniSite,  on
the bases  therein  stated,  as of the  respective  dates  thereof,  and for the
respective periods covered thereby subject,  in the case of unaudited  financial
statements,  to normal nonmaterial  year-end audit  adjustments.  UniSite has no
material  obligations,   liabilities  or  commitments  of  any  nature  (whether
absolute,  accrued,  contingent or otherwise and whether  matured or unmatured),
including without limitation Tax liabilities due or to become due that should be
reflected or reserved  against in financial  statements  prepared in  conformity
with GAAP,  except  liabilities  that are reflected and reserved  against on the
UniSite Financial  Statements.  Neither UniSite nor any of the UniSite Assets is
the subject of any pending or, to  UniSite's  knowledge,  threatened  insolvency
proceedings of any kind or character. UniSite has not made an assignment for the
benefit of creditors or taken any action with a view to or that would constitute
a valid basis for the institution of any such insolvency proceedings. UniSite is
not  insolvent  and will not become  insolvent as a result of entering into this
Agreement.

         4.3 Material Statements and Omissions;  Absence of Events.  Neither any
representation or warranty made by UniSite contained in this Agreement or in any
certificate,  document  or other  instrument  furnished  or to be  furnished  by
UniSite pursuant to the provisions  hereof nor the UniSite  Disclosure  Schedule
contains or will  contain any untrue  statement  of a material  fact or omits or
will omit to state any material fact  required to make any  statement  contained
herein or therein, in light of the circumstances under which they were made, not
misleading.  Since the date of the most recent financial statements constituting
a part of the UniSite Financial Statements there has been no change with respect
to, and there is no Event known to, UniSite that has had or will have a material
adverse effect on UniSite,  except (a) to the extent  specifically  described in
Section 4.3 of the UniSite  Disclosure  Schedule,  (b) for matters affecting the
tower communication sites industry generally,  and (c) for any Event arising out
of the execution or public announcement of this Agreement.  UniSite is not aware
of  any   impending  or   contemplated   Event  that  would  cause  any  of  the
representations  and  warranties  made by it in  this  Article  not to be  true,
correct and complete on the date of such Event as if made on that date.

         4.4 Title to Properties; Leases.

         (a) Section 4.4(a) of the UniSite Disclosure  Schedule contains a true,
accurate and complete description of all real property owned by UniSite.  Except
as set forth in Section 4.4(a) of the UniSite Disclosure  Schedule,  UniSite has
good  indefeasible,  marketable and insurable  title to all real property (other
than easement and leasehold real property) and good  indefeasible and marketable
title  to all  of  its  other  property  and  assets,  tangible  and  intangible
(collectively, the "UniSite Assets"); all of the UniSite Assets are

                                       -8-


<PAGE>



so owned, in each case, free and clear of all Liens, except (i) Permitted Liens,
and (ii) Liens set forth on Section 4.4(a) of the UniSite  Disclosure  Schedule.
UniSite enjoys peaceful and undisturbed possession of all real property owned by
it.  Except  for  financing  statements  evidencing  Liens  referred  to in  the
immediately   preceding  sentence  (a  true,  accurate  and  complete  list  and
description  of which is set forth in Section  4.4(a) of the UniSite  Disclosure
Schedule),  no financing  statements  under the Uniform  Commercial  Code and no
other filing which names  UniSite as debtor or which covers or purports to cover
any of the  UniSite  Assets is on file in any state or other  jurisdiction,  and
UniSite has not signed or agreed to sign any such financing  statement or filing
or any  agreement  authorizing  any secured  party  thereunder  to file any such
financing statement or filing. None of the fixed assets or equipment  comprising
a part of the UniSite  Assets is subject to contracts of sale,  and none is held
by  UniSite  as  lessee  or as  conditional  sales  vendee  under  any  Lease or
conditional sales contract and none is subject to any title retention agreement,
except as set forth in Section 4.4(a) of the UniSite Disclosure Schedule. Except
as  disclosed  in  Section  4.4(a)  of  the  UniSite  Disclosure  Schedule,  all
improvements  on the real property  owned or leased by UniSite are in compliance
with  applicable  zoning,  wetlands  and  land use  Laws  and  applicable  title
covenants,  conditions,  restrictions and reservations in all respects necessary
to conduct  the  business  of UniSite  (the  "UniSite  Business")  as  presently
conducted or proposed to be conducted  on or prior to the Closing  Date,  except
for any  instances  of  non-compliance  which  do not and  will  not  materially
adversely  affect  the use of such  real  property  or,  individually  or in the
aggregate,  have a material  adverse effect on the owner or lessee,  as the case
may be, of such real  property.  Except as  disclosed  in Section  4.4(a) of the
UniSite Disclosure Statement,  all such improvements are structurally sound with
no material defects and comply in all material aspects with all Applicable Laws,
Governmental  Authorizations and Private Authorizations.  Except as disclosed in
Section 4.4(a) of the UniSite Disclosure Statement, to UniSite's knowledge,  all
of the transmitting  towers,  microwave stations,  ground radials,  guy anchors,
transmitting  buildings and related  improvements,  if any,  located on the real
property owned or leased by UniSite are located  entirely on such real property.
Except as set forth in Section 4.4(a) of the UniSite Disclosure  Schedule,  such
transmitting   towers,   microwave  stations,   ground  radials,   guy  anchors,
transmitting  buildings and related  improvements  and other  material  items of
personal  property,  including  equipment,  are in a state  of good  repair  and
maintenance and sound operating condition,  normal wear and tear excepted,  have
been maintained in a manner  consistent in all material  respects with generally
accepted  standards of sound  engineering  practice,  and  currently  permit the
UniSite Business to be operated in all material  respects in accordance with the
terms and conditions of all Applicable  Laws,  Governmental  Authorizations  and
Private Authorizations.

         There  is  no  pending  or,  to  UniSite's  knowledge,   threatened  or
contemplated  action (i) to take by eminent  domain or  otherwise to condemn any
material  part of any real  property  owned or leased by  UniSite,  or (ii) with
respect to any special Taxes or assessments or planned public  improvements that
may result in a special Tax or  assessment  against any real  property  owned or
leased by  UniSite,  and no such  special  Taxes or  assessments  have been made
against any real property owned or leased by UniSite. All utilities necessary to
the operation of the UniSite Assets and the conduct of the UniSite  Business are
installed and operating as part of the UniSite Assets.  To UniSite's  knowledge,
none of the real property  constituting  a part of the UniSite Assets is listed,
or eligible to be listed,  in any national,  state or local register of historic
places or areas.

         (b) Section 4.4(b) of the UniSite Disclosure  Schedule contains a true,
accurate  and  complete  description  or list of all Leases under which any real
property is leased to UniSite by any Person or by UniSite to any Person.  Except
as otherwise  set forth in Section  4.4(b) of the UniSite  Disclosure  Schedule,
each Lease under which UniSite holds real or personal  property  constituting  a
part  of the  UniSite  Assets  is in  full  force  and  effect,  has  been  duly
authorized, executed and delivered by UniSite and, to its knowledge, each of the
other parties thereto,  and is a legal, valid and binding obligation of UniSite,
and,  to its  knowledge,  each of the  other  parties  thereto,  enforceable  in
accordance with its terms, except as such enforceability may be limited

                                       -9-


<PAGE>



by bankruptcy,  moratorium, insolvency and similar Laws affecting the rights and
remedies  of  creditors  and  obligations  of debtors  generally  and by general
principles  of equity.  UniSite  has a valid  leasehold  interest  in and enjoys
peaceful and undisturbed  possession under all Leases pursuant to which it holds
any such real property or tangible  personal  property,  subject to the terms of
each Lease and  Applicable  Law. True,  accurate and complete  copies of each of
such Leases have been made  available by UniSite to ATC and UniSite has provided
ATC with photocopies of all such Leases requested by ATC (or true,  accurate and
complete  descriptions  thereof  have  been set forth in  Section  4.4(b) of the
UniSite  Disclosure  Schedule,  with  respect to those  that are oral).  Neither
UniSite nor, to UniSite's knowledge,  any other party thereto has failed to duly
comply with all of the material  terms and  conditions of each such Lease or has
done or  performed,  or failed to do or perform  (and no Claim is pending or, to
the  knowledge  of UniSite,  threatened  to the effect  that  UniSite has not so
complied,  done and  performed  or failed to do and perform) any act which would
invalidate or provide  grounds for the other party thereto to terminate (with or
without  notice,  passage of time or both) any of such Leases or in any material
respect  impair the rights or benefits of, or materially  increase the costs to,
UniSite under any of such Leases.

         4.5  Private  Authorizations.  Section  4.5 of the  UniSite  Disclosure
Schedule sets forth a true,  accurate and complete list and  description of each
Private  Authorization  which  individually is material to the UniSite Assets or
the UniSite Business.  UniSite has obtained all Private  Authorizations that are
necessary for the ownership or operation of the UniSite Assets or the conduct of
the UniSite Business,  as currently  conducted or proposed to be conducted on or
prior to the  Closing  Date,  which,  if not  obtained  and  maintained,  could,
individually or in the aggregate, have a material adverse effect on UniSite. All
of such Private  Authorizations  are valid and in good  standing and are in full
force and  effect.  UniSite is not in  material  breach or  violation  of, or in
default in the  performance,  observance  or  fulfillment  of, any such  Private
Authorization,  and, to  UniSite's  knowledge,  no Event  exists or has occurred
which constitutes,  or but for any requirement of giving of notice or passage of
time or both would  constitute,  such a material  breach,  violation or default,
under any such  Private  Authorization.  No such  Private  Authorization  is the
subject of any pending or, to UniSite's knowledge, threatened attack, revocation
or termination.

         4.6 Governmental Authorizations and Applicable Law; Legal Actions.

         (a) Section 4.6(a) of the UniSite Disclosure  Schedule contains a true,
complete  and  accurate  description   (including  the  term  thereof)  of  each
Governmental  Authorization required under Applicable Law (i) to own and operate
the UniSite Assets and conduct the UniSite Business,  as currently  conducted or
proposed  to be  conducted  on or prior to the  Closing  Date,  or (ii)  that is
necessary to permit UniSite to execute and deliver this Agreement and to perform
its obligations hereunder.  Except as set forth in Section 4.6(a) of the UniSite
Disclosure Schedule,  UniSite has obtained all Governmental  Authorizations that
are  necessary  for the  ownership  or  operation  of the UniSite  Assets or the
conduct of the UniSite  Business as now conducted and which, if not obtained and
maintained,  could,  individually or in the aggregate,  have a material  adverse
effect on UniSite.  None of such  Governmental  Authorizations is subject to any
restriction or condition that could limit in any material  respect the ownership
or  operations of the UniSite  Assets or the conduct of the UniSite  Business as
currently conducted, except for restrictions and conditions generally applicable
to Governmental  Authorizations  of such type. The  Governmental  Authorizations
listed in Section  4.6(a) of the UniSite  Disclosure  Schedule  are valid and in
good standing, are in full force and effect and are not impaired in any material
respect by any act or omission of UniSite or its officers, directors,  employees
or agents, and the ownership and operation of the UniSite Assets and the conduct
of the UniSite  Business are in  accordance  in all material  respects  with the
Governmental Authorizations. All material reports, forms and statements required
to be filed by UniSite with all Authorities with respect to the UniSite Business
have been filed and are true, complete and accurate in all material respects. No
such Governmental Authorization is the subject

                                      -10-


<PAGE>



of any pending or, to UniSite's knowledge,  threatened  challenge,  complaint or
proceeding,  and no petitions to deny,  objections or other challenges have been
filed with any Authority  against any pending  application of UniSite that would
have a material adverse effect on UniSite. UniSite has no reason to believe that
any such Governmental  Authorization  will not be renewed in the name of UniSite
by the granting Authority in the ordinary course.

         (b) Except as otherwise specifically set forth in Section 4.6(b) of the
UniSite Disclosure Schedule, since January 1, 1996, UniSite has conducted and is
conducting  its business and owned and has operated and is owning and  operating
its  property  and assets in  accordance  with all  Applicable  Laws  (excluding
Environmental   Laws)  and  Governmental   Authorizations,   including   without
limitation  all  tariff and  reporting  requirements,  telecommunications  relay
service   funding   obligations,   universal   service   funding  and  reporting
requirements,  and FAA antenna  tower  requirements,  except for such  breaches,
violations and defaults as,  individually or in the aggregate,  have not had and
will  not have a  material  adverse  effect  on  UniSite.  Except  as  otherwise
specifically  described in Section  4.6(b) of the UniSite  Disclosure  Schedule,
UniSite is not in and is not charged by any  Authority  with,  and, to UniSite's
knowledge,  is not  threatened  or under  investigation  by any  Authority  with
respect  to,  any  breach  or  violation  of,  or  default  in the  performance,
observance or  fulfillment  of, any Applicable Law relating to the ownership and
operation of the UniSite  Assets or the conduct of the UniSite  Business  which,
individually or in the aggregate, has had or will have a material adverse effect
on UniSite.  Except as otherwise specifically described in Section 4.6(b) of the
UniSite Disclosure Schedule, no Event exists or has occurred, which constitutes,
or but for any  requirement of giving of notice or passage of time or both would
constitute,  such  a  breach,  violation  or  default,  under  any  Governmental
Authorization  or any Applicable  Law,  except for such breaches,  violations or
defaults as, individually or in the aggregate,  have not had and will not have a
material adverse effect on UniSite. With respect to matters, if any, of a nature
referred to in Section  4.6(b) of the  UniSite  Disclosure  Schedule,  except as
otherwise  specifically  described in Section  4.6(b) of the UniSite  Disclosure
Schedule,  all such information and matters set forth in the UniSite  Disclosure
Schedule,  if  adversely  determined  against  UniSite,  individually  or in the
aggregate, will not have a material adverse effect on UniSite.

         (c) Except as set forth in  Section  4.6(c) of the  UniSite  Disclosure
Schedule, there are no Legal Actions of any kind pending or, to the knowledge of
UniSite, threatened at Law, in equity or before any Authority against UniSite or
any of its officers or directors  relating to the  ownership or operation of the
UniSite Assets or the conduct of the UniSite Business.  All such disclosed Legal
Actions, if determined  adversely to UniSite,  individually or in the aggregate,
will not have a material adverse effect on UniSite.

         4.7 Intangible Assets.  Section 4.7 of the UniSite Disclosure  Schedule
sets forth a true, accurate and complete  description of all material Intangible
Assets  (other than  Governmental  Authorizations  and  Private  Authorizations)
relating to the ownership and operation of the UniSite  Assets or the conduct of
the UniSite Business held or used by UniSite,  including without  limitation the
nature of UniSite's  interest in each and the extent to which the same have been
duly  registered  in the offices as  indicated  therein.  Except as set forth in
Section 4.7 of the UniSite  Disclosure  Schedule,  no Intangible  Assets (except
Governmental Authorizations,  Private Authorizations,  and the Intangible Assets
so set forth) are required for the ownership or operation of the UniSite  Assets
or the  conduct  of the  UniSite  Business  as  currently  owned,  operated  and
conducted  or proposed to be owned,  operated  and  conducted on or prior to the
Closing Date.  UniSite does not, to its knowledge,  wrongfully  infringe upon or
unlawfully  use any Intangible  Assets owned or claimed by another,  and UniSite
has not  received any notice of any claim or  infringement  relating to any such
Intangible Asset.

         4.8  Related  Transactions.  UniSite  is not a party or  subject to any
Contractual  Obligation  relating to the  ownership  or operation of the UniSite
Assets or the conduct of the UniSite Business between UniSite

                                      -11-


<PAGE>



and any of its officers or directors or, to the knowledge of UniSite, any member
of  the  Immediate  Family  of  any  thereof,  or  any  Affiliate  of any of the
foregoing, including without limitation any Contractual Obligation providing for
the  furnishing of services to or by,  providing  for rental of property,  real,
personal or mixed,  to or from,  or  providing  for the lending or  borrowing of
money to or from or otherwise  requiring  payments to or from,  any such Person,
other than (a)  Employment  Arrangements  listed or described in Section 4.14 of
the UniSite Disclosure Schedule, (b) Contractual Obligations between UniSite and
any of the foregoing, that will be terminated, at no cost or expense to UniSite,
prior to the  Closing,  or (c) as  specifically  set forth in Section 4.8 of the
UniSite Disclosure Schedule.

         4.9 Insurance. UniSite maintains policies of fire and extended coverage
and casualty, liability and other forms of insurance in such amounts and against
such risks and losses as are set forth in Section 4.9 of the UniSite  Disclosure
Schedule.

         4.10 Tax  Matters.  Except as set forth in Section  4.10 of the UniSite
Disclosure Schedule:

                  (a) UniSite has in accordance  with all Applicable  Laws filed
         all Tax Returns  which are required to be filed,  and has paid, or made
         adequate  provision  for the  payment  of, all Taxes  which have or may
         become  due and  payable  pursuant  to said Tax  Returns  and all other
         governmental  charges and assessments received to date other than those
         Taxes being  contested in good faith for which  adequate  provision has
         been made on the most recent  balance sheet forming part of the UniSite
         Financial Statements;

                  (b) The Tax  Returns  of  UniSite  have been  prepared  in all
         material respects in accordance with all Applicable Laws;

                  (c) All Taxes which UniSite is required by Law to withhold and
         collect have been duly withheld and collected, and have been paid over,
         in a timely  manner,  to the proper  Authorities  to the extent due and
         payable, and UniSite is in compliance with, and its records contain all
         information  and  documents  necessary to comply with,  all  applicable
         information, reporting and Tax withholding requirements;

                  (d)  UniSite  has  not  executed  any  waiver  to  extend,  or
         otherwise taken or failed to take any action that would have the effect
         of extending,  the applicable  statute of limitations in respect of any
         Tax  liabilities  of  UniSite  for  the  fiscal  periods  prior  to and
         including the most recent fiscal year. Adequate provision has been made
         on the most recent balance sheet forming part of the UniSite  Financial
         Statements for all Taxes accrued through the date of such balance sheet
         of any kind,  including  interest  and  penalties  in respect  thereof,
         whether disputed or not, and whether past, current or deferred, accrued
         or unaccrued,  fixed,  contingent,  absolute or other, and there are no
         past  transactions or matters which could result in additional Taxes of
         a material nature to UniSite for which an adequate reserve has not been
         provided on such balance sheet;

                  (e) UniSite has at all times been  taxable as a  subchapter  C
         corporation  under  the  Code,  and  has  never  been a  member  of any
         consolidated group for Tax purposes;

                  (f)  Immediately  preceding the Merger,  UniSite will not have
         any material amount of deferred income or gain under Regulation Section
         1.1502-13 or any material excess loss account under Regulation  Section
         1.1502-19;


                                      -12-


<PAGE>



                  (g)  UniSite is not a party to any Tax  sharing  agreement  or
         arrangement;

                  (h)  UniSite  (i) has not made or entered  into,  and holds no
         assets  subject to, a consent filed  pursuant to Section  341(f) of the
         Code or a "safe  harbor  lease"  subject  to Section  168(f)(8)  of the
         Internal  Revenue  Code of 1954,  as amended and in effect prior to the
         enactment of the Tax Equity and Fiscal Responsibility Act of 1982, (ii)
         is not  required  to include  in income  any  amount for an  adjustment
         pursuant  to  Section  481 of the Code or the  regulations  thereunder,
         (iii) is not a party to, and is not obligated  under,  any agreement or
         other arrangement providing for the payment of any amount that would be
         an "excess parachute payment"under Section 280G of the Code;

                  (i) Section 4.10 of the UniSite Disclosure  Schedule describes
         all material  federal  income Tax  elections,  consents and  agreements
         affecting  UniSite  and lists all types of Taxes  paid and Tax  returns
         filed by UniSite.

                  (j) All record  and  beneficial  holders of UniSite  Preferred
         Stock and UniSite Common Stock are "United States  persons"  within the
         meaning of Section 7701(a)(30) of the Code.

         4.11 Employee  Retirement  Income  Security Act of 1974.  Except as set
forth in Section 4.11 of the UniSite Disclosure Schedule

         (a) UniSite (which for purposes of this Section shall include any ERISA
Affiliate)  has not within the  preceding  six years  sponsored,  maintained  or
contributed to, and does not currently  sponsor,  maintain or contribute to, any
Plan or  Benefit  Arrangement,  except as set forth in  Section  4.11(a)  of the
UniSite  Disclosure  Schedule.  UniSite has  delivered or made  available to ATC
true,  complete and correct copies of (i) each Plan and Benefit Arrangement (or,
in  the  case  of  any  unwritten  Plans  or  Benefit  Arrangements,  reasonable
descriptions  thereof),  (ii) the two most  recent  annual  reports on Form 5500
(including  all  schedules  and  attachments  thereto)  filed with the  Internal
Revenue  Service with respect to each Plan or Benefit  Arrangement  (if any such
report was  required by  Applicable  Law),  (iii) the two most recent  financial
statements  and  actuarial  reports  with  respect  to any Plan for  which  such
statements or reports exist,  (iv) the most recent summary plan  description (or
similar  document)  for each Plan for which such a summary plan  description  is
required by Applicable  Law or was otherwise  provided to plan  participants  or
beneficiaries,  (v) the  most  recent  Internal  Revenue  Service  determination
letter,  if any, and (vi) each trust agreement and insurance  policy  (including
any fiduciary  liability policy or bond) or annuity contract or other funding or
financing  arrangement  relating to any Plan. To the knowledge of UniSite,  each
such Form 5500 and summary plan  description (or similar  document) does not, as
of the  date  hereof,  contain  any  material  misstatements.  UniSite  does not
maintain and does not have any  obligation or liability with respect to any Plan
or other arrangement that provides for post-retirement  medical, dental, health,
hospitalization,  disability,  life insurance or other  benefits,  except as the
provisions of COBRA may apply to any former employees of UniSite.  Except as set
forth in Section 4.11(a) of the UniSite Disclosure Schedule, as to all Plans and
Benefit  Arrangements  listed  in  Section  4.11(a)  of the  UniSite  Disclosure
Schedule:

                  (i) all such Plans and  Benefit  Arrangements  comply and have
         been administered in form and in operation,  in all material  respects,
         in accordance with their  respective terms and with all Applicable Laws
         and UniSite has not received any notice from any Authority disputing or
         investigating such compliance;

                  (ii)  none of the  assets  of any such  Plan are  invested  in
         employer securities or employer real property;

                                      -13-


<PAGE>




                  (iii)  there are no Claims  (other  than  routine  Claims  for
         benefits  or actions  seeking  quali fied  domestic  relations  orders)
         pending or, to UniSite's knowledge,  threatened involving such Plans or
         the assets of such Plans, and, to UniSite's  knowledge,  no facts exist
         which are reasonably likely to give rise to any such Claims (other than
         routine  Claims for  benefits  or actions  seeking  qualified  domestic
         relations orders);

                  (iv) all  material  contributions  to, and  material  payments
         from, the Plans and Benefit Arrangements that may have been required to
         be  made  in  accordance  with  the  terms  of the  Plans  and  Benefit
         Arrangements,  and any applicable collective bargaining agreement, have
         been made. All such  contributions to, and payments from, the Plans and
         Benefit  Arrangements,  except  those  payments to be made from a trust
         qualified  under  Section  401(a) of the Code,  for any  period  ending
         before the Closing Date that are not yet,  but will be,  required to be
         made, will be properly accrued and reflected on the financial books and
         records of UniSite;

                  (v) to UniSite's knowledge,  no Event has occurred which would
         result in  imposition  on UniSite  (or on any Person  who  UniSite  has
         agreed to  indemnify)  of (A) any breach of  fiduciary  duty  liability
         damages  under  Section  409 of  ERISA,  (B) a civil  penalty  assessed
         pursuant to subsections  (c), (i) or (l) of Section 502 of ERISA or (C)
         a tax imposed pursuant to Chapter 43 of Subtitle D of the Code;

                  (vi) Each Pension Plan which is intended to be qualified under
         Section  401(a)  of the Code has  received  a  favorable  determination
         letter from the Internal Revenue  Service,  and UniSite is not aware of
         any  circumstances  reasonably  likely to result in the  revocation  or
         denial of any such favorable  determination letter. There is no pending
         or, to its  knowledge,  threatened  litigation or  governmental  audit,
         examination  or  investigation  relating  to any Plan.  Each asset held
         under any Plan may be liquidated or terminated  without the  imposition
         of any redemption fee,  surrender  charge or comparable  liability.  No
         partial  termination  (within the meaning of Section  411(d)(3)  of the
         Code) has occurred with respect to any Pension Plan;

                  (vii)  UniSite has not  maintained  and does not  maintain any
         Pension Plan subject to Title IV of ERISA or any defined benefit Plan;

                  (viii) No Pension Plan has an "accumulated funding deficiency"
         (whether or not  waived)  within the meaning of Section 412 of the Code
         or Section 302 of ERISA. UniSite has not provided,  and is not required
         to  provide,  security to any  Pension  Plan or to any  single-employer
         plan;

                  (ix)  Each  Plan  may be  amended,  terminated,  or  otherwise
         modified by UniSite to the greatest extent permitted by applicable law,
         including the elimination of any and all future benefit  accruals under
         any Plan,  and no  employee  communications  or  provision  of any Plan
         document has failed to  effectively  reserve the right of UniSite to so
         amend, terminate or otherwise modify such Plan;

                  (x) UniSite has not incurred any material  liability to a Plan
         (other than for contributions not yet due) which liability has not been
         fully paid or accrued for payment as of the date  hereof`and  set forth
         in the UniSite Financial Statements;

                  (xi) except as otherwise  set forth in Section  4.11(a) of the
         UniSite Disclosure  Schedule,  no current or former employee of UniSite
         will be entitled to any additional benefits or any acceleration

                                      -14-


<PAGE>



         of the time of payment or  vesting  of any  benefits  under any Plan or
         Benefit  Arrangement as a result of the  transactions  contemplated  by
         this Agreement,  and no such benefit or acceleration will constitute an
         "excess  parachute  payment"  (as  such  term  is  defined  in  Section
         280G(b)(1) of the Code); and

                  (xii)  no  compensation  payable  by  UniSite  to  any  of its
         employees under any existing Plan or Benefit Arrangement  (including by
         reason of the  transactions  contemplated  hereby)  will be  subject to
         disallowance under Section 162(m) of the Code.

         (b)  The  execution,  delivery  and  performance  by  UniSite  of  this
Agreement and the  Collateral  Documents  executed or required to be executed by
UniSite pursuant hereto and thereto will not involve any prohibited  transaction
within  the  meaning of ERISA or  Section  4975 of the Code with  respect to any
Plan.

         4.12 Year 2000  Compliant.  UniSite has  reviewed  the areas within its
business and operations  which UniSite  believes could be adversely  affected by
the "Year 2000 Problem"  (that is, the risk that computer  applications  used by
UniSite may be unable to recognize and perform properly date-sensitive functions
involving  certain  dates prior to and any date on or after  December 31, 1999),
and has made related inquiry of material suppliers, vendors and customers. Based
on such review,  UniSite  believes  that the "Year 2000 Problem" will not have a
material  adverse effect on UniSite.  Except as set forth in Section 4.12 of the
UniSite  Disclosure  Schedule,  each  hardware,  software and  firmware  product
(collectively  "Software")  used  by  UniSite  in  its  business  is  Year  2000
compliant,   except  for  such  noncompliances  that,  individually  or  in  the
aggregate,  have not had and will not have a material adverse effect on UniSite.
The current  status,  projected  cost and  prognosis  of any Year 2000  remedial
efforts  with  respect  to  non-compliant  Software  and  with  respect  to  any
identified Year 2000 issues with any material  supplier,  vendor or customer are
listed in Section 4.12 of the UniSite Disclosure Schedule.

         4.13  Bank  Accounts,  Etc.  Section  4.13  of the  UniSite  Disclosure
Schedule  contains a true,  accurate and complete  list as of the date hereof of
all banks, trust companies, savings and loan associations and brokerage firms in
which  UniSite has an account or a safe deposit box and the names of all Persons
authorized to draw thereon, to have access thereto, or to authorize transactions
therein,  the names of all Persons,  if any, holding valid and subsisting powers
of  attorney  from  UniSite  and a summary  statement  as to the terms  thereof.
UniSite will not make or permit to be made any change  affecting  any account or
safe deposit box with any bank,  trust  company,  savings and loan  association,
brokerage firm or safe deposit box or in the names of the Persons  authorized to
draw thereon, to have access thereto or to authorize  transactions therein or in
such powers of attorney,  or open any additional  accounts or boxes or grant any
additional  powers of  attorney,  without  in each case first  notifying  ATC in
writing.

         4.14  Employment  and  Consulting  Arrangements.  Section  4.14  of the
UniSite Disclosure  Schedule contains a true,  accurate and complete list of all
UniSite employees and consultants (the "UniSite Employees"),  together with each
such  Person's  title or the capacity in which he or she is employed or retained
and each such  Person's  compensation.  UniSite has no  obligation or liability,
contingent or other, under any Employment Arrangement with any UniSite Employee,
other  than (i)  those  listed  or  described  in  Section  4.14 of the  UniSite
Disclosure  Schedule,  (ii) those  incurred in the  ordinary and usual course of
business,  or (iii) such  obligations or liabilities as,  individually or in the
aggregate,  have not had and will not have a material adverse effect on UniSite.
Except as described in Section 4.14 of the UniSite Disclosure Schedule, (a) none
of the UniSite  Employees  is now,  or since  UniSite's  organization  has been,
represented  by  any  labor  union  or  other  employee  collective   bargaining
organization,  and UniSite is not,  and never has been,  a party to any labor or
other  collective  bargaining  agreement  with  respect  to any  of the  UniSite
Employees,  (b) there are no pending grievances,  disputes or controversies with
any union or any other employee or collective bargaining

                                      -15-


<PAGE>



organization  of such  employees,  or  threats of  strikes,  work  stoppages  or
slowdowns or any pending demands for collective  bargaining by any such union or
other organization, (c) neither UniSite nor any of such employees is now, or has
since  its  organization  been,  subject  to or  involved  in or,  to  UniSite's
knowledge,  threatened  with, any union elections,  petitions  therefor or other
organizational  or  recruiting  activities,  in each  case with  respect  to the
UniSite  Employees,  and (d) none of the UniSite  Employees has notified UniSite
that he or she does not intend to  continue  employment  with  UniSite  until or
following  the  Closing.  UniSite has  performed  in all  material  respects all
obligations  required to be performed under all Employment  Arrangements  and is
not in material  breach or violation of or in material  default or arrears under
any of the terms, provisions or conditions thereof.

         4.15  Material  Agreements.  Listed  on  Section  4.15  of the  UniSite
Disclosure  Schedule are all Material Agreements (other than Leases) relating to
the  ownership or operation of the UniSite  Assets or the conduct of the UniSite
Business or to which  UniSite is a party or to which it is bound or which any of
the UniSite  Assets is subject.  True,  accurate and complete  copies of each of
such Material Agreements have been made available by UniSite to ATC, and UniSite
has provided ATC with photocopies of all such Material  Agreements  requested by
ATC (or true, accurate and complete  descriptions thereof have been set forth in
Section  4.15 of the  UniSite  Disclosure  Schedule  with  respect  to  Material
Agreements that are oral).  All of such Material  Agreements are valid,  binding
and legally enforceable obligations of UniSite and, to its knowledge,  all other
parties  thereto,  except as such  enforceability  may be limited by bankruptcy,
moratorium,  insolvency  and similar Laws  affecting  the rights and remedies of
creditors and  obligations  of debtors  generally  and by general  principles of
equity.  Neither  UniSite nor, to its knowledge,  any other party  thereto,  has
failed to duly comply with all of the material terms and conditions of each such
Material Agreement or has done or performed,  or failed to do or perform (and no
Claim is pending or, to the  knowledge of UniSite,  threatened in writing to the
effect that UniSite has not so complied,  done and performed or failed to do and
perform) any act which would  invalidate or provide  grounds for the other party
thereto to terminate  (with or without  notice,  passage of time or both) any of
such  Material  Agreements  or  impair in any  material  respect  the  rights or
benefits  of, or  materially  increase the costs to,  UniSite  under any of such
Material Agreements.

         4.16 Ordinary  Course of Business.  UniSite,  from the date of the most
recent  UniSite  Financial  Statements to the date hereof,  except (i) as may be
described on Section  4.16 of the UniSite  Disclosure  Schedule,  (ii) as may be
required  by the terms of or  described  in this  Agreement,  or (iii) as may be
described in the UniSite Financial Statements:

                  (a) has operated its business in all material  respects in the
         normal,  usual and customary  manner in the ordinary and regular course
         of business, consistent with prior practice;

                  (b) except in each case in the  ordinary  course of  business,
         consistent with prior practice:

                           (i) has not  incurred  any  obligation  or  liability
                  (fixed,  contingent or other)  individually  having a value in
                  excess of $200,000;

                           (ii)  has  not  sold  or  otherwise  disposed  of  or
                  contracted  to  sell  or  otherwise  dispose  of  any  of  its
                  properties or assets having a value in excess of $50,000;

                           (iii) has not entered into any individual  commitment
                  having a value in excess of $50,000; and

                           (iv) has not  canceled  any debts or claims  having a
                  value in excess of $50,000;

                                      -16-


<PAGE>




                  (c) has not created or permitted to be created any Lien on any
         of the UniSite Assets, except for Permitted Liens;

                  (d) has not made or  committed  to make any  additions  to its
         property or any purchases of equipment,  except in the ordinary  course
         of business consistent with past practice or for normal maintenance and
         replacements;

                  (e) has not  increased the  compensation  payable or to become
         payable to any of the UniSite  Employees other than normal  nonmaterial
         increases in the ordinary  course of business to other than officers of
         UniSite, or otherwise materially altered, modified or changed the terms
         of their employment;

                  (f) has not suffered any material damage,  destruction or loss
         (whether or not covered by insurance) or any  acquisition  or taking of
         property by any Authority;

                  (g) has not waived any rights of material  value  without fair
         and adequate consideration;

                  (h) except in the ordinary  course of business not involving a
         labor dispute, has not experienced any work stoppage;

                  (i) except in the ordinary course of business, has not entered
         into,  amended or  terminated  any Lease,  Governmental  Authorization,
         Private Authorization, Material Agreement, Plan, Benefit Arrangement or
         Employment  Arrangement,  or any transaction,  agreement or arrangement
         with any officer, director or Affiliate of UniSite;

                  (j) has not  issued or sold,  or agreed to issue or sell,  any
         shares  of  UniSite  Common  Stock,  other  shares  of  capital  stock,
         Convertible Securities or Option Securities;

                  (k) has not made, paid or declared any Distribution; and

                  (l) has not entered into any transactions or series of related
         transactions  which individually or in the aggregate is material to the
         UniSite Assets or the UniSite Business.

         4.17  Material and Adverse  Restrictions.  UniSite is not a party to or
subject to, nor is any of the UniSite  Assets  subject to, any  Applicable  Law,
Governmental  Authorization,  Contractual  Obligation,  Employment  Arrangement,
Plan, Benefit Arrangement,  Lease, Material Agreement or Private  Authorization,
or any  other  obligation  or  restriction  of any  kind  or  character,  which,
individually or in the aggregate, has had or will have a material adverse effect
on  UniSite,  except  as set forth in  Section  4.17 of the  UniSite  Disclosure
Schedule and except for matters affecting the tower communication sites industry
generally.

         4.18 Broker or Finder. No agent, broker,  investment banker,  financial
advisor  other  firm or Person  engaged by or on behalf of UniSite or any of its
Affiliates or any of the UniSite  stockholders is or will be entitled to any fee
or  commission  in  connection  with  the  transactions   contemplated  by  this
Agreement,  except  Credit  Suisse First Boston  Corporation  ("CSFB") and Fleet
National Bank ("Fleet").

         4.19 Environmental Matters.  Except as set forth in Section 4.19 of the
UniSite Disclosure Schedule, UniSite:

                                      -17-


<PAGE>




                  (a) has not been notified that it is potentially liable under,
         has not received any request for  information  or other  correspondence
         concerning its potential liability with respect to any site or facility
         under, and, to UniSite's knowledge,  is not a "potentially  responsible
         party" under, the Comprehensive  Environmental  Response,  Compensation
         and  Liability  Act of 1980,  as  amended,  the  Resource  Conservation
         Recovery Act, as amended, or any similar state Law;

                  (b) has not  entered  into or  received  any  consent  decree,
         compliance  order  or  administrative  order  issued  pursuant  to  any
         Environmental Law;

                  (c) is  not a  party  in  interest  or in  default  under  any
         judgment,  order,  writ,  injunction or decree  issued  pursuant to any
         Environmental Law;

                  (d) has, to its knowledge,  obtained all Environmental Permits
         required  under  Environmental  Laws,  and has filed all  applications,
         notices and other  documents  required to be filed to effect the timely
         renewal or issuance  of all  Environmental  Permits  for the  continued
         ownership or operation of the UniSite  Assets or conduct of the UniSite
         Business in the manner  currently  owned,  operated  and  conducted  or
         proposed to be owned, operated and conducted prior to the Closing Date;

                  (e)  is in  compliance  in  all  material  respects  with  all
         Environmental  Laws,  and is  not  the  subject  of  or,  to  UniSite's
         knowledge,  threatened  with any Legal  Action  involving  a demand for
         damages or other potential liability,  including any Lien, with respect
         to violations or breaches of any Environmental Law;

                  (f) has not conducted or received any site  assessment,  audit
         or other  investigation  as to  material  environmental  matters at any
         property currently owned, leased, operated or occupied by UniSite;

                  (g)  has  not  manufactured,   processed,  distributed,  used,
         treated,  stored,  installed,  disposed of,  transported or handled any
         Hazardous  Material,  and,  to  UniSite's  knowledge,  none of the real
         property constituting a part of the UniSite Assets has been so used, in
         a manner that, individually or in the aggregate,  has had or could have
         a material adverse effect on UniSite;

                  (h)  is  not  aware  of  any  ambient  air,   surface   water,
         groundwater or land  contamination  or  contamination  within  building
         structures  within,  under,  originating  from or  relating to any real
         property  constituting  a part of the  UniSite  Assets  such  that  the
         contamination impacts any other locations;

                  (i) has not installed or used any above ground or  underground
         storage  tanks,  friable  asbestos,  polychlorinated  biphenyls or urea
         formaldehyde foam insulation on any property currently owned, leased or
         operated by UniSite and, to its knowledge, there are no above ground or
         underground storage tanks, friable asbestos,  polychlorinated biphenyls
         or urea formaldehyde  foam insulation on any property  currently owned,
         leased or operated by UniSite; and

                  (j) has no knowledge of any past or present  Event  related to
         UniSite's properties, operations or business, which Event, individually
         or in the aggregate,  could reasonably be expected to interfere with or
         prevent  continued   compliance  in  all  material  respects  with  all
         Environmental  Laws  applicable  to the  ownership  or operation of the
         UniSite Assets or to the conduct of the UniSite

                                      -18-


<PAGE>



         Business  substantially  in the manner now  conducted or proposed to be
         conducted on or prior to the Closing Date, or which, individually or in
         the aggregate,  may form the basis of any material Claim for or arising
         out of the release or threatened  release into the  environment  of any
         Hazardous Material.

Section 4.19 of the UniSite  Disclosure  Schedule sets forth a true, correct and
complete list of all existing Phase I environmental  site assessment reports (an
"Environmental  Report")  on each  parcel  of real  property  owned or leased by
UniSite for which an  Environmental  Report has  previously  been  prepared  for
UniSite  (true,  correct  and  complete  copies of which  have  heretofore  been
delivered by UniSite to ATC).

         4.20 Capital Stock.  The authorized  and  outstanding  capital stock of
UniSite is as set forth in Section 4.20 of the UniSite Disclosure Schedule.  All
of such  outstanding  capital stock has been duly authorized and validly issued,
is fully paid and  nonassessable and is not subject to any preemptive or similar
rights and is owned of record and, to UniSite's knowledge, beneficially as shown
in  Section  4.20 of the  UniSite  Disclosure  Schedule.  Except as set forth in
Section  4.20 of the  UniSite  Disclosure  Schedule,  UniSite has not granted or
issued,  nor has  UniSite  agreed to grant or issue,  any shares of its  capital
stock or any Option Security or Convertible Security, and UniSite is not a party
to or  bound  by any  agreement,  put or  commitment  pursuant  to  which  it is
obligated to purchase,  redeem or otherwise  acquire any shares of capital stock
or any Option Security or Convertible Security.


                                    ARTICLE 5

                  REPRESENTATIONS AND WARRANTIES OF ATC AND ATI

         Each of ATC and ATI,  jointly  and  severally,  hereby  represents  and
warrants to UniSite and the UniSite stockholders as follows:

         5.1  Organization  and  Business;   Power  and  Authority;   Effect  of
Transaction.

         (a)  Each of ATC  and  ATI is a  corporation  duly  organized,  validly
existing  and in good  standing  under  the DCL,  has all  requisite  power  and
authority (corporate and other) to own or hold under lease its properties and to
conduct its business as now conducted and is duly qualified and in good standing
as a foreign  corporation in each other  jurisdiction  in which the character of
the property  owned or leased by it or the nature of its business or  operations
requires such qualification, except for such qualifications the failure of which
to obtain,  individually  or in the aggregate,  have not had and will not have a
material adverse effect on ATC.

         (b)  Each  of ATC  and  ATI  has  all  requisite  power  and  authority
(corporate  and  other)  and has in  full  force  and  effect  all  Governmental
Authorizations and Private Authorizations  necessary to enable it to execute and
deliver,  and  to  perform  its  obligations  under,  this  Agreement  and  each
Collateral Document executed or required to be executed by it pursuant hereto or
thereto and to consummate  the  Transactions;  and the  execution,  delivery and
performance  by ATC and ATI of  this  Agreement  and  each  Collateral  Document
executed or required to be executed by it pursuant  hereto or thereto  have been
duly  authorized by all  requisite  corporate or other action on the part of ATC
and ATI. This  Agreement has been duly executed and delivered by ATC and ATI and
constitutes, and each Collateral Document executed or required to be executed by
each of them pursuant hereto or thereto or to consummate the  Transactions  when
executed and delivered by ATC and ATI will constitute,  legal, valid and binding
obligations  of  each of ATC and  ATI,  enforceable  in  accordance  with  their
respective terms, except as such enforceability may be limited by bankruptcy,

                                      -19-


<PAGE>



moratorium,  insolvency  and similar Laws  affecting  the rights and remedies of
creditors and  obligations  of debtors  generally  and by general  principles of
equity.

         (c) Except to the  extent  necessary  under  their  credit  facilities,
neither  the  execution  and  delivery by ATC and ATI of this  Agreement  or any
Collateral Document executed or required to be executed by each of them pursuant
hereto or thereto, nor the consummation of the Transactions, nor compliance with
the terms, conditions and provisions hereof or thereof by ATC and ATI:

                  (i) will conflict with, or result in a breach or violation of,
         or constitute a default  under,  any Organic  Document of ATC or ATI or
         any  Applicable  Law, or will  conflict  with, or result in a breach or
         violation of, or constitute a default under, or permit the acceleration
         of any obligation or liability in, or but for any requirement of giving
         of notice or passage of time or both would  constitute  such a conflict
         with,  breach or  violation  of, or default  under,  or permit any such
         acceleration in, any Contractual Obligation of ATC or ATI; or

                  (ii)  will   require   ATC  or  ATI  to  make  or  obtain  any
         Governmental    Authorization,    Governmental    Filing   or   Private
         Authorization,  except (A)  filings  contemplated  by the  Registration
         Rights Agreement,  (B) filings under the Hart-Scott-Rodino Act, (C) for
         Federal  Aviation   Administration   and  the  Federal   Communications
         Commission approvals, (D) the filing with the SEC of such reports under
         Section  13(a) or  15(d)  of the  Exchange  Act as may be  required  in
         connection  with  this  Agreement  and  the  transactions  contemplated
         hereby,  (E) the filing of the  Certificate of Merger with the Delaware
         Secretary  of  State,  and  appropriate  documents  with  the  relevant
         authorities  of other  states in which ATI is qualified to do business,
         and (F) such other Governmental  Authorizations,  Governmental Filings,
         and Private  Authorizations the failure of which to be made or obtained
         would not,  individually or in the aggregate,  have a material  adverse
         effect on ATC.

         5.2 ATC SEC  Reports.  ATC has  heretofore  made  available to UniSite,
including for furnishing to the UniSite  stockholders,  (a) its Annual Report on
Form 10-K for the fiscal year ended December 31, 1998, (b) its prospectus, dated
February 3, 1999,  (c) its Quarterly  Report on Form 10-Q for the fiscal quarter
ended  March 31,  1999,  and (d) all  Current  Reports  on Form 8-K filed  since
February 3, 1999 (collectively,  the "ATC SEC Documents").  As of the respective
dates thereof,  the ATC SEC Documents were prepared in all material  respects in
accordance  with the Securities Act or the Exchange Act, as applicable,  and did
not  contain  any  untrue  statement  of a  material  fact or omit to state  any
material fact required to be stated  therein or necessary to make the statements
therein,  in  light  of the  circumstances  under  which  they  were  made,  not
misleading.  ATC has timely filed all forms,  reports and documents with the SEC
required to be filed by it pursuant to the  Securities  Act and the Exchange Act
which complied as to form, at the time such form,  document or report was filed,
in all material respects with the applicable  requirements of the Securities Act
and the Exchange Act. The consolidated  financial  statements of ATC included in
the ATC SEC Documents (the "ATC Financial  Statements"),  including in each case
the notes  thereto,  have been  prepared in  accordance  with GAAP  applied on a
consistent  basis  throughout the periods covered  thereby,  except as otherwise
noted therein,  and fairly present the consolidated  financial condition and the
consolidated  results of  operations  and cash flow of ATC, on the bases therein
stated,  as of the  respective  dates thereof,  and for the  respective  periods
covered  thereby  subject,  in the case of unaudited  financial  statements,  to
normal nonmaterial year-end audit adjustments and accruals.

         5.3 Material Statements and Omissions;  Absence of Events.  Neither any
representation  or warranty made by ATC or ATI contained in this Agreement or in
any certificate,  document or other  instrument  furnished or to be furnished by
ATC or ATI pursuant to the provisions hereof nor the ATC SEC Documents

                                      -20-


<PAGE>



contains or will  contain any untrue  statement  of a material  fact or omits or
will omit to state any material fact  required to make any  statement  contained
herein or therein, in light of the circumstances under which they were made, not
misleading.  Since the date of the most recent financial statements constituting
a part of the ATC Financial Statements there has been no change with respect to,
and there is no Event known to, ATC that has had or will have a material adverse
effect  on  ATC,  except  (a) to the  extent  set  forth  in any of the  ATC SEC
Documents,  (b) for matters  affecting the industry  generally,  and (c) for any
Event arising out of the execution or public announcement of this Agreement. ATC
is not aware of any impending or contemplated  Event that would cause any of the
representations  and  warranties  made by it in  this  Article  not to be  true,
correct and complete on the date of such Event as if made on that date.

         5.4 Broker or Finder. No agent,  broker,  investment banker,  financial
advisor,  other  firm or  Person  engaged  by or on  behalf of ATC or any of its
Affiliates is or will be entitled to any fee or  commission  in connection  with
the transactions contemplated by this Agreement.

         5.5 Legal  Actions.  There are no Legal Actions of any kind pending or,
to the  knowledge of ATC,  threatened  at Law, in equity or before any Authority
against ATC or any of its Subsidiaries or any of its or any of their officers or
directors  relating to the ownership or operation of their assets and properties
or the  conduct  of their  businesses  that,  if  determined  adversely  to ATC,
individually  or in the aggregate,  would have a material  adverse effect on ATC
and its Subsidiaries taken as a whole.

         5.6  Absence  of  Change  of  Control.   ATC  is  not  engaged  in  any
negotiations or discussions that, individually or in the aggregate, could result
in a Change of Control of ATC.

         5.7  Adequate  Financial  Resources.  ATC has  available to it adequate
financial  resources to consummate the Merger,  including without limitation the
ability to make payment of the Cash Consideration.


                                    ARTICLE 6

                                    COVENANTS

         6.1      Access to Information; Confidentiality.

         (a) Each party  shall  afford to the other  party and its  accountants,
counsel,  financial advisors and other  representatives (the  "Representatives")
full access  during normal  business  hours  throughout  the period prior to the
Closing Date to all of its (and its Subsidiaries') properties, books, contracts,
insurance  policies,  studies and  reports,  environmental  studies and reports,
commitments and records  (including  without limitation Tax Returns) and, during
such period,  shall  furnish  promptly  upon written  request (i) a copy of each
report,  schedule and other  document filed or received by any party pursuant to
the  requirements  of any  Applicable  Law or filed by it with any  Authority in
connection with the Merger or any other report,  schedule or documents which may
have a material effect on the  businesses,  operations,  properties,  prospects,
personnel,  condition  (financial  or other),  or results of operations of their
respective  businesses,  (ii) to the extent not  provided  for  pursuant  to the
immediately  preceding  clause, in the case of UniSite,  all financial  records,
ledgers,  work papers and other  sources of financial  information  possessed or
controlled by it or any of its  Subsidiaries or its or any of their  accountants
deemed by ATC or its  Representatives  necessary  or useful  for the  purpose of
performing an audit of the business and assets of UniSite,  and (iii) such other
information  concerning any of the foregoing as ATC or UniSite shall  reasonably
request.  All Confidential  Information  furnished pursuant to the provisions of
this  Agreement,  including  without  limitation  this  Section,  will  be  kept
confidential and shall not, without

                                      -21-


<PAGE>



the prior written consent of the party disclosing such Confidential Information,
be disclosed by the other party in any manner  whatsoever,  in whole or in part,
and,  except as required by  Applicable  Law  (including  without  limitation in
connection  with any  registration,  proxy or  information  statement or similar
document  filed  pursuant to any federal or state  securities  Law) shall not be
used for any  purposes,  other than in  connection  with the  Merger.  Except as
otherwise  herein  provided,  each  party  agrees  to reveal  such  Confidential
Information  only to  those of its  Representatives  or  other  Persons  whom it
believes  need  to  know  such  Confidential  Information  for  the  purpose  of
evaluating  and  consummating  the  Merger.  For  purposes  of  this  Agreement,
"Confidential  Information"  shall mean any and all  information  related to the
business or  businesses of ATC, ATI and their  respective  Affiliates or UniSite
and its Affiliates,  including any of their  respective  successors and assigns,
other  than  information  that  (i)  has  been  or is  obtained  from  a  source
independent of the disclosing party that, to the receiving party's knowledge, is
not subject to any  confidentiality  restriction,  (ii) is or becomes  generally
available to the public other than as a result of unauthorized disclosure by the
receiving  party,  or (iii) is  independently  developed by the receiving  party
without  reliance in any way on information  provided by the disclosing party or
by a third party  independent  of the  disclosing  party that,  to the receiving
party's knowledge, is not subject to any confidentiality restriction.

         (b)  Notwithstanding  the provisions of Section 6.1(a),  (i) each party
may disclose such information as it may reasonably  determine to be necessary in
connection with seeking all Governmental and Private  Authorizations  or that is
required by Applicable Law to be disclosed,  including without limitation in any
registration,  proxy or information  statement or other document  required to be
filed  under any federal or state  securities  Law,  and (ii) ATC may,  with the
prior  written  consent of  UniSite,  which  consent  shall not be  unreasonably
withheld, delayed or conditioned,  disclose the subject matter of this Agreement
to Persons  with whom  UniSite  or any of its  Subsidiaries  has a  business  or
contractual relationship in connection with ATC's due diligence investigation of
UniSite and its Subsidiaries.  In the event that this Agreement is terminated in
accordance  with its terms,  each party  shall  promptly  redeliver  all written
Confidential  Information  provided  pursuant  to  this  Section  or  any  other
provision of this Agreement or otherwise in connection with the Merger and shall
not retain any copies,  extracts or other  reproductions  in whole or in part of
such written  material,  other than one copy thereof which shall be delivered to
independent counsel for such party.

         (c)  Anything in this  Section or  elsewhere  in this  Agreement to the
contrary  notwithstanding,  either  party may disclose  information  received or
retained by it in accordance  with the  provisions  of this  Agreement if it can
demonstrate  (i) such  information  is  generally  available  to or known by the
public from a source other than the party seeking to disclose  such  information
or (ii) was obtained by the party  seeking to disclose such  information  from a
source  other than the other  party,  provided  that such source was not, to the
knowledge of the disclosing  party,  bound by a duty of  confidentiality  to the
other party or another party with respect to such information.

         (d) No investigation pursuant to this Section or otherwise shall affect
any  representation  or warranty in this Agreement of any party or any condition
to the obligations of the parties hereto.

         6.2 Agreement to Cooperate; Certain Other Covenants.

         (a) Each of the parties  hereto shall use reasonable  business  efforts
(x) to take,  or cause to be taken,  all actions and to do, or cause to be done,
all things necessary, proper or advisable under Applicable Law to consummate the
Merger and the other  Transactions,  and (y) to refrain from taking, or cause to
refrain from taking, any action and to refrain from doing or causing to be done,
anything  which  could  impede or impair the  consummation  of the Merger or the
consummation  of  the  other  Transactions,  including,  in all  cases,  without
limitation  using its reasonable  business  efforts (i) to prepare and file with
the applicable Authorities as

                                      -22-


<PAGE>



promptly as  practicable  after the  execution of this  Agreement  all requisite
applications and amendments thereto, together with related information, data and
exhibits,  necessary to request  issuance of orders  approving the Merger by all
such  applicable  Authorities,  (ii) to  obtain  all  necessary  or  appropriate
waivers,  consents and approvals,  (iii) to effect all necessary  registrations,
filings and submissions (including without limitation (A) filings within fifteen
(15) business  days of the date of this  Agreement  under the  Hart-Scott-Rodino
Act, and (B) all filings necessary for ATI to own and operate the UniSite Assets
and the UniSite Business,  (iv) to lift any injunction or other legal bar to the
Merger  (and,  in such case,  to proceed  with the  Merger as  expeditiously  as
possible),  and (v) to obtain the  satisfaction  of the conditions  specified in
Article 7, and (vi) to advise the other of, in the case of UniSite,  any changes
that would be  required  in the UniSite  Disclosure  Schedule if the  applicable
representations  and warranties set forth in Article 4 did not refer to the date
of  this  Agreement.   The  provisions  of  this  Section  shall  apply  to  all
Subsidiaries of ATC and UniSite.

         (b) The parties shall  cooperate with one another in the preparation of
all Tax Returns,  questionnaires,  applications or other documents regarding any
Taxes or transfer, recording, registration or other fees which become payable in
connection  with the  Merger  that are  required  to be filed on or  before  the
Closing Date.

         (c) UniSite shall cooperate and use its reasonable  business efforts to
cause its independent  accountants to reasonably  cooperate with ATC in order to
enable  ATC,  at its  sole  discretion  and  expense,  to have  its  independent
accountants  prepare the audited  financial  statements for UniSite described in
Section 7.2(g).  UniSite will use its reasonable business efforts to ensure that
such  financial  statements  will have been  prepared  in  accordance  with GAAP
applied on a basis  consistent  with the UniSite  Financial  Statements and will
present  fairly the financial  condition,  results of operation and cash flow of
UniSite.  Without limiting the generality of the foregoing,  UniSite agrees that
it will (i)  consent  to the use of such  audited  financial  statements  in any
registration,  proxy or information  statement or other document filed by ATC or
any of its  Affiliates  under the  Securities  Act or the  Exchange Act and (ii)
execute  and  deliver,  and cause its  officers  to execute  and  deliver,  such
"representation"  letters as are customarily delivered in connection with audits
and  as  ATC's  independent   accountants  may  reasonably   request  under  the
circumstances.

         6.3 Public Announcements.  Until the Closing or the termination of this
Agreement,  each party shall  consult  with the other  before  issuing any press
release or otherwise making any public statements with respect to this Agreement
or the Merger and shall not issue any such press release or make any such public
statement without the prior written approval of the other.  Notwithstanding  the
foregoing, the parties acknowledge and agree that they may, without each other's
prior consent,  issue such press releases or make such public  statements as may
be required  by  Applicable  Law, in which case the issuing  party shall use all
reasonable  efforts to consult  with the other  party and agree upon the nature,
content and form of such press release or public statement.

         6.4  Notification  of Certain  Matters.  Each party  shall give  prompt
notice  to the  other of the  occurrence  or  non-occurrence  of any  Event  the
occurrence or  non-occurrence  of which would be reasonably  likely to cause (a)
any  representation  or warranty  made by it contained  in this  Agreement to be
untrue or inaccurate in any material  respect or (b) any failure by it to comply
with or satisfy,  or be able to comply with or satisfy, in any material respect,
any  covenant,  condition or  agreement  to be complied  with or satisfied by it
under this Agreement in any material  respect,  such that, in any such case, one
or more of the conditions of Closing would not be satisfied;  provided, however,
that the  delivery  of any notice  pursuant to this  Section  shall not limit or
otherwise  affect the  rights  and  remedies  available  hereunder  to the party
receiving such notice or the obligations of the party delivering such notice and
shall not, in any event, affect the representations,

                                      -23-


<PAGE>



warranties,  covenants and  agreements of the parties or the conditions to their
respective obligations under this Agreement.

         6.5 Other Offers; No Solicitation.

         (a) UniSite agrees that it and its Subsidiaries,  officers,  employees,
agents and representatives (including without limitation any investment bankers,
brokers,  financial advisors,  finders, attorneys or accountants) (i) shall not,
directly  or  indirectly,  after the date  hereof,  (A)  initiate or solicit any
inquiries or the making of any proposal or offer with respect to an  Alternative
Transaction  or that  constitutes,  or may reasonably be expected to lead to, an
Alternative  Transaction,  or (B) engage or participate in any  negotiations  or
otherwise  cooperate  or  provide  assistance  (including  by way of  furnishing
non-public  information)  relating  to or  in  contemplation  of an  Alternative
Transaction,  (ii) have terminated any discussions or negotiations with, and the
provisions of information or data (whether or not of a non-public nature) to any
Person relating to or in contemplation of an Alternative Transaction,  and (iii)
have, or within two (2) days of the date of this Agreement will have,  requested
each  Person  that  has  heretofore  executed  a  confidentiality  agreement  in
connection with its  consideration  of an Alternative  Transaction to return all
confidential  information heretofore furnished to such Person by or on behalf of
it or any of its Subsidiaries  and will not waive any "standstill"  provision of
any such, or any other agreement.

         (b) Nothing  contained in this Agreement  shall,  except as hereinafter
provided in this Section 6.5(b),  prevent UniSite or its Board of Directors from
at any time prior to the UniSite Stockholder Approval, if the Board of Directors
of UniSite  determines in good faith,  after the advice of and consultation with
legal counsel, that a written Alternative Transaction (A) would, if consummated,
constitute a Superior Proposal,  and (B) that (and only to the extent that) such
action is  necessary in order for the  directors to comply with their  fiduciary
duties to UniSite's  stockholders  under Applicable Law, UniSite may (x) furnish
non-public  information  with  respect  to  UniSite  to the Person who made such
Alternative  Transaction pursuant to a customary  confidentiality  agreement and
(y)  participate  in discussions  and  negotiations  regarding such  Alternative
Transaction,  but only if (A) UniSite has not breached and is not then in breach
of its obligations under this Section,  and (B) confidentiality  arrangements on
terms no less  favorable  to  UniSite as those set forth in this  Agreement  are
entered into with respect thereto;  provided,  however, that neither UniSite nor
its Board of Directors shall, except as permitted by Section 6.5(c),  propose to
approve or recommend an Alternative Transaction.

         (c) The Board of Directors of UniSite shall not (i) withdraw or modify,
or propose to withdraw or modify,  in a manner  adverse to ATC,  its approval or
recommendation  of this Agreement or the Merger,  (ii) approve or recommend,  or
propose to approve or  recommend,  an  Alternative  Transaction,  or (iii) cause
UniSite to enter into any letter of intent, agreement in principle,  acquisition
agreement or merger or other similar  agreement  with respect to an  Alternative
Transaction,  unless (x) the UniSite Stockholder Approval has not been obtained,
(y) Board of Directors of UniSite shall have determined in good faith, after the
advice  of  and  consultation  with  legal  counsel  and  UniSite's  independent
financial advisors, that (A) such action is necessary in order for the directors
to comply with their fiduciary duties to UniSite's stockholders under Applicable
Law,  and (B) such  Alternative  Transaction  is a  Superior  Proposal,  and (z)
UniSite  shall be  permitted  to  terminate,  and shall  have  terminated,  this
Agreement pursuant to the provisions of paragraph (f) of Section 8.1.

         (d) UniSite  shall  promptly  (but in any event  within three (3) days)
advise ATC orally and in writing of any  Alternative  Transaction or any inquiry
relating to or  contemplating an Alternative  Transaction  including any request
for information,  the material terms and conditions of such request, Alternative
Transaction  or inquiry  and the  identity of the person  making  such  request,
Alternative Transaction or inquiry.

                                      -24-


<PAGE>



UniSite will, to the extent reasonably  practicable,  keep ATC fully informed of
the status and details (including amendments or proposed amendments) of any such
request, Alternative Transaction or inquiry. ATC shall have the right, but shall
not be obligated, within five (5) days after such notification (including of any
material amendment or proposed amendment), to revise its offer to consummate the
Merger and to  communicate  such  revised  offer in writing to UniSite.  UniSite
shall be obligated to consider any such  revised  offer in  connection  with its
consideration of an Alternative Transaction.

         (e) If,  prior  to the  UniSite  Stockholder  Approval,  UniSite  shall
receive a firm, bona fide written proposal or proposals from any Person relating
to an Alternative Transaction,  and UniSite's Board of Directors shall determine
in good  faith,  after the advice of and  consultation  with legal  counsel  and
UniSite's independent financial advisors,  that such Alternative Transaction (i)
would, if consummated, constitute a Superior Proposal, and (ii) that termination
of this Agreement and acceptance of such Alternative Transaction is necessary in
order for the  directors  to comply  with their  fiduciary  duties to  UniSite's
stockholders  under Applicable Law, then UniSite shall, upon compliance with the
provisions  of  Section  6.5(f) and if it has not  breached,  and is not then in
breach of, this Section,  terminate this Agreement pursuant to the provisions of
Section 8.1(f).

         6.6 Conduct of Business  by UniSite  Pending the Merger.  Except as set
forth  in  Section  6.6 of  the  UniSite  Disclosure  Schedule  or as  otherwise
contemplated by this  Agreement,  after the date hereof and prior to the Closing
Date or  earlier  termination  of this  Agreement,  unless  ATC shall  otherwise
consent in writing,  UniSite shall, and, if applicable,  shall cause each of its
Subsidiaries to:

                  (a) conduct its  business in the  ordinary and usual course of
         business and consistent with past practice;

                  (b) not (i) amend or propose to amend its  Organic  Documents,
         (ii)  split,  combine  or  reclassify  (whether  by stock  dividend  or
         otherwise)  its  outstanding  capital  stock or issue or authorize  the
         issue  of any  other  securities  in  respect  of,  in lieu  of,  or in
         substitution  for, shares of its capital stock,  or (iii) declare,  set
         aside,  pay or make, or agree to declare,  set aside,  pay or make, any
         Distribution, whether in cash, stock, property or otherwise;

                  (c) not issue,  sell, pledge or dispose of, or agree to issue,
         sell,  pledge or dispose of, any shares of UniSite Common Stock,  other
         shares of capital stock,  Convertible  Securities or Option Securities,
         except pursuant to the conversion of outstanding Convertible Securities
         or the exercise of outstanding Option Securities;

                  (d) not (i) incur or become  contingently  liable with respect
         to any  Indebtedness  for Money Borrowed,  other than  Indebtedness for
         Money Borrowed (A) outstanding as of the date of this Agreement and (B)
         owed to ATC or one of its  Subsidiaries  pursuant to the UniSite Notes,
         (ii) redeem, purchase, acquire or offer or agree to redeem, purchase or
         acquire  any shares of its capital  stock,  Convertible  Securities  or
         Option Securities,  (iii) sell, lease, license,  pledge,  dispose of or
         encumber any properties or assets or sell any businesses other than (x)
         non material assets in the ordinary  course of business,  (y) Permitted
         Liens or other  Liens  arising in  accordance  with the  provisions  of
         Indebtedness  for Money  Borrowed  in effect on the date  hereof and in
         accordance with its present terms, and (z) leases of towers and shelter
         space to third-party  customers,  or (iv) except in connection with the
         Omnipoint   Acquisition,   make  any   loans,   advances   or   capital
         contributions  to,  or  investments  in,  any other  Person,  except to
         officers and employees for travel,  business or relocation  expenses in
         the ordinary course of business;


                                      -25-


<PAGE>



                  (e) not  enter  into or  agree to  enter  into any  Restricted
         Transaction (or group of related Restricted Transactions),  whether for
         its  own  account  or  for  any  other  Person,   other  than  (i)  the
         construction  of towers (x) pursuant to the  Omnipoint  Agreement,  the
         AT&T  Agreement or other BTS  Agreements  that have  received the prior
         written approval of ATC, such approval not to be unreasonably withheld,
         delayed or  conditioned,  or (y) if such towers  meet the  Construction
         Guidelines  or have  otherwise  been  approved in writing by ATC,  such
         approval not to be unreasonably withheld, delayed or conditioned,  (ii)
         the  acquisition  of   communication   sites  and  towers  and  related
         businesses, if such acquisition has received the prior written approval
         of ATC,  such  approval  not to be  unreasonably  withheld,  delayed or
         conditioned,  except that it shall be  conditioned  upon the receipt of
         Environmental  Reports  with  respect to all such sites,  and (iii) the
         Omnipoint Acquisition;

                  (f) use  reasonable  business  efforts to preserve  intact its
         business organization and goodwill,  keep available the services of its
         present  officers  and key  employees,  and  preserve  the goodwill and
         business  relationships  with  customers  and  others  having  business
         relationships  with them and not  engage  in any  action,  directly  or
         indirectly,  with the  intent  to  adversely  impact  the  transactions
         contemplated by this Agreement;

                  (g) confer on a regular  and  frequent  basis with one or more
         representatives of ATC to report material  operational  matters and the
         general status of ongoing operations;

                  (h) not adopt,  enter into, amend or terminate any employment,
         severance,  special pay  arrangement  with  respect to  termination  of
         employment  or  other  similar  arrangements  or  agreements  with  any
         directors,  officers or key employees,  except as  contemplated  by the
         terms of this Agreement;

                  (i) maintain with financially  responsible insurance companies
         insurance  on the  UniSite  Assets  and the  UniSite  Business  in such
         amounts and against such risks and losses as are  consistent  with past
         practice;

                  (j) not make any Tax election that could  reasonably be likely
         to have a material  adverse  effect on UniSite or settle or  compromise
         any material Tax liability;

                  (k) cause Environmental Reports to be prepared with respect to
         all  communication  sites upon which  Completed  Towers or towers under
         construction at the Effective Time are located, except Completed Towers
         that are (i)  described  in Section  4.4(a) of the  UniSite  Disclosure
         Schedule,  or (ii)  that are  acquired  subsequent  to the date of this
         Agreement, subject, however, to the provisions of Section 6.6(e);

                  (l) except in the  ordinary  course of business or pursuant to
         the Omnipoint Amendment, or except as would not be reasonably likely to
         have,  individually or in the aggregate,  a material  adverse effect on
         UniSite,  not modify,  amend or terminate any agreement  referred to in
         the definition of Required Consents or any other Material  Agreement to
         which UniSite or any of its  Subsidiaries is a party or by which any of
         the UniSite  Assets may be bound or to which any of them may be subject
         or waive, release or assign any material rights or claims thereunder;

                  (m) not make any material  change to its  accounting  methods,
         principles or practices, except as may be required by GAAP;


                                      -26-


<PAGE>



                  (n)  except  in  the  ordinary   course  of  business  and  in
         accordance with past procedures and policies,  not enter into any Lease
         or other  agreement  with  respect to any  antennae  site on any of its
         towers, whether presently owned or hereafter acquired by UniSite or any
         of its Subsidiaries;

                  (o)  except  as set  forth  in  Section  4.14  of the  UniSite
         Disclosure Schedules or the letter referred to in Section 6.14, (i) not
         grant to any executive  officer or other key employee of UniSite or any
         of its  Subsidiaries  any increase in  compensation,  except for normal
         increases  in the  ordinary  course of  business  consistent  with past
         practice or as required under Benefit Arrangements set forth in Section
         4.14 of the  UniSite  Disclosure  Schedule,  (ii) not grant to any such
         executive  officer any increase in severance or termination pay, except
         as was  required  under any Benefit  Arrangements  set forth in Section
         4.14 of the UniSite Disclosure  Schedule,  (iii) not adopt or amend any
         Plan or Benefit  Arrangement  (including  change any actuarial or other
         assumption used to calculate  funding  obligations  with respect to any
         Plan, or change the manner in which  contributions to any Plan are made
         or the  basis on which  such  contributions  are  determined)  and (iv)
         except in the ordinary  course,  not enter into,  amend in any material
         respect or terminate any Governmental  Authorization,  material Private
         Authorization or Contract;

                  (p) not  voluntarily  take or permit  to be taken  any  action
         which if taken  between the end of its most recent  fiscal  quarter and
         prior to the date of this  Agreement  would  have been  required  to be
         noted  as an  exception  on  Section  4.16  of the  UniSite  Disclosure
         Schedule,  other than  pursuant to the  conduct of its  business in the
         ordinary  and  usual  course  of  business  and  consistent  with  past
         practice; and

                  (q) not  authorize  or enter  into any  agreement  that  would
         violate any of the foregoing.

In the event that UniSite or any of its Subsidiaries  desires to take any of the
actions  prohibited  by the  provisions  of this  Section,  it shall give prompt
written notice to ATC, referring to the provisions of this Section. In the event
that ATC does not object to the taking of such action  within ten (10)  business
days of receipt of such notice and all  material  information  requested  by ATC
with respect thereto, UniSite or any of its Subsidiaries shall have the right to
take such action. ATC's failure to object to the taking of any such action shall
not,  in any event,  relieve  UniSite  from the  obligation  to comply  with the
provisions  of this  Agreement  and  shall  not be  deemed to be a waiver of any
condition of ATC's  obligations  to  consummate  the Merger set forth in Section
6.2.  Anything in this Section or  elsewhere  in this  Agreement to the contrary
notwithstanding,  UniSite shall not amend,  modify or  terminate,  or permit the
termination of, the GTE Management Agreement or the Omnipoint Agreement, without
the express prior written approval of ATC, in its sole and absolute discretion.

         6.7  Preliminary  Title Reports.  As promptly as practicable  after the
execution of this Agreement,  UniSite shall, at its cost and expense, deliver or
cause to be  delivered  to ATC a standard  preliminary  title report (the "Title
Report")  dated  within  one  hundred  and fifty  (150) days of the date of this
Agreement  issued by a nationally  recognized  title  company or companies  with
respect  to each  parcel of real  property  owned or leased  by  UniSite  or, if
applicable, any of its Subsidiaries.

         6.8 Environmental  Site  Assessments.  As promptly as practicable after
the execution of this Agreement, ATC may, but shall not be obligated, at its own
cost and expense  obtain,  and deliver to UniSite full and  complete  copies of,
Environmental  Reports on any or all of those  certain  parcels of real property
owned or leased by UniSite on which any tower presently exists.  ATC understands
that UniSite will,  pursuant to the provisions of Section 6.6(k),  be obtaining,
and UniSite agrees to deliver to ATC full and complete copies

                                      -27-


<PAGE>



of,  Environmental  Reports.  Except to the extent  that  UniSite  is  obligated
pursuant to site acquisition agreements or commitments presently in effect, site
assessments for both such categories of Environmental Reports shall be conducted
by such  consultants and  professionals  as ATC and UniSite shall mutually agree
and shall be arranged at times mutually convenient to the parties. To the extent
reasonably  feasible,  each  of  UniSite  and  ATC  shall  be  entitled  to have
representatives present at the time such site assessments are conducted,  and to
have  copies  of  all  correspondence  with  the  Persons  conducting  the  site
assessments and preparing the Environmental Reports. ATC shall:

                  (a) prior to the later to occur of (i) the  expiration  of the
         due diligence  period  referred to in Section 10.16,  and (ii) five (5)
         business days of the delivery of an Environmental Report required to be
         obtained  by UniSite  pursuant  to the  provisions  of Section  6.6(k),
         advise UniSite in writing as to any objections to the matters  revealed
         in such  Environmental  Report; to the extent that ATC has failed to so
         advise  UniSite,  ATC shall be deemed to have waived the  condition set
         forth in Section 7.2(f); and

                  (b)  prior  to the  expiration  of the  due  diligence  period
         referred  to in  Section  10.16,  advise  UniSite  in writing as to any
         objections to the matters revealed in any Environmental  Report ordered
         by it pursuant to the  provisions of this  Section;  to the extent that
         ATC has failed to (i) order an Environmental Report with respect to any
         site presently owned by UniSite on which there is a Completed Tower, or
         (ii) so advised  UniSite as to any  objections,  ATC shall be deemed to
         have waived the condition set forth in Section 7.2(f).

         6.9 Interim Financing for UniSite; ATC Commitment.

         (a) ATC  agrees to  provide  interim  debt  financing  to UniSite in an
aggregate  principal amount not to exceed $50.0 million (or with the approval of
ATC, such approval not to be unreasonably withheld, delayed or conditioned,  not
to exceed $60.0  million) as from time to time  requested by UniSite on not less
than three (3) business days notice to ATC. Any such financing shall be advanced
against a secured note  substantially  in the form attached  hereto as Exhibit B
and made a part hereof (the "UniSite  Notes") and shall be secured by a security
agreement substantially in the form attached hereto as Exhibit C and made a part
hereof (the "UniSite Security Agreement"). UniSite shall use the proceeds of the
sale of the  UniSite  Notes to ATC  hereunder  solely (i) to repay the  existing
Indebtedness for Money Borrowed to banks and other financial institutions,  (ii)
to complete the development of new communication sites and capital  improvements
to its existing  communication  sites,  (iii) to finance the  acquisition of new
communication  sites and related  assets that have been approved by ATC pursuant
to, or are  permitted  by, the  provisions  of  Section  6.6,  (iv) to  guaranty
UniSite's  performance of the Omnipoint  Agreement and any agreement referred to
in the plan  contemplated  by Section 6.14, and (v) for other general  corporate
purposes.  The parties  acknowledge that,  simultaneously with the execution and
delivery of this  Agreement,  (x) UniSite has executed and delivered the UniSite
Note to ATC,  (y) UniSite  and ATC have  executed  and  delivered  the  Security
Agreement, and (z) ATC has advanced funds to repay the existing Indebtedness for
Money Borrowed to banks and other financial institutions, plus $10.0 million for
the  purpose  described  in  clause  (iii) and $15.0  million  for the  purposes
described in clauses (ii) and (v) of this Section.

         (b) ATC agrees,  at the written  request of UniSite,  and following the
expiration or earlier termination of the Hart-Scott-Rodino Act filing period, to
complete or cause to be completed  one or more towers  pursuant to the Omnipoint
Agreement,  in which event any such towers  shall not be deemed to be  Completed
Towers and shall be owned by ATC or one of its Subsidiaries.


                                      -28-


<PAGE>



         6.10  Solicitation  of Employees.  Each of ATC and UniSite  agrees that
neither it nor any of its  Affiliates  will,  for a period of twelve (12) months
from the date this Agreement is terminated, solicit or actively seek to hire any
individual who during such period is employed by ATC or any of its Affiliates or
UniSite  or any of its  Affiliates,  as the  case  may be,  whether  or not such
individual  would commit  breach of such  individual's  employment  agreement or
contract in leaving such employment; provided, however, that the foregoing shall
not  prevent  ATC or  UniSite  (or  any of  their  respective  Affiliates)  from
soliciting  or actively  seeking to hire any such key employee who (i) initiates
employment  discussions with it, (ii) is not employed by ATC or UniSite,  or any
of their respective  Affiliates,  as the case may be, on the date UniSite or ATC
(or any of their respective Affiliates), as the case may be, first solicits such
key employee,  or (iii) is solicited  through general  advertisement,  including
without limitation on the Internet.

         6.11 Director and Officer Liability and  Indemnification.  For a period
of six (6) years after the  Closing,  ATC shall not, and shall not permit ATI or
any of its Subsidiaries,  including without limitation UniSite, to amend, repeal
or modify  any  provision  in ATI's or any of its  Subsidiaries  certificate  of
incorporation or bylaws relating to the exculpation or indemnification of former
officers  and  directors  (unless  required  by Law),  except  that prior to the
Effective Time, ATI's  certificate of incorporation  shall be amended to provide
the maximum  exculpation  permitted by Section  102(b) of the DCL and to provide
for mandatory  advancement of expenses,  it being the intent of the parties that
the  officers  and  directors  of ATI and its  Subsidiaries,  including  without
limitation  UniSite,  prior to the Closing shall continue to be entitled to such
exculpation and indemnification to the fullest extent permitted under Applicable
Law;  provided,  however,  that  notwithstanding  the  foregoing,  ATI  and  its
Subsidiaries  may be merged with one or more  Entities so long as  substantially
equivalent exculpation and indemnification  provisions are maintained.  ATC will
cause to be  maintained  for a period of not less  than six (6)  years  from the
Effective  Time  UniSite's  current  directors'  and  officers'   insurance  and
indemnification  policies to the extent that they  provide  coverage  for events
occurring prior to the Effective Time (the "D&O  Insurance") for all persons who
are  directors  and officers of UniSite on the date of this  Agreement or at the
Effective Time, so long as the annual premium therefor would not be in excess of
one hundred fifty percent  (150%) of the current  premium.  If any then existing
D&O Insurance  expires,  is terminated or canceled during such six-year  period,
ATC will use its  reasonable  best  efforts to cause to be  obtained as much D&O
Insurance as can be obtained for the  remainder of such period for an annualized
premium  not in  excess  of one  hundred  fifty  percent  (150%),  on terms  and
conditions no less  advantageous  to the covered  Persons than the then existing
D&O Insurance.  Notwithstanding  the foregoing,  ATC or its Subsidiaries may, in
lieu of  maintaining  such  existing  D&O  Insurance  as provided  above,  cause
coverage to be provided  under any policy  maintained for the benefit of ATC and
its Subsidiaries,  including without  limitation  UniSite,  so long as the terms
thereof are, in the  aggregate,  not  materially  less  favorable to the covered
individual than the UniSite policy terms.

         6.12 UniSite Software Expertise.

         (a)  Promptly  after the  execution  and  delivery  of this  Agreement,
UniSite agrees that it will (a) make  available,  from time to time prior to the
Closing upon the request of ATC,  officers and other  employees  involved in the
management  information  systems and  computer  software  operations  of UniSite
(including  without  limitation  Robert  Mowery) to consult  with and assist ATC
personnel  in  installing  and  using  any  and  all  of  UniSite's   management
information   systems  and  computer   software   (collectively,   the  "UniSite
Software"),  and (b) grant to ATC a perpetual non-exclusive royalty-free (except
as hereinafter in this Section provided) license (which license shall, except as
otherwise   provided  in  Section  6.12(b))  survive  the  termination  of  this
Agreement) to use (including  the right to make copies of) the UniSite  Software
in the ordinary course of ATC's tower  business,  to the extent that UniSite has
rights  therein,  UniSite  covenanting  and agreeing to use its reasonable  best
efforts  to  secure  any  third  party  consents  required  to  comply  with the
provisions of this

                                      -29-


<PAGE>



Section. Such perpetual non-exclusive royalty-free license shall include a right
to all updates, improvements and modifications of the UniSite Software made from
time to time by UniSite or any of its Affiliates,  including without  limitation
following the  termination  of this Agreement  (except as otherwise  provided in
Section  6.12(b)).  Such officers and other employees shall be made available by
UniSite  (i) at such  location  or  locations  as ATC  shall,  from time to time
(including subsequent to the termination of this Agreement,  except as otherwise
provided in Section 6.12(b)),  reasonably request, (ii) at no cost or expense to
ATC, other than the  reimbursement by ATC of all of UniSite's  reasonable direct
out-of-pocket costs and expenses (which shall not, in any event,  include wages,
salaries,  fringe benefits or similar expenses), and (iii) in a manner so as not
to  interfere  unreasonably  with the  performance  by such  officers  and other
employees of their duties and responsibilities to UniSite.  Unless and until the
Merger is consummated,  ATC shall not alter,  amend,  modify,  reverse engineer,
integrate  (unless it is able to  disintegrate it should ATC not become entitled
to retain rights with respect to the UniSite Software pursuant to the provisions
of  Section  6.12(b)),  decompile,  disassemble  or  decode  any of the  UniSite
Software.  ATC shall comply with the terms and conditions of any license granted
to UniSite by third parties  pertaining to the UniSite Software of which UniSite
has advised ATC in writing.  Nothing  contained  herein  shall be  construed  as
obligating UniSite to maintain, update, improve, or modify the UniSite Software,
except as it may elect to do so in its sole  discretion  for its own benefit and
use in the ordinary course of its tower  business,  subject,  however,  to ATC's
rights to use such  maintained,  updated,  improved or modified UniSite Software
pursuant to the provisions of this Section.

         (b) In the event this Agreement is terminated, the following provisions
shall govern ATC's rights with respect to the UniSite Software:

                  (i) In the event this Agreement is terminated  pursuant to the
         provisions of paragraph (c) of Section 8.1, and such termination is the
         result of a willful or  intentional  default or willful or  intentional
         breach by ATC, ATC shall have no further rights to the UniSite Software
         and shall surrender all copies of the UniSite  Software and the license
         referred to in Section  6.12(a)  shall  terminate  and be of no further
         force and effect;

                  (ii) In the event this Agreement is terminated pursuant to the
         provisions of (x) paragraph (d) of Section 8.1, and such termination is
         the  result  of  a  willful  or  intentional   default  or  willful  or
         intentional  breach by UniSite,  or (y) paragraph (e) or (f) of Section
         8.1,  ATC  shall  have the right to retain  its  rights to the  UniSite
         Software  and the  license  set forth in Section  6.12(a)  without  the
         requirement of its making any payment to UniSite; and

                  (iii) In the event this  Agreement is terminated for any other
         reason,  including  without  limitation  pursuant to the  provisions of
         paragraphs  (a),  (b),  (c) (for other  than a willful  or  intentional
         default  or  willful  or  intentional  breach) or (d) (for other than a
         willful or  intentional  default or willful or  intentional  breach) of
         Section  8.1,  or Section  10.15 or 10.16,  ATC shall have the right to
         retain its rights to the UniSite  Software set forth in Section 6.12(a)
         without the requirement of its making any payment to UniSite; provided,
         however, that if Omnipoint has not executed and delivered the Omnipoint
         Amendment  or  an  amendment  to  the  Omnipoint   Agreement  on  terms
         substantially  as least as favorable to UniSite in the aggregate as the
         Omnipoint Amendment the following provisions shall apply:

                           (x) if no amendment to the  Omnipoint  Agreement  has
                  been executed and  delivered by Omnipoint,  ATC shall have the
                  right to retain its rights to the UniSite  Software  set forth
                  in  Section  6.12(a)  by the  payment to UniSite of the sum of
                  $15.0 million; and


                                      -30-


<PAGE>



                           (y)  if  Omnipoint  has  executed  and  delivered  an
                  amendment to the  Omnipoint  Agreement  but it is not on terms
                  substantially  at  least  as  favorable  in the  aggregate  to
                  UniSite as the Omnipoint Amendment (and including in any event
                  financing  from  ATC),  ATC shall have the right to retain its
                  rights to the UniSite Software set forth in Section 6.12(a) by
                  the  payment to  UniSite  of the  excess of (I) $15.0  million
                  (which  the  parties  agree  is the  value to  UniSite  of the
                  Omnipoint  Amendment)  and (II) the value of such amendment as
                  agreed to by the  parties  or, in the event they are unable to
                  agree  upon its value  within ten (10)  business  days of good
                  faith negotiation,  as determined by CSFB whose  determination
                  shall be binding and conclusive on the parties.

         (c) UniSite agrees that it will,  promptly upon the written  request of
ATC,  including  prior to the  Effective  Time,  execute  and  deliver to ATC an
assignment  and  license  agreement,  in form,  scope and  substance  reasonably
satisfactory to ATC, setting forth the terms and conditions of this Section.

         6.13  Stockholder  Approval.  UniSite will  establish  the date of this
Agreement  as the record date for,  and duly call,  give notice of,  convene and
hold a meeting of its stockholders (the "UniSite Stockholders  Meeting") for the
purpose of  obtaining  the  approval  and  adoption  of this  Agreement  and the
approval of the Merger by the UniSite  stockholders  in accordance  with the DCL
and other  Applicable  Law and the Organic  Documents of UniSite  (the  "UniSite
Stockholder Approval").  In lieu of calling such a meeting,  UniSite may solicit
written  consents of the UniSite  stockholders  in  accordance  with the DCL and
other Applicable Law and the Organic Documents of UniSite. UniSite covenants and
agrees that the UniSite  Stockholders  Meeting will be held, or written consents
evidencing UniSite Stockholder Approval will be obtained, no later than July 12,
1999.  UniSite  will,   through  its  Board  of  Directors,   recommend  to  its
stockholders approval and adoption of this Agreement and approval of the Merger,
subject to the provisions of Section 6.5.

         6.14 UniSite  Compensation  Plan.  UniSite will, as soon as practicable
following the date hereof,  establish a management  incentive and retention plan
substantially  on the terms and  conditions  set forth in the letter  heretofore
delivered by UniSite to ATC.

         6.15 Structural Reports. As promptly as practicable after the execution
of this  Agreement,  ATC may,  but shall not be  obligated,  at its own cost and
expense,  obtain a report (the "Structural Reports") with respect to each of the
components  of  the  Completed  Towers  of  such  structural  engineers  as  are
reasonably  satisfactory to ATC with respect to (i) the structural soundness and
operating  condition of the Completed  Towers,  (ii) compliance of the Completed
Towers  with  all  Applicable  Laws,  Governmental  Authorizations  and  Private
Authorizations,  and (iii) any required structural or other material repairs. To
the extent ATC fails to initiate  and  diligently  pursue such efforts (and with
respect to existing  Completed  Towers  complete)  within the due  diligence day
period  referred to in Section 10.16 (except for Towers not then owned or Towers
then  under  construction  by  UniSite),  it shall be deemed to have  waived the
condition  set  forth in  Section  7.2(l).  Prior to the  expiration  of the due
diligence  period  referred to in Section  10.16,  ATC shall  advise  UniSite in
writing as to any objections to the matters  revealed in any  Structural  Report
ordered by it pursuant to the provisions of this Section; to the extent that ATC
has  failed to so advise  UniSite as to any  objections,  ATC shall be deemed to
have waived the condition set forth in Section 7.2(l).


                                    ARTICLE 7

                               CLOSING CONDITIONS


                                      -31-


<PAGE>



         7.1 Conditions to Obligations of Each Party. The respective obligations
of each party to consummate the Merger shall, except as hereinafter  provided in
this Section,  be subject to the satisfaction at or prior to the Closing Date of
the  following  conditions,  any or all of which may be  waived,  in whole or in
part, to the extent permitted by Applicable Law:

                  (a) As of the Closing  Date,  no Legal Action shall be pending
         before any  Authority  seeking to enjoin,  restrain,  prohibit  or make
         illegal or to impose any  materially  adverse  condition in  connection
         with, the  consummation of the Merger,  it being  understood and agreed
         that a written request by any Authority for information with respect to
         the Merger,  which  information  could be used in connection  with such
         Legal  Action,  shall not in  itself  be  deemed  to be a Legal  Action
         pending before any such Authority;

                  (b) Any waiting period (and any extension thereof)  applicable
         to the consummation of the Merger under the Hart-Scott-Rodino Act shall
         have expired or been terminated;

                  (c) Except with respect to the Hart-Scott-Rodino Act (which is
         addressed in Section 7.1(b)),  all authorizations,  consents,  waivers,
         orders or approvals  required to be obtained from all Authorities,  and
         all filings (other than those referred to in Section 2.3), submissions,
         registrations,  notices or  declarations  required to be made by any of
         the  parties  with  any  Authority,  prior to the  consummation  of the
         Merger,  shall  have  been  obtained  from,  and  made  with,  all such
         Authorities, except for such authorizations, consents, waivers, orders,
         approvals, filings, submissions, registrations, notices or declarations
         the failure to obtain or make would not have a material  adverse effect
         on UniSite; and

                  (d) The UniSite Stockholder Approval shall have been obtained.

         7.2  Conditions  to  Obligations  of ATC and ATI.  Except as  otherwise
specifically set forth in paragraphs (d), (f), (j) and (l) of this Section,  the
obligation of ATC to cause ATI to, and of ATI to, consummate the Merger shall be
subject to the satisfaction of the following conditions, any or all of which may
be  waived,  in whole  or in part,  by ATC and ATI to the  extent  permitted  by
Applicable Law:

                  (a) All agreements, certificates, opinions and other documents
         required to be delivered  pursuant to the  provisions of this Agreement
         shall be reasonably  satisfactory  in form,  scope and substance to ATC
         and its  counsel,  and ATC and its  counsel  shall  have  received  all
         information and copies of all documents, including records of corporate
         proceedings, which they may reasonably request in connection therewith,
         such documents where appropriate to be certified by proper  Authorities
         or corporate officers;

                  (b) UniSite shall have  furnished  ATC and, at ATC's  request,
         any bank or other financial institution providing credit to ATC, with a
         favorable  opinion,  dated the Closing  Date,  of Holland & Knight LLP,
         counsel for UniSite,  substantially  to the effect  stated in Exhibit D
         and made a part hereof,  and with respect to such other matters arising
         after the date of this  Agreement as ATC or its counsel may  reasonably
         request;

                  (c)  (i)  The   representations   and  warranties  of  UniSite
         contained  in this  Agreement  (other than those  contained in Sections
         4.20) or otherwise made in writing by or on behalf of it or any of them
         pursuant  hereto or otherwise made in connection  with the Merger shall
         be true and correct at and as of the  Closing  Date with the same force
         and  effect as though  made on and as of such  date,  except

                                      -32-


<PAGE>

         (x) to the extent such  representations and warranties  expressly speak
         as  of  an  earlier  date  (in  which  case  such  representations  and
         warranties  shall be true and correct as of such earlier  date) and (y)
         to the extent that the failure of such  representations  and warranties
         to be true and correct,  individually or in the aggregate,  has not had
         and will not have a  material  adverse  effect  on  UniSite;  provided,
         however,  that for the purpose of this clause (y)  representations  and
         warranties that are qualified as to materiality (including by reference
         to "material  adverse  effect") shall not be deemed to be so qualified;
         (ii) the representations and warranties of UniSite set forth in Section
         4.20 shall be true and correct at and as of the  Closing  Date with the
         same force and effect as though made on and as of such date;  provided,
         however,  any untruth shall be disregarded for purposes of this Section
         6.2(c)  if, by  adjusting  the Merger  Consideration  at  Closing,  the
         untruth  is  rendered  harmless  and such  adjustment  either  does not
         require the approval of the UniSite stockholders,  or such approval has
         been  obtained,  in accordance  with the DCL; (iii) each and all of the
         agreements  and  covenants  to be  performed  or  satisfied  by UniSite
         hereunder  at or  prior  to the  Closing  Date  shall  have  been  duly
         performed or satisfied in all material respects; and (iv) UniSite shall
         have  furnished  ATC  with  such   certificates   and  other  documents
         evidencing the truth of such representations, warranties, covenants and
         agreements and the  performance of such agreements or conditions as ATC
         or its counsel shall have reasonably requested;

                  (d)  All (i)  Required  Consents  shall  have  been  obtained;
         provided,  however,  that  ATC's sole  remedy in the event (i)  UniSite
         fails to obtain  any  Required  Consent  and (ii) ATC and  UniSite  are
         unable to negotiate  (which they agree to do in good faith for a period
         of five (5) business days) a mutually agreeable reduction in the Merger
         Consideration  designed  to "make ATC  whole"  for the  failure of this
         condition to be satisfied,  is to reduce the Merger Consideration by an
         amount  equal to the decrease  (but in no event more than  $300,000 for
         each affected  tower) in value of the affected  towers as determined by
         CSFB  whose  determination  shall  be  binding  and  conclusive  on the
         parties, and (ii) all other authorizations,  consents,  waivers, orders
         or  approvals  required  by the  provisions  of  this  Agreement  to be
         obtained  from  all  Persons  (other  than  Authorities)  prior  to the
         consummation of the Merger, including without limitation those required
         in order  for ATI to  continue  to own all of the  UniSite  Assets  and
         continue to operate the UniSite Business as conducted immediately prior
         to the  Closing  shall  have been  obtained,  without  the  imposition,
         individually or in the aggregate,  of any condition or requirement that
         has had or could have a material adverse effect on UniSite;

                  (e) Between the date of this  Agreement  and the Closing Date,
         there shall not have been,  and there shall not  reasonably be expected
         to be  (including  without  limitation  by reason  of giving  pro forma
         effect to (a) any  failure of the  representations  and  warranties  of
         UniSite to be true and correct as provided in Section  7.2(c),  (b) any
         failure  to  obtain  the  authorizations,  consents,  waivers,  orders,
         approvals, filings, submissions, registrations, notices or declarations
         provided  for in Section  7.1(c) and 7.2(d),  (c) any Legal Action of a
         nature referred to in Section  7.2(h),  or (d) any failures of a nature
         referred  to in Section  7.2(l)) a material  adverse  change in UniSite
         from that reflected in the most recent UniSite Financial Statements;

                  (f)  The  Environmental   Reports  prepared  pursuant  to  the
         provisions  of  Section  6.8  shall not raise  questions  of  potential
         liability  that  were not set  forth  in  Section  4.19 of the  UniSite
         Disclosure   Schedule   (including   having   been  set  forth  in  the
         Environmental   Reports  listed   therein)  and  that,  when  taken  in
         conjunction  with any Event or Events that have occurred  subsequent to
         the date hereof,  individually  or in the aggregate,  have had or could
         have  a  material  adverse  effect  on  UniSite,  or  would  cause  the
         representations  and  warranties  of UniSite set forth in Section  4.19
         (without  regard to  knowledge)  to be  inaccurate or incomplete in any
         material  respect;  provided,  however,  that ATC's

                                      -33-


<PAGE>



         sole  remedy in the  event (i)  UniSite  fails to obtain  satisfy  this
         condition and (ii) ATC and UniSite are unable to negotiate  (which they
         agree to do in good  faith  for a period of five (5)  business  days) a
         mutually agreeable  reduction in the Merger  Consideration  designed to
         "make ATC whole" for the failure of this condition to be satisfied,  is
         to reduce the Merger  Consideration  by an amount equal to the decrease
         in value of UniSite as determined by CSFB whose  determination shall be
         binding and conclusive on the parties;  provided further,  however,  in
         the event such decrease is more than $15.0  million  UniSite shall have
         the right not to proceed with the Closing  unless ATC were willing to a
         decrease of not more than $15.0 million;

                  (g) ATC shall have received from its independent accountants a
         letter to the effect that they could issue an unqualified report (as to
         scope, access to books and records, and management  cooperation) on the
         financial statements (consisting of a balance sheet for the fiscal year
         ended December 31, 1999, and statements of operations and cash flow for
         the three (3) years then ended) of UniSite which  financial  statements
         shall have been prepared in  conformity  with GAAP and  Regulation  S-X
         under the Securities Act;

                  (h) As of the Closing  Date,  except as otherwise set forth in
         Section  4.6(a) of the UniSite  Disclosure  Schedule,  no Legal  Action
         shall be pending before any Authority (i) that could,  individually  or
         in the aggregate, in the reasonable business judgment of ATC based upon
         the advice of counsel,  have a material  adverse effect on UniSite,  or
         (ii)  insofar  as it  relates  to the  Merger,  seeking  the  potential
         divestiture  by ATC of any  material  portion  of the  assets of ATC or
         UniSite;

                  (i) Each of the UniSite  stockholders  shall have executed and
         delivered to ATC a certificate of non-foreign status,  substantially in
         the form  attached  hereto  as  Exhibit E and made a part  hereof  (the
         "Non-Foreign Ownership  Certificates"),  it being understood,  however,
         that ATC and ATI shall not have the right to refrain from  consummating
         the  Merger in the event all of such  certificates  shall not have been
         delivered but only to take the action  contemplated  by Section  3.2(f)
         with  respect  to any  UniSite  stockholder  who  does  not  deliver  a
         Non-Foreign Ownership Certificate;

                  (j) ATC shall have received,  at its expense,  a commitment to
         issue standard ALTA title insurance policies insuring UniSite's and, if
         applicable, each of its Subsidiaries' fee and leasehold interest in the
         parcels  of land on  which  any  Completed  Tower  or any  tower  under
         construction  is located and the  improvements  located thereon and the
         Title Report shall not disclose  any  exception,  other than  Permitted
         Liens and Liens,  if any,  set forth on Section  4.4(a) of the  UniSite
         Disclosure  Schedule to which ATC shall not have  objected  pursuant to
         the  provisions  of Section  10.15,  and no Event or Events  shall have
         occurred subsequent to the date hereof,  which,  individually or in the
         aggregate,  would cause the  representations  and warranties of UniSite
         set  forth in  Section  4.4(a)  (without  regard  to  knowledge)  to be
         inaccurate or incomplete in any material  respect;  provided,  however,
         that ATC's sole remedy in the event (i) UniSite  fails to satisfy  this
         condition and (ii) ATC and UniSite are unable to negotiate  (which they
         agree to do in good  faith for a period  of not more than five  days) a
         mutually agreeable  reduction in the Merger  Consideration  designed to
         "make ATC whole" for the failure of this condition to be satisfied,  is
         to reduce the Merger  Consideration  by an amount equal to the decrease
         (but in no event more than $300,000 for each  affected  tower) in value
         of the affected towers as determined by CSFB whose  determination shall
         be binding and conclusive on the parties;

                  (k)  Except  as set  forth in  Section  3.1,  all  Convertible
         Securities  and  Option  Securities  of  UniSite,  if any,  outstanding
         immediately  prior to the Closing,  other than those,  if any, owned by

                                      -34-


<PAGE>



         any  Subsidiary  of UniSite,  shall be canceled and, from and after the
         Closing, shall no longer be of any force or effect;

                  (l) The Structural  Reports,  if any, shall indicate that each
         of the Completed Towers (i) is structurally sound and in good operating
         condition, (ii) is in compliance with all Applicable Laws, Governmental
         Authorizations and Private  Authorizations,  and (iii) does not require
         any structural or other material  repairs,  except where the failure of
         the  Completed  Towers  to meet  the  preceding  standards  would  not,
         individually  or in the  aggregate,  have a material  adverse effect on
         UniSite;  provided,  however,  that ATC's sole  remedy in the event (i)
         UniSite  fails to satisfy this  condition  and (ii) ATC and UniSite are
         unable to negotiate  (which they agree to do in good faith for a period
         of not more than  five  days) a  mutually  agreeable  reduction  in the
         Merger  Consideration  designed  to "make ATC whole" for the failure of
         this condition to be satisfied,  is to reduce the Merger  Consideration
         by an amount equal to the decrease  (but in no event more than $300,000
         for each affected  tower) in value of the affected towers as determined
         by CSFB whose  determination  shall be binding  and  conclusive  on the
         parties;

                  (m) Daniel P.  Behuniak  shall have  executed and delivered to
         ATC an  agreement  substantially  in the form  attached  hereto  as (i)
         Exhibit F-1 and made a part  hereof (the "ATC  [Employment][Consulting]
         Agreement")  and (ii)  Exhibit  F-2 and made a part  hereof  (the  "ATC
         Noncompetition Agreement"); and

                  (n) Each of the employment  agreements  listed in Section 4.14
         of  the   UniSite   Disclosure   Schedule   and  each  of  the  related
         transactions, if any, listed or described in Section 4.8 of the UniSite
         Disclosure Schedule shall have been terminated by UniSite,  except that
         any noncompetition provisions, whether contained in those agreements or
         in separate agreements, shall remain in effect, or amended on the terms
         and conditions reasonably satisfactory to ATC, in each case, at no cost
         or expense to ATC,  except as  provided  in the  definition  of Working
         Capital.

         7.3 Conditions to Obligations of UniSite.  The obligation of UniSite to
consummate  the Merger  shall be subject to the  satisfaction  of the  following
conditions,  any or all of which may be waived,  in whole or in part, by UniSite
to the extent permitted by Applicable Law:

                  (a) All agreements, certificates, opinions and other documents
         required to be delivered  pursuant to the  provisions of this Agreement
         shall be  reasonably  satisfactory  in form,  scope  and  substance  to
         UniSite  and its  counsel,  and  UniSite  and its  counsel  shall  have
         received all information and copies of all documents, including records
         of  corporate  proceedings,   which  they  may  reasonably  request  in
         connection therewith,  such documents where appropriate to be certified
         by proper Authorities or corporate officers;

                  (b)  ATC  shall  have  furnished  UniSite,  with  a  favorable
         opinion,  dated the Closing Date, of Sullivan & Worcester LLP,  counsel
         for ATC,  substantially  in the form  attached  hereto as Exhibit I and
         made a part  hereof,  and with  respect to such other  matters  arising
         after  the  date  of this  Agreement  as  UniSite  or its  counsel  may
         reasonably request;

                  (c)  The   representations  and  warranties  of  ATC  and  ATI
         contained in this Agreement (other than those contained in Section 5.5)
         or otherwise made in writing by them or on their behalf pursuant hereto
         or  otherwise  made in  connection  with the  Merger  shall be true and
         correct in all material respects at and as of the Closing Date with the
         same force and effect as though made on and

                                      -35-


<PAGE>



         as of such  date,  except (x) to the extent  such  representations  and
         warranties  expressly  speak as of an earlier  date (in which case such
         representations  and  warranties  shall be true and  correct as of such
         earlier  date)  and  (y)  to  the  extent  that  the  failure  of  such
         representations and warranties to be true and correct,  individually or
         in the  aggregate,  would not have a  material  adverse  effect on ATC;
         provided,   however,   that  for  the   purpose  of  this   clause  (y)
         representations and warranties that are qualified as to the materiality
         (including  by  reference to "material  adverse  effect")  shall not be
         deemed to be so qualified;  (ii) the  representations and warranties of
         ATC set forth in Section 5.5 shall be true and correct at and as of the
         Closing Date with the same force and effect as though made on and as of
         such date;  provided,  however,  any untruth shall be  disregarded  for
         purposes  of  this  Section   6.3(c)  if,  by   adjusting   the  Merger
         Consideration at Closing, the untruth is rendered harmless;  (iii) each
         and all of the agreements and covenants to be performed or satisfied by
         ATC or ATI  hereunder  at or prior to the Closing  Date shall have been
         duly  performed or satisfied  in all  material  respects;  and (iv) ATI
         shall have furnished UniSite with such certificates and other documents
         evidencing the truth of such representations, warranties, covenants and
         agreements  and the  performance  of such  agreements  or conditions as
         UniSite or its counsel shall have reasonably requested;

                  (d) Between the date of this  Agreement  and the Closing Date,
         there shall not have  occurred and be continuing  any material  adverse
         change in ATC from that  reflected  in the most  recent  ATC  Financial
         Statements;

                  (e) As of the Closing  Date,  no Legal Action shall be pending
         before any Authority which could,  individually or in the aggregate, in
         the  reasonable  business  judgment of UniSite based upon the advice of
         counsel,  be reasonably  expected to have a material  adverse effect on
         ATC;

                  (f)  ATC  shall   have   executed   and   delivered   the  ATC
         Noncompetition Agreements;

                  (g) ATI's  certificate of incorporation  and bylaws shall have
         been amended as provided in Section 6.11; and

                  (h) UniSite  shall have  received an opinion,  addressed to it
         and dated the date of this Agreement, of CSFB to the effect that, as of
         such date, the Merger Consideration is fair to the UniSite stockholders
         from a financial point of view.


                                    ARTICLE 8

                        TERMINATION, AMENDMENT AND WAIVER

         8.1 Termination.  This Agreement may be terminated at any time prior to
the Effective Time only pursuant to the following provisions:

                  (a)      by mutual consent of UniSite and ATC; or

                  (b) by ATC or UniSite if any permanent  injunction,  decree or
         judgment of any Authority  preventing  consummation of the Merger shall
         have become final and nonappealable; or

                  (c) by  UniSite in the event (i)  UniSite  is not in  material
         breach   of  this   Agreement   and   none  of  its  or  any  of  their
         representations  or  warranties  shall have  become and  continue to be
         untrue

                                      -36-


<PAGE>



         in any  manner  that  would  cause the  condition  set forth in Section
         7.2(c) not to be satisfied,  and (ii) either (A) the  Termination  Date
         has occurred without the consummation of the Merger,  or (B) ATC or ATI
         is in material breach of this Agreement or any of their representations
         or  warranties  shall have been or become and  continue to be untrue in
         any manner that would cause the  conditions set forth in Section 7.3(c)
         not to be  satisfied,  and such a breach or  untruth  exists and is not
         capable of being cured by and will prevent or delay consummation of the
         Merger by or beyond the Termination Date; or

                  (d) by ATC in the event (i) neither ATC nor ATI is in material
         breach  of  this  Agreement  and  none  of  their   representations  or
         warranties  shall have  become and  continue to be untrue in any manner
         that would cause the  condition  set forth in Section  7.3(c) not to be
         satisfied,  and (ii)  either  (A) the  Termination  Date  has  occurred
         without the  consummation of the Merger,  or (B) UniSite or any UniSite
         stockholder is in material breach of this Agreement or any of UniSite's
         or any UniSite  stockholder's  representations or warranties shall have
         been or become and continue to be untrue in any manner that would cause
         the  conditions  set forth in Section  7.2(c) not to be satisfied,  and
         such a breach or untruth  exists and is not  capable of being  cured by
         and will prevent or delay  consummation  of the Merger by or beyond the
         Termination; or

                  (e) by ATC if (i) (A) the Board of Directors of UniSite  shall
         have withdrawn,  or adversely modified,  or failed (upon ATC's request)
         to reconfirm  its  recommendation  of the Merger or this  Agreement (or
         determined  to do so); (B) the Board of Directors of UniSite shall have
         determined to recommend to the UniSite  stockholders  that they approve
         an  Alternative  Transaction  other  than  that  contemplated  by  this
         Agreement or shall have determined to accept a Superior Proposal; (C) a
         tender or exchange offer that, if successful,  would result in a Change
         of Control of UniSite and the Board of  Directors  of UniSite  fails to
         recommend that the UniSite stockholders not tender their shares in such
         tender or exchange offer; (D) UniSite, for any reason, fails to call or
         hold the UniSite  Stockholder  Meeting (unless the UniSite  Stockholder
         Approval has otherwise been obtained) prior to the Termination Date; or
         (E) UniSite shall have breached the provisions of Section 6.5, and (ii)
         UniSite enters into an agreement relating to an Alternative Transaction
         within  one  hundred  eighty  (180)  days  of the  termination  of this
         Agreement  pursuant  to  the  provisions  of  this  paragraph  (e)  and
         subsequently   consummates  such  Alternative  Transaction  or  another
         Alternative Transaction with the Person (or any of its Affiliates) that
         is a party to such Alternative Transaction; or

                  (f)  by  UniSite  pursuant  to  and  in  compliance  with  the
         provisions of Section 6.5(e);  provided,  however, that UniSite's right
         to  terminate  this  Agreement  under this  paragraph  (f) shall not be
         available if UniSite has breached or is then in breach of Section 6.5.

         The term  "Termination  Date"  shall mean March 31,  2000 or such other
date as the parties  may,  from time to time,  mutually  agree,  or as otherwise
extended pursuant to the provisions of this Section.

         The right of ATC or UniSite to  terminate  this  Agreement  pursuant to
this Section shall remain  operative and in full force and effect  regardless of
any investigation  made by or on behalf of any party, any Person controlling any
such party or any of their respective  Representatives whether prior to or after
the execution of this Agreement.

         In the event (i) UniSite  desires to terminate this Agreement  pursuant
to the  provisions of Section  8.1(c)(ii)(B),  or ATC desires to terminate  this
Agreement  pursuant  to  the  provisions  of  Section  8.1(d)(ii)(B),   it  (the
"Terminating Party") shall give written notice (the "Termination Notice") to the
other party (the

                                      -37-


<PAGE>



"Alleged  Breaching  Party"),  specifying  (i) whether it  believes  the alleged
breach,  misrepresentation  or default (the "Alleged  Breach")  constituting the
basis of such termination is the result of a willful or intentional default or a
willful or intentional  breach by the Alleged  Breaching  Party, and (ii) in any
event,  specifying in reasonable detail the nature of the Alleged Breach. If the
Alleged Breach is curable,  the Alleged  Breaching Party shall have a reasonable
period,  not exceeding thirty (30) days, to cure the Alleged Breach,  whether or
not such period extends beyond the Termination Date (which shall be deemed to be
extended during such period).  During such period,  or in the event such Alleged
Breach is not curable  during the thirty (30) days following the delivery of the
Termination  Notice,  whether or not such period extends beyond the  Termination
Date (which  shall be deemed to be extended  during  such  period),  the parties
shall  negotiate  in good  faith  in an  attempt  to  amend  the  terms  of this
Agreement,  including without limitation the amount of the Merger Consideration,
to compensate the Terminating Party for the Alleged Breach. In the event (x) the
Alleged  Breach is not cured within such period or curable,  and (y) the parties
are unable to agree upon an amendment to this Agreement, this Agreement shall be
deemed to have been terminated pursuant to the Termination Notice as of its date
and the provisions of Section 8.2(b) shall apply.

         8.2 Effect of  Termination.  Except as provided  in Sections  6.1 (with
respect to confidentiality),  6.3 and 10.2 and this Section, in the event of the
termination  of this  Agreement  pursuant to Section 8.1, this  Agreement  shall
forthwith  become void, there shall be no liability on the part of any party, or
any of their respective  stockholders,  officers or directors,  to the other and
all rights and  obligations of any party shall cease;  provided,  however,  that
such  termination  shall not relieve any party from liability for any willful or
intentional  misrepresentation or breach of any of its warranties,  covenants or
agreements  set  forth  in  this  Agreement.  In the  event  this  Agreement  is
terminated by:

                  (a)   UniSite   pursuant   to  the   provisions   of   Section
         8.1(c)(ii)(B),  and such  termination  is the  result of a  willful  or
         intentional  default or a willful or intentional breach by ATC, UniSite
         shall be entitled to liquidated  damages in the amount of  $25,000,000,
         together with UniSite's reasonable fees and expenses, including without
         limitation,  fees and  expenses of its  investment  bankers,  financial
         advisers,  counsel,  accountants,  banks  and other  lenders  and other
         consultants and agents;

                  (b) ATC pursuant to the  provisions of Section  8.1(d)(ii)(B),
         and such termination is the result of a willful or intentional  default
         or a willful or intentional breach by UniSite, ATC shall be entitled to
         liquidated damages in an amount equal to the sum of (i) $10,000,000 and
         (ii) the value of the  Omnipoint  Amendment  which the parties agree is
         $15,000,000,   together  with  ATC's   reasonable  fees  and  expenses,
         including  without  limitation,  fees and  expenses  of its  investment
         bankers,  financial  advisers,  counsel,  accountants,  banks and other
         lenders and other consultants and agents;

                  (c)   UniSite   pursuant   to  the   provisions   of   Section
         8.1(c)(ii)(B),  and such  termination is not the result of a willful or
         intentional  default or a willful or intentional breach by ATC, UniSite
         shall be entitled to  liquidated  damages in the amount of  $1,000,000,
         representing  the agreed upon amount of UniSite's  reasonable  fees and
         expenses,  including  without  limitation,  fees  and  expenses  of its
         investment bankers, financial advisers, counsel, accountants, banks and
         other lenders and other consultants and agents;

                  (d) ATC pursuant to the  provisions of Section  8.1(d)(ii)(B),
         and such  termination  is not the  result of a willful  or  intentional
         default or a willful or  intentional  breach by  UniSite,  ATC shall be
         entitled  to  liquidated  damages  in an  amount  equal  to the  sum of
         $1,000,000,  representing  the agreed upon  amount of ATC's  reasonable
         fees and expenses,  including without limitation,  fees and

                                      -38-


<PAGE>


         expenses  of  its  investment  bankers,  financial  advisers,  counsel,
         accountants,  banks and other lenders and other consultants and agents;
         and

                  (e) ATC pursuant to the provisions of paragraph (e) of Section
         8.1 or UniSite  pursuant to the  provisions of paragraph (f) of Section
         8.1, ATC shall be entitled to liquidated  damages in an amount equal to
         the sum of (i) $7,500,000 and (ii) the value of the Omnipoint Amendment
         which the parties agree is $15,000,000,  together with ATC's reasonable
         fees and expenses,  including without limitation,  fees and expenses of
         its investment bankers, financial advisers, counsel, accountants, banks
         and other lenders and other consultants and agents.

Notwithstanding the provisions of paragraphs (b) and (e) above, if Omnipoint has
not  executed  and  delivered  the  Omnipoint  Amendment  or an amendment to the
Omnipoint  Agreement  on  terms  substantially  at  least  as  favorable  in the
aggregate to UniSite as the Omnipoint Amendment,  the following provisions shall
apply:

                  (i)  if no  amendment  to the  Omnipoint  Agreement  has  been
         executed and delivered by Omnipoint,  ATC shall not be entitled to, and
         there  shall  be  excluded  from  liquidated  damages  the sum of $15.0
         million  specified in clause (ii) of  paragraphs  (b) or (e) above,  as
         applicable; and

                  (ii) if Omnipoint  has executed and  delivered an amendment to
         the Omnipoint  Agreement but it is not on terms  substantially at least
         as favorable in the  aggregate  to UniSite as the  Omnipoint  Amendment
         (and including in any event  financing from ATC), ATC shall be entitled
         to, and there shall be included in the liquidated  damages specified in
         clause (ii) of paragraphs (b) or (e) above,  as  applicable,  an amount
         equal to the value of such amendment as agreed to by the parties or, in
         the event  they are  unable to agree  upon its  value  within  ten (10)
         business  days of good faith  negotiation,  as determined by CSFB whose
         determination shall be binding and conclusive on the parties.

         The parties  agree that the amounts  specified  above shall  constitute
full payment for any and all damages suffered by the terminating party by reason
of other party's  failure to consummate  the Merger for the reasons  referred to
therein. ATC and UniSite agree in advance that actual damages would be difficult
to  ascertain  and that the rights of ATC and UniSite set forth in this  Section
are a fair and equitable amount to reimburse UniSite or ATC, as the case may be,
for damages sustained due to ATC's or UniSite's failure to consummate the Merger
for the reasons specified in this Section.  Notwithstanding the foregoing,  each
party  shall  have the  right to seek  specific  performance  of this  Agreement
pursuant to the  provisions of Section 10.4,  and, if such breach relates to the
provisions of Section 6.5, to the extent  applicable,  ATC shall have the rights
set forth in that Section.

         Anything in this Section to the contrary  notwithstanding,  the parties
agree that the provisions of Section 6.12 shall govern ATC's rights,  if any, to
the UniSite Software in the event of any termination of this Agreement.


                                    ARTICLE 9

                                    SURVIVAL

         The  covenants  and  agreements  of the  parties  contained  in or made
pursuant to this Agreement or any Collateral  Document shall survive the Closing
(unless any such  covenant or agreement by its express  terms in this  Agreement
does not so survive) and shall remain operative and in full force and effect for
the  statute


                                      -39-


<PAGE>


of limitations  applicable to contractual  obligations.  The representations and
warranties of the parties contained in or made pursuant to this Agreement or any
Collateral Document shall not survive the Closing.


                                   ARTICLE 10

                               GENERAL PROVISIONS


         10.1 Waivers; Amendments. Changes in or additions to this Agreement may
be made,  or compli  ance  with any  term,  covenant,  agreement,  condition  or
provision  set forth herein may be omitted or waived  (either  generally or in a
particular  instance and either  retroactively or prospectively)  with, but only
with,  the  consent in writing of the  parties  hereto.  No delay on the part of
either  party at any time or times in the  exercise of any right or remedy shall
operate as a waiver thereof. Any consent may be given subject to satisfaction of
conditions  stated therein.  The failure to insist upon the strict provisions of
any  covenant,  term,  condition  or other  provision  of this  Agreement  or to
exercise any right or remedy hereunder shall not constitute a waiver of any such
covenant,  term,  condition or other provision  thereof or default in connection
therewith. The waiver of any covenant, term, condition or other provision hereof
or  default  hereunder  shall not affect or alter  this  Agreement  in any other
respect, and each and every covenant, term, condition or other provision of this
Agreement shall, in such event,  continue in full force and effect, except as so
waived,  and shall be  operative  with  respect  to any other then  existing  or
subsequent default in connection herewith.

         10.2 Fees, Expenses and Other Payments. All costs and expenses incurred
in connection  with any transfer  taxes,  sales taxes,  recording or documentary
taxes,  stamps or other charges levied by any Authority in connection  with this
Agreement and the consummation of the Merger and all costs of the  Environmental
Reports referred to in Section 6.6(k) shall be borne by UniSite and reflected in
Working Capital,  all costs of  Environmental  Reports,  Structural  Reports and
Title  Policies  ordered by ATC pursuant to the provisions of Sections 6.8, 6.15
and 7.2(j),  respectively,  shall be borne by ATC, all Hart-Scott-Rodino  filing
fees and expenses,  if any, shall be borne by the party making such filing,  and
all other costs and expenses  incurred in connection with this Agreement and the
consummation of the Merger,  including without limitation fees and disbursements
of counsel,  financial advisors and accountants  incurred by the parties hereto,
shall,  unless otherwise  provided  herein,  be borne solely and entirely by the
party that has incurred such costs and  expenses.  ATC  acknowledges  and agrees
that it shall  pay (a) the  reasonable  fees and  expenses  of CSFB and Fleet in
connection with their acting as financial  advisor to UniSite in connection with
the Merger and a sale of high-yield debt securities,  respectively,  and (b) the
costs of any  Employment  Arrangements  described  in Section  4.14  incurred by
UniSite as a result of the consummation of the Merger, except to the extent such
costs  aggregate  more  than  $2,000,000,  and the  costs  associated  with  the
compensation plan referred to in Section 6.14.

         10.3  Notices.  All  notices  and  other  communications  which  by any
provision of this Agreement are required or permitted to be given shall be given
in writing and shall be deemed to have been delivered (a) five (5) business days
after being mailed by first-class or express mail, postage prepaid, (b) the next
day when sent overnight by recognized  courier  service,  (c) upon  confirmation
when sent by telex,  telegram,  telecopy  or other  form of rapid  transmission,
confirmed by mailing (by first class or express  mail,  postage  prepaid,  or by
recognized courier service) written  confirmation at substantially the same time
as such rapid  transmission,  or (d) upon delivery when personally  delivered to
the receiving  party (which if other than an  individual  shall be an officer or
other  responsible  party  of  the  receiving  party).   All  such  notices  and
communications  shall be mailed, sent or delivered as set forth below or to such
other  person(s),  telex or facsimile  number(s) or


                                      -40-


<PAGE>



address(es)  as the party to receive any such  communication  or notice may have
designated by written notice to the other party.

         (a)      If to ATC or ATI:

                  116 Huntington Avenue
                  Boston, Massachusetts 02116
                  Attention:   Joseph L. Winn, Chief Financial Officer
                  Telecopier No.:  (617) 375-7575

                  with a copy to (which  shall not  constitute  notice to ATC or
                  ATI):

                  Sullivan & Worcester LLP
                  One Post Office Square
                  Boston, Massachusetts 02109
                  Attention:  Norman A. Bikales, Esq.
                  Telecopier No.:  (617) 338-2880

         (b)      If to UniSite:

                  3450 Buschwood Park Drive
                  Suite 250
                  Tampa, Florida 33618
                  Attention:  Daniel Behuniak, Chief Executive Officer
                  Telecopier No.: (813) 915-3654

                  with a copy to (which shall not constitute notice to UniSite):

                  Holland & Knight LLP
                  400 North Ashley Drive
                  Suite 2000
                  Tampa, FL  33602
                  Attn: Michael L. Jamieson, Esq.
                  Telecopier No.: (813) 229-0134

         10.4  Specific  Performance;  Other  Rights  and  Remedies.  Each party
recognizes and agrees that in the event the other party should refuse to perform
any of its  obligations  under this  Agreement or any Collateral  Document,  the
remedy at law would be inadequate and agrees that for breach of such provisions,
each party shall,  in addition to such other  remedies as may be available to it
at law or in equity or as  provided  in Article  8, be  entitled  to  injunctive
relief and to enforce its rights by an action for  specific  performance  to the
extent permitted by Applicable Law. Each party hereby waives any requirement for
security  or the post ing of any bond or other  surety  in  connection  with any
temporary or permanent award of injunctive, mandatory or other equitable relief.
Nothing  herein  contained  shall be  construed  as  prohibiting  any party from
pursuing any other  remedies  available to it pursuant to the provisions of this
Agreement or  Applicable  Law for such breach or  threatened  breach,  including
without limitation the recovery of damages; provided,  however, that none of the
parties shall pursue, and each party hereby waives, any punitive, incidental and
consequential   damages  arising


                                      -41-


<PAGE>


out of this Agreement  (including  without  limitation damages for diminution in
value and loss of anticipated profits).

         10.5 Severability.  If any term or provision of this Agreement shall be
held or deemed  to be, or shall in fact be,  invalid,  inoperative,  illegal  or
unenforceable  as  applied  to  any  particular  case  in  any  jurisdiction  or
jurisdictions,  or in  all  jurisdictions  or  in  all  cases,  because  of  the
conflicting of any provision with any  constitution or statute or rule of public
policy or for any other reason,  such circumstance  shall not have the effect of
rendering the provision or provisions in question invalid, inoperative,  illegal
or unenforceable in any other  jurisdiction or in any other case or circumstance
or of rendering any other  provision or  provisions  herein  contained  invalid,
inoperative,  illegal or  unenforceable to the extent that such other provisions
are not themselves actually in conflict with such constitution,  statute or rule
of public policy, but this Agreement shall be reformed and construed in any such
jurisdiction or case as if such invalid,  inoperative,  illegal or unenforceable
provision had never been contained herein and such provision reformed so that it
would be valid,  operative and  enforceable to the maximum  extent  permitted in
such jurisdiction or in such case.  Notwithstanding the foregoing,  in the event
of any such  determination  the  effect  of which is to  affect  materially  and
adversely any party,  the parties  shall  negotiate in good faith to modify this
Agreement  so as to effect  the  original  intent of the  parties  as closely as
possible to the fullest  extent  permitted by  Applicable  Law in an  acceptable
manner to the end that the  Transactions  are fulfilled and  consummated  to the
maximum extent possible.

         10.6   Counterparts.   This   Agreement  may  be  executed  in  several
counterparts,  each of  which  shall be  deemed  an  original,  but all of which
together shall constitute one and the same  instrument,  binding upon all of the
parties. In pleading or proving any provision of this Agreement, it shall not be
necessary to produce more than one set of such counterparts.

         10.7 Section Headings. The headings contained in this Agreement are for
reference  purposes  only  and  shall  not in any  way  affect  the  meaning  or
interpretation of this Agreement.

         10.8  Governing  Law. The validity,  interpretation,  construction  and
performance of this Agreement  shall be governed by, and construed in accordance
with, the applicable  Laws of the United States of America and the Laws of State
of New York applicable to contracts made and performed in such State and, in any
event, without giving effect to any choice or conflict of Laws provision or rule
that would  cause the  application  of  domestic  substantive  Laws of any other
jurisdiction,  except to the extent the DCL applies to the  Merger.  Anything in
this  Agreement  to the  contrary  notwithstanding,  in the event of any dispute
between the parties which results in a Legal Action,  the prevailing party shall
be  entitled  to  receive  from  the  non-prevailing   party  reimbursement  for
reasonable  legal fees and expenses  incurred by such  prevailing  party in such
Legal Action.

         10.9 Further Acts. Each party agrees that at any time, and from time to
time, before and after the consummation of the transactions contemplated by this
Agreement,  it  will do all  such  things  and  execute  and  deliver  all  such
Collateral  Documents  and other  assurances,  as any other party or its counsel
reasonably  deems  necessary  or  desirable  in order to carry out the terms and
conditions of this  Agreement  and the  transactions  contemplated  hereby or to
facilitate  the enjoyment of any of the rights  created  hereby or to be created
hereunder.

         10.10  Entire  Agreement.  This  Agreement  (together  with the UniSite
Disclosure  Schedule,  the exhibits hereto, and the other documents delivered or
to be delivered in connection herewith)  constitutes the entire agreement of the
parties  with  respect to the subject  matter  hereof and  supersedes  all prior
agreements,   arrangements,   covenants,  promises,  conditions,   undertakings,
inducements, representations, warranties and

                                      -42-


<PAGE>



negotiations,  expressed or implied, oral or written,  between the parties, with
respect  to  the  subject  matter  hereof,   including  without  limitation  any
previously executed confidentiality  agreement,  letter of intent or term sheet.
Each of the parties is a  sophisticated  Person that was advised by  experienced
counsel and, to the extent it deemed  necessary,  other  advisors in  connection
with this Agreement.  Each of the parties hereby  acknowledges  that (a) none of
the  parties  has  relied  or will  rely in  respect  of this  Agreement  or the
transactions   contemplated   hereby  upon  any  document  or  written  or  oral
information  previously furnished to or discovered by it or its representatives,
other than this  Agreement  (or such of the  foregoing  as are  delivered at the
Closing),  (b) there are no covenants or agreements by or on behalf of any party
or any  of  its  respective  Affiliates  or  representatives  other  than  those
expressly set forth in this Agreement and the Collateral Documents,  and (c) the
parties'  respective  rights and obligations  with respect to this Agreement and
the events giving rise thereto will be solely as set forth in this Agreement and
the Collateral Documents. WITHOUT LIMITING THE GENERALITY OF THE FOREGOING, EACH
PARTY  HERETO  AGREES  THAT,  EXCEPT  FOR  THE  REPRESENTATIONS  AND  WARRANTIES
CONTAINED IN THIS  AGREEMENT AND ANY  COLLATERAL  DOCUMENT,  NONE OF THE PARTIES
MAKES ANY OTHER  REPRESENTATIONS  OR WARRANTIES,  AND EACH HEREBY  DISCLAIMS ANY
OTHER  REPRESENTATIONS  OR  WARRANTIES  MADE BY ITSELF  OR ANY OF ITS  OFFICERS,
DIRECTORS,   EMPLOYEES,   AGENTS,   FINANCIAL   AND  LEGAL   ADVISORS  OR  OTHER
REPRESENTATIVES, WITH RESPECT TO THE EXECUTION AND DELIVERY OF THIS AGREEMENT OR
THE TRANSACTIONS CONTEMPLATED HEREBY, NOTWITHSTANDING THE DELIVERY OR DISCLOSURE
TO THE  OTHER  OR THE  OTHER'S  REPRESENTATIVES  OF ANY  DOCUMENTATION  OR OTHER
INFORMATION WITH RESPECT TO ANY ONE OR MORE OF THE FOREGOING.

         10.11  Assignment.  This Agreement shall not be assignable by any party
and any such  assignment  shall be null and void,  except that it shall inure to
the benefit of and be binding  upon any  successor  to any party by operation of
Law,  including by way of merger,  consolidation or sale of all or substantially
all of its assets,  and ATC and ATI may assign its rights and remedies hereunder
to any bank or other  financial  institution  that has loaned funds or otherwise
extended credit to it.

         10.12  Parties in Interest.  This  Agreement  shall be binding upon and
inure  solely to the  benefit of each  party,  and  nothing  in this  Agreement,
express or implied,  is  intended to or shall  confer upon any Person any right,
benefit or remedy of any nature whatsoever under or by reason of this Agreement,
except as otherwise provided in Section 10.11.

         10.13  Mutual  Drafting.  This  Agreement  is the  result  of the joint
efforts of UniSite,  on the one hand,  and ATC and ATI,  on the other hand,  and
each provision hereof has been subject to the mutual  consultation,  negotiation
and  agreement  of the parties and there  shall be no  construction  against any
party based on any  presumption  of that  party's  involvement  in the  drafting
thereof.

         10.14 UniSite Stockholder Representatives. The UniSite stockholders are
hereby deemed to appoint Mark Fowler, Richard Frisbee and Joel Shulman, as their
representatives  (each individually a "UniSite Stockholder  Representatives" and
all collectively,  the "UniSite Stockholder Representatives") to act for them by
way of majority vote of the UniSite Stockholder  Representatives with respect to
all matters  relating to this Agreement,  including  without  limitation (a) all
determinations contemplated by Section 3.5, and (b)the amendment or modification
of this Agreement or any of the Collateral Documents.  A majority in interest of
the  UniSite  stockholders  may,  from time to time,  remove  one or more of the
UniSite   Stockholder   Representatives,   and/or  appoint   additional  UniSite
Stockholder   Representatives.   The  appointment  of  the  UniSite  Stockholder
Representatives is coupled with an interest, is irrevocable (except as otherwise
herein  set  forth),  and  shall  not be  revoked  by the  death,  incompetency,
liquidation,  dissolution or bankruptcy of any

                                      -43-


<PAGE>



UniSite stockholder. No UniSite Stockholder Representative or any agent employed
by any  UniSite  Stockholder  Representative  shall incur any  liability  to any
UniSite  stockholder  by  virtue  of the  failure  or  refusal  of  any  UniSite
Stockholder  Representative  for any  reason to  consummate  the  transac  tions
contemplated  hereby  or  relating  to  the  performance  of  his  other  duties
hereunder,  except for his own actions or  omissions  constituting  fraud or bad
faith.

         10.15    UniSite Disclosure Schedule.

         (a) UniSite will deliver to ATC,  within  fifteen (15) business days of
the execution and delivery of this Agreement,  the UniSite  Disclosure  Schedule
and all other documents  required to be delivered by UniSite pursuant to Article
4 of this Agreement.  ATC shall have the right, for a period commencing upon its
receipt of the UniSite Disclosure Schedule and each other document together with
a letter from UniSite  indicating  that such  delivery  constitutes a "final and
complete"  delivery  pursuant  to this  Section and  terminating  at 11:59 p.m.,
Eastern time, on the later of the  forty-third  (43rd) day following the date of
this  Agreement and the tenth (10th)  business day following  such receipt,  (i)
either to (x) terminate this Agreement, subject to the cure provisions set forth
in Section  10.15(b),  or (y) propose  amendments to this  Agreement,  including
without limitation an adjustment in the Merger Consideration,  designed to "make
it whole", if the UniSite Disclosure Schedule reveals any Event of which ATC was
unaware as of the date of this Agreement, which unknown Events,  individually or
in  the  aggregate,   would,  in  ATC's  reasonable   business  judgment,   make
consummation  of the  Merger  on the  terms  and  conditions  set  forth in this
Agreement not in the best interests of ATC and its stockholders,  (ii) to object
to Liens  shown in  Section  4.4(a)  of the  Disclosure  Schedule  that  UniSite
proposes to remain in effect at the Effective Time pursuant to the provisions of
Section 7.2(j).

         (b) In the event ATC desires to terminate  this  Agreement  pursuant to
the provisions of Section 10.15(a), it shall in its notice to UniSite specify in
reasonable detail the reasons for such termination.  If the reasons so specified
relate to matters that are curable,  UniSite shall have a reasonable period, not
exceeding  thirty  (30) days,  to effect  such  cure.  In the event such cure is
effected  to the  reasonable  satisfaction  of ATC  within  such  period,  ATC's
termination of this  Agreement  shall be deemed to have been rescinded and of no
further  force and  effect.  In the event (i) the reasons so  specified  are not
curable or (ii)  UniSite is  unwilling  or unable to effect the cure in a timely
manner,  UniSite  shall  also  have the  right  to  propose  amendments  to this
Agreement,   including   without   limitation   an   adjustment  in  the  Merger
Consideration,  designed  to "make ATC whole".  If ATC  rejects  any  amendments
proposed  to this  Agreement  by UniSite  pursuant  to this  Section or Sections
10.16(a) or 10.16(b),  the parties shall promptly  submit the matter to CSFB and
request its recommendation of an appropriate resolution.  ATC agrees to consider
any CSFB  recommendation  in good faith and to  rescind  its  termination  if it
considers such recession appropriate.

         (c) In the  event  (i) the  reasons  for  termination  by ATC  were not
curable  or  UniSite  was  unwilling  or unable  to effect  the cure in a timely
manner,  or (ii)  UniSite  does not agree to the terms and  conditions,  if any,
proposed by ATC  pursuant to clause  (ii) of Section  10.15(a),  UniSite and ATC
shall be obligated  to  negotiate  in good faith with respect to resolving  such
matters.  In the event ATC and UniSite do not agree in writing on the resolution
of matters raised by any proposal made by ATC pursuant to clauses (i)(y) or (ii)
of Section 10.15(a) or by UniSite pursuant to the provisions of Section 10.16(b)
prior to the later of (x) the  expiration  of any cure  period  provided  for in
Section  10.16(b) or (y) ten (10)  business days after receipt by UniSite of any
such  proposal  of ATC or,  in the  event  ATC has not made  any such  proposal,
receipt by ATC of any such proposal of UniSite, either party may, on or prior to
five (5) business days following such later date,  terminate this Agreement.  In
the event  neither  party shall have so terminated  this  Agreement,  or, in the
event ATC makes no proposal pursuant to the provisions of clauses (i)(y) or (ii)
of Section 10.15(a), this Agreement shall continue in full force and effect.


                                      -44-


<PAGE>



         10.16    ATC Completion of Due Diligence.

         (a) On or prior to the  forty-third  (43rd) day  following  the date of
this  Agreement,  ATC  shall  have  completed  its due  diligence  investigation
(including,  except as otherwise  provided in Section  6.7,  6.8 or 6.15,  Title
Reports,  Environmental  Reports  and  Structural  Reports)  of UniSite  and the
UniSite Assets and the UniSite Business.  In the event its due diligence reveals
any  Event of which  ATC was  unaware  as of the date of this  Agreement,  which
unknown  Events,  individually or in the aggregate,  would, in ATC's  reasonable
business  judgment,  make consummation of the Merger on the terms and conditions
set  forth  in  this  Agreement  not in  the  best  interests  of  ATC  and  its
stockholders  ATC shall have the right, at any time prior to 11:59  p.m.,Eastern
time, on the forty-third  (43rd) day following the date of this Agreement either
to (i) terminate  this  Agreement,  subject to the cure  provisions set forth in
Section  10.16(b),  or (ii)  propose  amendments  to this  Agreement,  including
without limitation an adjustment in the Merger Consideration,  designed to "make
it whole".

         (b) In the event ATC desires to terminate  this  Agreement  pursuant to
the provisions of Section 10.16(a), it shall in its notice to UniSite specify in
reasonable detail the reasons for such termination.  If the reasons so specified
relate to matters that are curable,  UniSite shall have a reasonable period, not
exceeding  thirty  (30) days,  to effect  such  cure.  In the event such cure is
effected  to the  reasonable  satisfaction  of ATC  within  such  period,  ATC's
termination of this  Agreement  shall be deemed to have been rescinded and of no
further  force and  effect.  In the event (i) the reasons so  specified  are not
curable or (ii)  UniSite is  unwilling  or unable to effect the cure in a timely
manner,  UniSite  shall  also  have the  right  to  propose  amendments  to this
Agreement,   including   without   limitation   an   adjustment  in  the  Merger
Consideration, designed to "make ATC whole".

         (c) In the  event  (i) the  reasons  for  termination  by ATC  were not
curable  or  UniSite  was  unwilling  or unable  to effect  the cure in a timely
manner,  or (ii)  UniSite  does not agree to the terms and  conditions,  if any,
proposed by ATC  pursuant to clause  (ii) of Section  10.16(a),  UniSite and ATC
shall be obligated  to  negotiate  in good faith with respect to resolving  such
matters.  In the event ATC and UniSite do not agree in writing on the resolution
of matters raised by any proposal made by ATC pursuant to clause (ii) of Section
10.16(a) or by UniSite  pursuant to the provisions of Section  10.16(b) prior to
the later of (x) the  expiration  of any cure  period  provided  for in  Section
10.16(b)  or (y) ten (10)  business  days  after  receipt by UniSite of any such
proposal of ATC or, in the event ATC has not made any such proposal,  receipt by
ATC of any such  proposal of UniSite,  either party may, on or prior to five (5)
business days following such later date, terminate this Agreement.  In the event
neither party shall have so terminated this Agreement, or, in the event ATC does
not terminate this Agreement, and makes no proposal,  pursuant to the provisions
of clause (ii) of Section 10.16(a),  this Agreement shall continue in full force
and effect.


                    [SIGNATURES APPEAR ON THE FOLLOWING PAGE]










                                      -45-


<PAGE>



         IN WITNESS WHEREOF,  the parties have executed this Agreement or caused
this  Agreement  to be  executed by their  respective  officers  thereunto  duly
authorized as of the date first written above.

                               American Tower Corporation


                               By:____________________________________
                                    Name:  James S. Eisenstein
                                    Title: Corporate Development Officer

                               ATI Merger Corporation


                               By:_____________________________________
                                    Name:  James S. Eisenstein
                                    Title: Corporate Development Officer

                               UniSite, Inc.


                               By:______________________________________
                                    Name:  Daniel P. Behuniak
                                    Title: President and Chief Executive Officer



                                      -46-


<PAGE>




                                                                      APPENDIX A

                                   DEFINITIONS

         adverse,  adversely, when used alone or in conjunction with other terms
(including  without  limitation  "affect," "change" and "effect") shall mean any
Event which is reasonably  likely,  in the reasonable  business  judgment of the
relevant  party,  to be  expected  to  (a)  adversely  affect  the  validity  or
enforceability  of this  Agreement  or the  likelihood  of  consummation  of the
Merger, or (b) adversely affect the business, operations, management, properties
or prospects,  or the condition,  financial or other, or results of operation of
UniSite  and  its  Subsidiaries,  if  any,  taken  as a  whole  or ATC  and  its
Subsidiaries,  taken as a whole,  as  applicable,  or (c)  impair  such  party's
ability to fulfill its  obligations  under the terms of this  Agreement,  or (d)
adversely  affect the  aggregate  rights and  remedies  of such party under this
Agreement.  Notwithstanding the foregoing, and anything in this Agreement to the
contrary notwithstanding, any Event generally affecting the economy or the tower
communication  sites business,  shall not be deemed to constitute such a change,
affect or effect.

         Affiliate,  Affiliated shall mean, with respect to any Person,  (a) any
other Person at the time  directly or indirectly  controlling,  controlled by or
under direct or indirect  common control with such Person,  (b) any other Person
of which such Person at the time owns, or has the right to acquire,  directly or
indirectly,  ten  percent  (10%) or more of any  class of the  capital  stock or
beneficial  interest,  (c) any other Person  which at the time owns,  or has the
right to acquire, directly or indirectly, five percent (5%) or more of any class
of the capital  stock or beneficial  interest of such Person,  (d) any executive
officer or director of such Person,  (e) with respect to any partnership,  joint
venture or similar Entity,  any general partner thereof,  and (f) when used with
respect  to an  individual,  shall  include  any  member  of  such  individual's
Immediate Family or a family trust.

         Agreement shall mean this Agreement as originally in effect, including,
unless the context otherwise specifically requires, this Appendix A, the UniSite
Disclosure  Schedule,  and all exhibits hereto,  and as any of the same may from
time to time be supplemented, amended, modified or restated in the manner herein
or therein provided.

         Alleged Breach shall have the meaning given to it in Section 8.1(a).

         Alleged  Breaching  Party shall have the meaning given to it in Section
8.1(a).

         Alternative  Transaction shall mean any proposal or offer relating to a
merger,  consolidation,  reorganization,  tender offer, share exchange, business
combination,  recapitalization,  liquidation, dissolution or similar transaction
involving,  or any purchase of all or any substantial  portion of the assets of,
or any issue,  purchase or sale of equity securities of, or any transaction that
would involve the Change of Control or potential  Change of Control of,  UniSite
or  any of its  Subsidiaries,  or any  series  of  related  transactions  of the
foregoing nature.

         Applicable Law shall mean any Law of any Authority, whether domestic or
foreign,  including without limitation those regulating the safety and structure
of towers, the licensing and regulation of telecommunications  transmissions and
all federal and state  securities and  Environmental  Laws, to which a Person is
subject or by which it or any of its business or operations is subject or any of
its property or assets is bound.

         ATC shall have the meaning given to it in the Preamble.

         ATC [Employment][Consulting]  Agreement shall have the meaning given to
it in Section 7.2(m).


                                       A-1


<PAGE>



         ATC Financial  Statements shall have the meaning given to it in Section
5.2.

         ATC  Indemnified  Parties shall have the meaning given to it in Section
9.2(a).

         ATC  Noncompetition  Agreement  shall have the  meaning  given to it in
Section 7.2(m).

         ATC SEC Documents shall have the meaning given to it in Section 5.2.

         ATC's  knowledge  (or words of  similar  import)  shall mean the actual
knowledge of any director or executive  officer of ATC or ATI, as such knowledge
exists on the date of this Agreement, after reasonable review of appropriate ATC
and  ATI  records  and  after  reasonable  inquiry  of  appropriate  ATC and ATI
employees.

         ATI shall have the meaning given to it in the Preamble.

         AT&T  Agreement  shall mean the Site  Acquisition  Services  Agreement,
dated  September  21, 1998, by and between  UniSite and AT&T Wireless  Services,
Inc.

         Authority shall mean any governmental or quasi-governmental  authority,
whether  administrative,  executive,  judicial,  legislative  or  other,  or any
combination   thereof,   including  without   limitation  any  federal,   state,
territorial,   county,   municipal  or  other   government  or  governmental  or
quasi-governmental agency, arbitrator,  authority,  board, body, branch, bureau,
or comparable  agency or Entity,  commission,  corporation,  court,  department,
instrumentality,  mediator, panel, system or other political unit or subdivision
or other Entity of any of the foregoing, whether domestic or foreign.

         Benefit Arrangement shall mean any material benefit arrangement that is
not a Plan,  including  (a) any  employment  or  consulting  agreement,  (b) any
arrangement providing for insurance coverage or workers' compensation  benefits,
(c) any  incentive  bonus or deferred  bonus  arrangement,  (d) any  arrangement
providing termination  allowance,  severance or similar benefits, (e) any equity
compensation  plan, (f) any deferred  compensation  plan,  (g) any  compensation
policy  and  practice,  and  (h)  any  retirement  benefit,   including  without
limitation  medical,  dental,  health,   disability,   hospitalization  or  life
insurance or reimbursement agreement.

         Broadband  wireless  service  provider shall mean any Entity  providing
wireless  communications  services  generally to consumers,  including PCS, SMR,
ESMR and cellular services.

         BTS Agreement  shall mean an agreement,  other than the AT&T  Agreement
and  the  Omnipoint  Agreement,   pursuant  to  which  UniSite  would  construct
communication  tower(s)  that (a) have at least one broadband  wireless  service
provider as a tenant  pursuant to lease terms no less  favorable to UniSite than
those that UniSite  currently enjoys in the region in which the towers are to be
constructed,  and (b) have the  capacity  to  accommodate  not  less  than  four
broadband wireless service providers.

         Certificate shall have the meaning given to it in Section 3.1.

         Change of Control shall mean the  acquisition,  directly or indirectly,
by any Person or group (as such term is used in Section 13(d)(3) of the Exchange
Act),  other than any existing UniSite  stockholder,  of twenty percent (20%) or
more of the UniSite voting stock.


                                       A-2


<PAGE>



         Claims shall mean any and all debts, liabilities,  obligations, losses,
damages,  deficiencies,  assessments  and  penalties,  together  with all  Legal
Actions, pending or threatened, claims and judgments of whatever kind and nature
relating  thereto,  and all fees, costs,  expenses and disbursements  (including
without  limitation  reasonable  attorneys'  and  other  legal  fees,  costs and
expenses) relating to any of the foregoing.


         Closing shall have the meaning given to it in Section 2.2.

         Closing Date shall have the meaning given to it in Section 2.2.

         COBRA shall mean the Consolidated Omnibus Budget  Reconciliation Act of
1985,  as  amended,  as set  forth  in  Section  4980B of the Code and Part 6 of
Subtitle B of Title I of ERISA and the rules and regulations thereunder,  all as
from time to time in effect, or any successor law, rules or regulations, and any
reference  to any  statutory  or  regulatory  provision  shall be deemed to be a
reference to any successor statutory or regulatory provision.

         Code shall mean the Internal  Revenue  Code of 1986,  and the rules and
regulations  thereunder,  all as from time to time in effect,  or any  successor
Law,  rules or  regulations,  and any  reference to any  statutory or regulatory
provision  shall be deemed  to be a  reference  to any  successor  statutory  or
regulatory provision.

         Collateral Documents shall mean the ATC Noncompetition  Agreement,  the
Non-Foreign  Ownership  Certificates,  the UniSite Notes,  the UniSite  Security
Agreement,  the  Certificate of Merger,  and any other  agreement,  certificate,
contract, instrument, notice, opinion or other document delivered or required to
be delivered  pursuant to the  provisions  of this  Agreement or any  Collateral
Document.

         Completed  Towers shall mean each tower owned,  or subject to a capital
lease with a nominal  purchase price held,  directly or indirectly by UniSite or
any of its Subsidiaries  that is fully  operational and (a) whose acquisition is
permitted or was approved by ATC pursuant to the  provisions of Section 6.6, (b)
was constructed by UniSite pursuant to the Construction Guidelines, (c) is owned
by UniSite or any of its  Subsidiaries  on the date of this Agreement and listed
in Section 4.4(a) of the UniSite Disclosure Schedule,  or (d) was constructed by
UniSite  pursuant  to the  Omnipoint  Agreement,  the  AT&T  Agreement  or a BTS
Agreement approved by ATC pursuant to the provisions of Section 6.6.

         Confidential  Information shall have the meaning given to it in Section
6.1(a).

         Construction  Guidelines shall mean, with respect to any tower proposed
to be  constructed by UniSite,  other than pursuant to the Omnipoint  Agreement,
the AT&T Agreement or a BTS Agreement approved by ATC pursuant to the provisions
of Section 6.6, that such tower meets the following requirements: (a) such tower
will be not less  than 150  feet in  height;  (b)  there is no  competing  tower
existing,  under  construction or, to UniSite's or ATC's knowledge (as set forth
in ATC's  database  and made  available  to  UniSite  by  ATC),  proposed  to be
constructed  within one (1) mile of such tower; (c) based on UniSite's  informed
knowledge  of the  market in which such  tower is  proposed  to be built and the
prospective Broadband wireless activity in such market, it is reasonably certain
that there is a reasonable  demand then existing for Broadband  wireless service
provider  leases in such  market  and that any lease of  antennae  space on such
tower will  provide for (i) minimum  monthly  rental of not less than $1,300 and
preferably  $1,500,  (ii)  annual  rent  escalators  of  not  less  than  3% and
preferably 4%, (iii) a minimum term of not less than five (5) and preferably ten
(10) years,  and (iv) other terms no less  favorable  to UniSite than those that
UniSite  currently  enjoys in the region in which such tower is  proposed  to be
built,  and (d) such tower will have the capacity to  accommodate  not less than
four Broadband wireless service providers.


                                       A-3


<PAGE>



         Contract, Contractual Obligation shall mean any agreement, arrangement,
commitment,  contract, covenant,  indemnity,  undertaking or other obligation or
liability  to which  UniSite or any of its  Subsidiaries  is a party or to which
UniSite or any of its Subsidiaries or any of the UniSite Assets is subject.

         Control (including the terms  "controlled,"  "controlled by" and "under
common control with") means the possession, directly or indirectly or as trustee
or executor,  of the power to direct or cause the direction of the management or
policies of a Person,  or the disposition of such Person's assets or properties,
whether through the ownership of stock, equity or other ownership,  by contract,
arrangement or understanding,  or as trustee or executor,  by contract or credit
arrangement or otherwise.

         Convertible Securities shall mean any evidences of indebtedness, shares
of capital  stock  (other than  common  stock) or other  securities  directly or
indirectly  convertible into or exchangeable for shares of common stock, whether
or not the right to convert or exchange thereunder is immediately exercisable or
is conditioned  upon the passage of time, the  occurrence or  non-occurrence  or
existence or non-existence of some other Event, or both.

         CSFB shall have the meaning given to it in Section 4.18.

         DCL shall have the meaning given to it in Section 2.1.

         Disbursing Agent shall have the meaning given to it in Section 3.2(b).

         Dissenting Shares shall have the meaning given to it in Section 3.6(a).

         Distribution   shall  mean,  with  respect  to  any  Person,   (a)  the
declaration or payment of any dividend (except dividends payable in common stock
of such Person) on or in respect of any shares of any class of capital  stock of
such Person or any shares of capital stock of any  Subsidiary  owned by a Person
other  than such  Person  or a  Subsidiary  of such  Person,  (b) the  purchase,
redemption  or other  retirement  of any shares of any class of capital stock of
such  Person or any shares of capital  stock of any  Subsidiary  of such  Person
owned by a Person other than such Person or a Subsidiary of such Person, and (c)
any other  distribution  on or in  respect of any shares of any class of capital
stock of such Person or any shares of capital  stock of any  Subsidiary  of such
Person owned by a Person other than such Person or a Subsidiary of such Person.

         Effective Time shall have the meaning given to it in Section 2.3.

         Employment  Arrangement  shall  mean,  with  respect  to  UniSite,  any
employment,  consulting,  retainer,  severance or similar  contract,  agreement,
plan,  arrangement or policy (exclusive of any which is terminable within thirty
(30) days without liability, penalty or payment of any kind by UniSite or any of
its Affiliates),  or providing for severance,  termination  payments,  insurance
coverage  (including  any  self-insured  arrangements),   workers  compensation,
disability benefits, life, health, medical, dental or hospitalization  benefits,
supplemental unemployment benefits,  vacation or sick leave benefits, pension or
retirement benefits or for deferred compensation, profit-sharing, bonuses, stock
options,  stock  purchase or  appreciation  rights or other  forms of  incentive
compensation or  post-retirement  insurance,  compensation  or benefits,  or any
collective  bargaining  or  other  labor  agreement,  whether  or not any of the
foregoing is subject to the provisions of ERISA,  but only to the extent that it
covers or relates to any  officer,  employee  or other  Person  involved  in the
ownership  or  operation  of the  UniSite  Assets or the  conduct of the UniSite
Business.

         Encumber  shall  mean  to  suffer,  accept,  agree  to  or  permit  the
imposition of a Lien.


                                       A-4


<PAGE>



         Entity shall mean any corporation,  firm, unincorporated  organization,
association,  partnership,  limited  liability  company,  trust  (inter vivos or
testamentary),  estate of a deceased, insane or incompetent individual, business
trust,  joint stock  company,  joint  venture or other  organization,  entity or
business,  whether acting in an individual,  fiduciary or other capacity, or any
Authority.

         Environmental Law shall mean any Law relating to or otherwise  imposing
liability or  standards of conduct  concerning  pollution or  protection  of the
environment,   including   without   limitation   Laws  relating  to  emissions,
discharges,  releases or  threatened  releases of  Hazardous  Materials or other
chemicals or  industrial  pollutants,  substances,  materials or wastes into the
environment (including,  without limitation,  ambient air, surface water, ground
water,  mining or reclamation or mined land, land surface or subsurface  strata)
or otherwise relating to the manufacture,  processing, generation, distribution,
use, treatment, storage, disposal, cleanup, transport or handling of pollutants,
contaminants,  chemicals or industrial, toxic or hazardous substances, materials
or wastes. Environmental Laws shall include without limitation the Comprehensive
Environmental  Response,  Compensation and Liability Act (42 U.S.C. Section 6901
et seq.)  ("CERCLA"),  the  Hazardous  Material  Transportation  Act (49  U.S.C.
Section  1801 et seq.),  the Resource  Conservation  and Recovery Act (42 U.S.C.
Section 9601 et seq.)  ("RCRA"),  the Federal  Water  Pollution  Control Act (33
U.S.C.  Section  1251 et seq.),  the Clean Air Act (42  U.S.C.  Section  7401 et
seq.),  the Toxic Substances  Control Act (15 U.S.C.  Section 2601 et seq.), the
Occupational Safety and Health Act (29 U.S.C.  Section 651 et seq.), the Federal
Insecticide  Fungicide and Rodenticide Act (7 U.S.C.  Section 136 et seq.),  and
the Surface Mining Control and Reclamation  Act of 1977 (30 U.S.C.  Section 1201
et seq.), and any analogous federal, state, local or foreign Laws, and the rules
and regulations  promulgated  thereunder all as from time to time in effect, and
any reference to any statutory or regulatory  provision  shall be deemed to be a
reference to any successor statutory or regulatory provision.

         Environmental Permit shall mean any Governmental Authorization required
by or pursuant to any Environmental Law.

         Environmental  Report  shall  have the  meaning  given to it in Section
4.19.

         ERISA shall mean the Employee  Retirement  Income Security Act of 1974,
and the rules and regulations thereunder, all as from time to time in effect, or
any successor law, rules or  regulations,  and any reference to any statutory or
regulatory  provision  shall  be  deemed  to be a  reference  to  any  successor
statutory or regulatory provision.

         ERISA  Affiliate  shall  mean any  Person  that is  treated as a single
employer  with UniSite  under  Sections  414(b),  (c), (m) or (o) of the Code or
Section 4001(b)(1) of ERISA.

         Event  shall  mean the  existence  or  occurrence  of any act,  action,
activity,  circumstance,  condition,  event,  fact,  failure  to act,  omission,
incident or practice, or any set or combination of any of the foregoing.

         Exchange Act shall mean the  Securities  Exchange Act of 1934,  and the
rules and  regulations  thereunder,  all as from time to time in effect,  or any
successor  law,  rules or  regulations,  and any  reference to any  statutory or
regulatory  provision  shall  be  deemed  to be a  reference  to  any  successor
statutory or regulatory provision.

         Excluded  Liabilities shall mean any obligation or liability of UniSite
or any of its Subsidiaries  with respect to (a) unfunded pension costs as of the
Effective time, (b) any Employment Arrangement (including without limitation any
obligation to any UniSite  Employee for  severance  benefits or vacation time or
sick leave) with any UniSite  Employee who is terminated by UniSite prior to the
Effective  Time  or  who  does  not  become  an  employee  of  ATI or one of its
Subsidiaries or who,  having become such an employee,  terminates


                                       A-5


<PAGE>



his employment  without cause within ninety (90) days of the Effective Time, and
(c) any of the agreements  listed in the UniSite  Disclosure  Schedule under the
heading "Nonassumed Contracts" .

         Fleet shall have the meaning given to it in Section 4.18.

         GAAP shall mean generally accepted  accounting  principles applied on a
consistent  basis,  (i) as set forth in  Opinions of the  Accounting  Principles
Board of the American Institute of Certified Public Accountants ("AICPA") and/or
in statements of the Financial Accounting Standards Board that are applicable in
the  circumstances as of the date in question,  (ii) when not inconsistent  with
such  opinions  and  statements,  as set forth in other AICPA  publications  and
guidelines  and/or  (iii)  that  otherwise  arise by custom  for the  particular
industry, all as the same shall exist on the date of this Agreement.

         Governmental  Authorizations  shall  mean all  approvals,  concessions,
consents,   franchises,   licenses,  permits,  plans,  registrations  and  other
authorizations  of all  Authorities,  including  without  limitation  the United
States Forest Service and the Federal  Aviation  Administration  and the Federal
Communications  Commission, in connection with the ownership or operation of the
UniSite Assets or the conduct of the UniSite Business.

         Governmental  Filings shall mean all filings,  including  franchise and
similar Tax  filings,  and the payment of all fees,  assessments,  interest  and
penalties associated with such filings, with all Authorities.

         GTE Management  Agreement shall mean the Wireless  Communications  Site
Services Agreement between GTE Mobilnet Incorporated,  GTE Mobile Communications
Incorporated  and Contel  Cellular  Inc., on the one hand,  and UniSite,  on the
other hand, dated July 31, 1996.

         Hart-Scott-Rodino Act shall mean the Hart-Scott-Rodino  Improvement Act
of 1976, as from time to time in effect, or any successor law, and any reference
to any  statutory  provision  shall be deemed to be a reference to any successor
statutory provision.

         Hazardous  Materials  shall mean and include any  substance,  material,
waste, constituent, compound, chemical, natural or man-made element or force (in
whatever state of matter):  (a) the presence of which requires  investigation or
remediation under any Environmental  Law; or (b) that is defined as a "hazardous
waste", "hazardous substance",  "hazardous chemical", "pollutant or contaminant"
or "solid waste" under any  Environmental  Law; or (c) gasoline,  diesel fuel or
other  petroleum  hydrocarbons,  or any  by-products  or fractions  thereof,  or
natural gas; or (d)  asbestos-containing  materials  ("ACM"),  urea formaldehyde
foam insulation polychlorinated biphenyls ("PCBs") and PCB-containing equipment,
or isomer of dioxin,  or any  material or thing  containing  or composed of such
substance or substances;  or (e) radon or other radioactive  elements,  ionizing
radiation,  electromagnetic  field radiation and other  non-ionizing  radiation,
sonic  forces  and other  natural  forces;  or (f) any  infectious  organism  or
biological or medical waste; or (g) that is subject to any Environmental Law.

         Immediate Family shall mean, with respect to any individual, his or her
spouses, past or present, children, parents and siblings, and any of the spouses
of the foregoing,  past or present,  in all cases whether  related by blood,  by
adoption or by marriage

         Indebtedness  for Money Borrowed  shall mean,  with respect to UniSite,
(i) money borrowed,  (ii)  indebtedness  represented by notes payable and drafts
accepted  representing  extensions  of credit,  (iii)  obligations  evidenced by
bonds, debentures,  notes or other similar instruments,  (iv) the maximum amount
currently or at any time thereafter  available to be drawn under all outstanding
letters of credit issued for the account of such Person,  (v) indebtedness  upon
which  interest  charges  are  customarily   paid  by  such  Person,   and  (vi)
indebtedness (including capitalized lease obligations) issued or assumed as full
or partial  payment for

                                       A-6


<PAGE>



property  or  services,  in each case  whether  or not any such  notes,  drafts,
obligations or indebtedness  represents  indebtedness  for money  borrowed,  but
shall not include  (a) trade  payables,  (b)  expenses  accrued in the  ordinary
course of business, (c) customer advance payments and customer deposits received
in the ordinary  course of business,  or (d)  conditional  sales  agreements not
prohibited by the terms of this Agreement.

         Intangible  Assets shall mean all assets and property  lacking physical
properties the evidence of ownership of which must  customarily be maintained by
independent  registration,  documentation,  certification,  recordation or other
means,  and  shall  include,   without  limitation,   concessions,   copyrights,
franchises,  licenses,  permits,  and  applications  with  respect to any of the
foregoing, technology and know-how and other Intellectual Property.

         Intellectual  Property  shall mean any and all  research,  information,
inventions,  designs,  procedures,  developments,   discoveries,   improvements,
patents and applications therefor, trademarks and applications therefor, service
marks, trade names, copyrights and applications therefor,  logos, trade secrets,
drawing, plans, systems,  methods,  specifications,  computer software programs,
tapes, discs and related data processing  software (including without limitation
object and source  codes)  owned by such Person or in which it has an  ownership
interest  and all other  manufacturing,  engineering,  technical,  research  and
development data and know-how made, conceived, developed and/or acquired by such
Person,  which  relate  to the  manufacture,  production  or  processing  of any
products  developed  or sold by such  Person or which are within the scope of or
usable in connection  with such Person's  business as it may, from time to time,
hereafter be conducted or proposed to be conducted.

         Law shall mean any (a) administrative,  judicial,  legislative or other
action,  code,  consent  decree,  constitution,  decree,  directive,  enactment,
finding, law, injunction,  interpretation,  judgment,  order, ordinance,  policy
statement, proclamation,  promulgation,  regulation,  requirement, rule, rule of
law,  rule of  public  policy,  settlement  agreement,  statute,  or writ of any
Authority, domestic or foreign; (b) the common law, or other legal precedent; or
(c)  arbitrator's,   mediator's  or  referee's  award,   decision,   finding  or
recommendation.

         Lease  shall mean any lease of  property,  whether  real,  personal  or
mixed, and all amendments thereto,  and shall include without limitation all use
or occupancy agreements.

         Legal  Action  shall  mean,  with  respect to any  Person,  any and all
litigation   or   legal   or   other   actions,   arbitrations,   counterclaims,
investigations, proceedings, requests for material information by or pursuant to
the  order of any  Authority  or  suits,  at law or in  arbitration,  equity  or
admiralty,  whether or not  purported  to be  brought on behalf of such  Person,
affecting such Person or any of such Person's business, property or assets.

         Lien shall mean any of the  following:  mortgage;  lien  (statutory  or
other);  or other security  agreement,  arrangement or interest;  hypothecation,
pledge  or  other  deposit  arrangement;  assignment;  charge;  levy;  executory
seizure;   attachment;   garnishment;   encumbrance   (including  any  easement,
exception,  reservation or limitation,  right of way, and the like); conditional
sale,  title  retention  or other  similar  agreement,  arrangement,  device  or
restriction;   preemptive  or  similar  right;  any  financing  lease  involving
substantially  the same economic  effect as any of the foregoing;  the filing of
any financing  statement under the Uniform  Commercial Code or comparable law of
any  jurisdiction;  restriction on sale,  transfer,  assignment,  disposition or
other alienation; or any option, equity, claim or right of or obligation to, any
other Person, of whatever kind and character.

         material, materially or materiality for the purposes of this Agreement,
shall, unless specifically stated to the contrary,  be determined without regard
to the fact that various  provisions of this Agreement set forth specific dollar
amounts.


                                       A-7


<PAGE>



         Material Agreement shall mean, with respect to UniSite, any Contractual
Obligation that (a) was not entered into in the ordinary course of business, (b)
was entered  into in the  ordinary  course of business  which (i)  involved  the
purchase,  sale or lease  of  goods  or  materials,  or  purchase  of  services,
aggregating  more than $200,000 during any of the last three fiscal years,  (ii)
is not  terminable on thirty (30) days or less notice  without  penalty or other
payment of less than  $50,000,  or (iii)  involves  the  leasing of space on any
tower of UniSite,  (c) involves a capitalized  lease  obligation or Indebtedness
for Money Borrowed,  (d) is or otherwise  constitutes a written agency,  broker,
dealer,  license,  distributorship,  sales  representative  or  similar  written
agreement,  (e)  accounted  for more than three  percent (3%) of the revenues of
UniSite in any of the last three  fiscal  years or is likely to account for more
than three percent (3%) of revenues of UniSite  during the current  fiscal year,
or (f) is with any Authority.

         MCI  Agreement  shall mean the Amended and  Restated  Site  Sharing and
Master License Agreement between MCI Telecommunications Corporation and UniSite,
dated August 29, 1996.

         Merger  shall  have  the  meaning  given  to it in  the  first  Whereas
paragraph.

         Merger Consideration shall have the meaning given to it in Section 3.1.

         Merger Trust shall have the meaning given to it in Section 3.1.

         Multiemployer  Plan shall mean a Plan which is a  "multiemployer  plan"
within the meaning of Section 4001(a)(3) of ERISA.

         Non-Foreign Ownership Certificate shall have the meaning given to it in
Section 7.2(i).

         Omnipoint  shall  mean  Omnipoint  Communications,   Inc.,  a  Delaware
corporation.

         Omnipoint   Acquisition  shall  mean  the  acquisition  by  UniSite  of
ninety-five  percent  (95%) of the  ownership  interests in up to four  Delaware
limited liability  companies described in Section 4.16 of the UniSite Disclosure
Schedule.

         Omnipoint Agreement shall mean the Build Out Agreement,  dated December
12, 1997, between UniSite and Omnipoint and certain Affiliated corporations,  as
heretofore  amended (a true,  correct and complete copy of which has  heretofore
been delivered by UniSite to ATC),  relating to the  construction  by UniSite of
not less than 300 towers on which Omnipoint and certain Affiliated  corporations
are obligated to lease antennae space.

         Omnipoint Amendment shall mean the amendment to the Omnipoint Agreement
presently  being  negotiated  among  ATC,  UniSite  and  Omnipoint,   containing
substantially  the terms and conditions  set forth in Exhibit H attached  hereto
and made a part hereof.

         Option  Securities shall mean all stock  appreciation  rights,  rights,
options  and  warrants,  and  calls or  commitments  evidencing  the  right,  to
subscribe  for,  purchase  or  otherwise  acquire  shares  of  capital  stock or
Convertible  Securities,  whether or not the right to subscribe for, purchase or
otherwise acquire is immediately  exercisable or is conditioned upon the passage
of time, the occurrence or  non-occurrence  or the existence or non-existence of
some other Event.

         Organic  Document  shall  mean,  with  respect  to a Person  which is a
corporation,  its charter,  its by-laws and all shareholder  agreements,  voting
trusts and similar arrangements applicable to any of its capital stock and, with
respect to a Person which is an Entity other than a  corporation,  its agreement
and  certificate  of

                                       A-8


<PAGE>


partnership, any agreements among partners,  operating agreement,  management or
similar   agreements  or  other  document   governing   formation,   governance,
distributions  or sharing of  profits  and  losses,  including  those  among its
owners.

         PBGC shall mean the Pension Benefit Guaranty Corporation and any Entity
succeeding to any or all of its functions under ERISA.

         Pension Plan shall mean a Plan that is an employee pension benefit plan
as defined in Section 3(2) of ERISA.

         Permitted  Liens shall mean (a) Liens for current Taxes not yet due and
payable,  and (b) such  imperfections  of  title,  easements,  encumbrances  and
mortgages or other Liens, if any, as are not,  individually or in the aggregate,
substantial in character,  amount or extent and do not  materially  detract from
the value, or materially interfere with the present use, of the property subject
thereto or affected thereby,  or otherwise  materially impair the conduct of the
UniSite Business.

         Person shall mean any natural individual or any Entity.

         personal  property shall mean all of the machinery,  equipment,  tools,
vehicles, furniture, leasehold improvements, office equipment, plant, inventory,
spare parts and other  tangible  personal  property which are owned or leased by
UniSite and used or useful as of the date hereof in the conduct of the  business
or operations of the UniSite Business, plus such additions thereto and deletions
therefrom arising in the ordinary course of business between the date hereof and
the Closing Date.

         Plan shall mean,  with respect to any Person and at a particular  time,
any employee  benefit plan as defined in Section 3(3) of ERISA and in respect of
which such Person or an ERISA  Affiliate is (or, if such plan were terminated at
such time,  would under  Section 4069 of ERISA be deemed to be) an "employer" as
defined in Section 3(5) of ERISA.

         Preliminary Merger  Consideration shall have the meaning given to it in
Section 3.5.

         Private Authorizations shall mean all approvals, concessions, consents,
franchises,  licenses,  permits,  and other authorizations of all Persons (other
than   Authorities)   including   without   limitation  those  with  respect  to
intellectual property.

         real property shall mean all of the fee estates and buildings and other
fixtures and improvements  thereon,  leasehold  interest,  easements,  licenses,
rights to access,  rights-of-way,  and other real  property  interest  which are
owned or used by UniSite as of the date hereof, in the operations of the UniSite
Business,  plus such additions  thereto and deletions  therefrom  arising in the
ordinary course of business between the date hereof and the Closing Date.

         Regulations  shall mean the federal income Tax regulations  promulgated
under  the Code,  as such  Regulations  may be  amended  from time to time.  All
references  herein to specific  sections of the Regulations shall be deemed also
to refer to any  corresponding  provisions  of succeeding  Regulations,  and all
references  to  temporary  Regulations  shall  be  deemed  also to  refer to any
corresponding provisions of final Regulations.

         Representatives shall have the meaning given to it in Section 6.1(a).

         Required   Consents  shall  mean  the  obtaining  by  UniSite,   on  an
unconditional basis, of all consents, approvals or other authorizations required
to consummate the Merger and for the Surviving  Corporation to


                                       A-9


<PAGE>



continue to enjoy the benefits of all of the  following  agreements  and leases,
including  that such Merger will not  conflict  with,  and result in a breach or
violation of, or constitute a default under, or permit the  renegotiation of any
term or provision of or the  acceleration  of any obligation or liability in, or
permit the  termination  of, or but for any  requirement  of giving of notice or
passage  of time or both  would  constitute  such a  conflict  with,  breach  or
violation  of,  or  default  under,  or  permit  any  such  acceleration  in  or
termination  of, any of the following  agreements  or leases:  (a) the Omnipoint
Agreement,  (b) the MCI Management Agreement, (c) the USPS Management Agreement,
(d) the GTE Management Agreement, (e) the AT&T Agreement, (g) any other material
management  or site service  agreements,  and (h) any ground  lease  pursuant to
which  UniSite  leases  land  on  which  a  Completed  Tower  or a  tower  under
construction or proposed to be constructed is or will be located.

         Restricted  Transaction  shall mean any (i) acquisition or agreement to
acquire, other than the Omnipoint  Acquisition,  (x) by merging or consolidating
with, or by  purchasing a substantial  portion of the assets of, or by any other
manner,  any business or any Person or other business  organization  or division
thereof or (y) any assets (other than in the ordinary  course of business  which
for purposes of this definition does not include the acquisition or construction
of towers or other  communications  sites and related  assets and other business
involved in the communications sites industry), or (ii) undertaking or agreement
to undertake the construction of one or more communications towers.

         SEC shall mean the Securities and Exchange Commission and shall include
any successor Authority.

         Securities Act shall mean the Securities Act of 1933, and the rules and
regulations  thereunder,  all as from time to time in effect,  or any  successor
law,  rules or  regulations,  and any  reference to any  statutory or regulatory
provision  shall be deemed  to be a  reference  to any  successor  statutory  or
regulatory provision.

         Software shall have the meaning given to it in Section 4.21.

         Structural Reports shall have the meaning given to it in Section 6.15.

         Subsidiary  shall mean,  with respect to a Person,  any  corporation  a
majority of the capital  stock  ordinarily  entitled to vote for the election of
directors of which, or if any Entity other than a corporation, a majority of the
equity  interests  of  which,  is  owned  directly  or  indirectly,  legally  or
beneficially, by such Person or any other Person controlled by such Person.

         Superior Proposal shall mean an Alternative  Transaction that the Board
of  Directors  of  UniSite  determines  in good  faith,  after the advice of and
consultation with legal counsel and UniSite's  independent  financial  advisors,
contains terms and conditions,  including the likelihood of  consummation,  that
are  materially  more  favorable  from a financial  point of view to the UniSite
stockholders than those set forth in this Agreement (as ATC may have proposed to
amend it pursuant to the provisions of Section 6.5(d)).

         Surviving  Corporation  shall have the  meaning  given to it in Section
2.1.

         Tax (and "Taxable",  which shall mean subject to Tax), shall mean, with
respect to any Person,  (a) all taxes (domestic or foreign),  including  without
limitation any income (net, gross or other including  recapture of any Tax items
such as  investment  Tax  credits),  alternative  or add-on  minimum Tax,  gross
income,  gross receipts,  gains,  sales, use, leasing,  lease, user, ad valorem,
transfer, recording, franchise, profits, property (real or personal, tangible or
intangible),  fuel,  license,  withholding on amounts paid to or by such Person,
payroll,  employment,  unemployment,  social security, excise, severance, stamp,
occupation, premium, environmental or windfall profit Tax, custom, duty or other
Tax, or other like  assessment or charge of any kind  whatsoever,  together with
any  interest,  levies,  assessments,  charges,  penalties,  additions to Tax or
additional  amount

                                      A-10


<PAGE>


imposed by any Taxing  Authority,  (b) any joint or  several  liability  of such
Person  with  any  other  Person  for the  payment  of any  amounts  of the type
described  in (a),  and (c) any  liability of such Person for the payment of any
amounts  of the type  described  in (a) as a result of any  express  or  implied
obligation to indemnify any other Person.

         Tax Return or Returns shall mean all returns, consolidated or otherwise
(including without limitation  information  returns),  required to be filed with
any Authority with respect to Taxes.

         Taxing   Authority  shall  mean  any  Authority   responsible  for  the
imposition or collection of any Tax.

         Title Report shall have the meaning given to it in Section 6.7.

         Terminating Party shall have the meaning given to it in Section 8.1(a).

         Termination Date shall have the meaning given to it in Section 8.1(a).

         Termination  Notice  shall  have the  meaning  given  to it in  Section
8.1(a).

         Tower  Construction  Costs shall mean in respect of any tower,  without
duplication  and to the extent not  specifically  recouped from or reimbursed by
the tenant,  the aggregate amount (including  transportation  costs) required to
construct  such tower at a site on which such tower is to be located,  including
all  payments  to  general  contractors,  costs of  zoning,  building  and other
required  permits,  all site  acquisition  and  development  costs and  expenses
(including  for a lighting  system  meeting  the minimum  specifications  of the
Federal Aviation  Administration  and any other  applicable  Authorities and the
obtaining of Environmental Reports and Structural Reports to the extent actually
paid  by  UniSite)  and  other  indirect  costs  typically  allocable  to  tower
construction costs under GAAP;  provided,  however that Tower construction costs
shall not include any financing costs,  expenses and charges,  including without
limitation all capitalized interest, or any capitalized labor costs.

         Towers Under  Construction  shall mean any tower that UniSite is, as of
the Effective Time, in the process of constructing (including without limitation
those with respect to which it is in the process of doing site acquisition work)
and that will, upon  completion,  be owned by it and leased to wireless  service
providers.

         Transactions shall mean the transactions contemplated to be consummated
on or prior to the Closing Date, including without limitation the Merger and the
execution, delivery and performance of the Collateral Documents.

         UniSite shall have the meaning given to it in the Preamble.

         UniSite Assets shall have the meaning given to it in Section 4.4(a) and
shall,  if applicable,  include  without  limitation,  those of all of UniSite's
Subsidiaries.

         UniSite  Business  shall have the meaning given to it in Section 4.4(a)
and shall, if applicable,  include without limitation, those of all of UniSite's
Subsidiaries.

         UniSite  Class A Preferred  Stock shall have the meaning given to it in
Section 3.1.

         UniSite  Class B Preferred  Stock shall have the meaning given to it in
Section 3.1.

         UniSite  Class C Preferred  Stock shall have the meaning given to it in
Section 3.1.

                                      A-11


<PAGE>



         UniSite Common Stock shall have the meaning given to it in Section 3.1.

         UniSite Disclosure  Schedule shall mean the UniSite Disclosure Schedule
to be delivered by UniSite to ATC pursuant to the provisions of Section 10.15.

         UniSite Employees shall have the meaning given to it in Section 4.14.

         UniSite  Financial  Statements  shall have the  meaning  given to it in
Section 4.2.

         UniSite Notes shall have the meaning given to it in Section 6.9.

         UniSite  Preferred  Stock shall have the meaning given to it in Section
3.1.

         UniSite  Security  Agreement  shall  have  the  meaning  given to it in
Section 6.9.

         UniSite Shares shall have the meaning given to it in Section 3.1.

         UniSite Software shall have the meaning given to it in Section 6.12.

         UniSite Stock shall have the meaning given to it in Section 3.1.

         UniSite Stockholder Approval shall have the meaning given it in Section
6.13.

         UniSite  Stockholder Meeting shall have the meaning given it in Section
6.13.

         UniSite Stockholder  Representatives shall have the meaning given to it
in Section 10.14.

         UniSite  Warrants  shall mean the warrants to purchase  UniSite  Common
Stock issued in connection with the sale of UniSite's 13%  Subordinated  Accrual
Notes due December 15, 2004.

         UniSite's  knowledge (or words of similar import) shall mean the actual
knowledge of any UniSite stockholder or any UniSite director or officer, as such
knowledge  exists  on the date of this  Agreement,  after  reasonable  review of
appropriate  UniSite records and after reasonable inquiry of appropriate UniSite
Employees.

         USPS  Agreement  shall mean the Amended and  Restated  Site  Management
Agreement between the United States Postal Service and UniSite,  effective as of
January 4, 1999.

         Working  Capital  shall mean,  with  respect to UniSite,  the amount by
which the  current  assets of UniSite and its  Subsidiaries  exceed (or are less
than) the current  liabilities  (other than the principal amount of Indebtedness
for Money Borrowed) of UniSite and its Subsidiaries, as determined in accordance
with GAAP, consistently applied with the UniSite Financial Statements, except as
hereinafter specifically set forth; provided,  however, that notwithstanding the
foregoing:

         (a) current assets shall be increased by an amount equal to the sum of:

                  (i) Tower  Construction  Costs  actually  paid by UniSite with
         respect to Towers Under Construction;



                                      A-12


<PAGE>


                  (ii) funds  actually  paid to (x) CSFB for acting as financial
         adviser  to  UniSite  with  respect  to  the  subject  matter  of  this
         Agreement,  (y) Fleet,  for acting as  financial  adviser to UniSite in
         connection with its sale of high-yield debt securities in an amount not
         in excess of $500,000  together with  reimbursement of reasonable costs
         and expenses;

                  (iii)  funds  actually  paid with  respect  to all  severance,
         accrued  vacation  or other  benefits  payable  to  terminated  UniSite
         Employees as a result of the Merger  (other than those paid pursuant to
         the  plan  referred  to in  Section  6.14) to the  extent  they do not,
         together  with the amounts  accrued under clause  (b)(i)(z)  following,
         exceed $2,000,000; and

                  (iv) funds actually paid by UniSite  subsequent to the date of
         this  Agreement  and  prior to the  Effective  Time  for  Environmental
         Reports and Structural Reports on Completed Towers.

         (b) There shall be:

                  (i) excluded from current  liabilities any accounts payable or
         accrued expenses incurred:

                           (v)  by  UniSite  subsequent  to  the  date  of  this
                  Agreement  and prior to the Effective  Time for  Environmental
                  Reports and Structural Reports on Completed Towers.

                           (w) in  respect  of  Tower  Construction  Costs  with
                  respect to Towers Under Construction;

                           (x)  subsequent  to the  date  of this  Agreement  in
                  respect   of   acquisitions   of  towers   (so  long  as  such
                  acquisitions  were  approved  by ATC in  accordance  with  the
                  provisions of Section 6.6);

                           (y) in respect  of (I) CSFB for  acting as  financial
                  adviser as  described  above,  and (II)  Fleet,  for acting as
                  financial  adviser  as  described  above in an  amount  not in
                  excess of $500,000 (less any amount theretofore  actually paid
                  and reflected in clause  (a)(iii)(y)  immediately  preceding),
                  together   with,   without   duplication,   reimbursement   of
                  reasonable costs and expenses; and

                           (z) in respect of all severance,  accrued vacation or
                  other benefits payable to terminated  UniSite Employees (other
                  than those paid  pursuant  to the plan  referred to in Section
                  6.14) to the extent they do not,  together  with  amounts paid
                  under clause (a)(iv) above, exceed $2,000,000; and

                  (ii) included in current  liabilities  an accrual with respect
         to the full  amount of all costs and  expenses  required to be borne by
         UniSite pursuant to the provisions of this Agreement, including without
         limitation  (x) those  referred to in Section 10.2 (except  amount paid
         under clause (a)(v) or excluded under clause (b)(i)(u) above),  (y) all
         severance,  accrued  vacation or other  benefits paid or payable (other
         than with  respect  to the plan  referred  to in  Section  6.14) to all
         terminated  UniSite  Employees in excess of $2,000,000,  whether or not
         required by GAAP (it being understood that reserves will be established
         for any such obligation not accounted for as a liability),  and (z) all
         benefits  payable  pursuant to the plan referred to in Section 6.14 (it
         being  understood  that  reserves  will be  established  for  any  such
         obligation not accounted for as a liability);  provided,  however, that
         it is understood, and ATC hereby agrees, that the Surviving Corporation
         shall be responsible  for (A) amounts payable to (I) CSFB for acting as
         financial  adviser as described  above,  and (II) Fleet,  for acting as
         financial  adviser  as  described  above in an amount  not in excess of
         $500,000 together with


                                      A-13


<PAGE>

         reimbursement of reasonable  costs and expenses,  and (B) all severance
         benefits,  accrued  vacation or other  benefits  payable to  terminated
         UniSite  Employees (other than those paid pursuant to the plan referred
         to in Section  6.14) to the extent they do not,  together  with amounts
         paid under clause  (a)(iv)  above or excluded  under  clause  (b)(i)(z)
         above, exceed $2,000,000.


                                      A-14


                     [American Tower Corporation Letterhead]


FOR IMMEDIATE RELEASE

ATC Contact:  Anne Alter, Director of Investor Relations
Telephone:  (617) 375-7500
UNIsite Contact:  Grace Vista, Marketing Manager
Telephone:(813) 915-3511

AMERICAN TOWER CORPORATION ANNOUNCES MERGER WITH UNISITE, INC.

Boston,  Massachusetts  June 28, 1999 American  Tower  Corporation  (NYSE:  AMT)
announced  today that it has entered into an  agreement  to merge with  UNIsite,
Inc.

The cash  transaction is estimated to be valued at  approximately  $205 million,
which is based on UNIsite owning and operating 600 wireless communication towers
at the time of closing.  The purchase  price will be subject to  adjustment  for
closing  date  working  capital  and  includes  American  Towers  assumption  of
approximately   $40  million  of  debt,   subject  to  adjustment   for  interim
acquisitions and capital  expenditures,  and $165 million in cash. The merger is
expected to close by January 31, 2000.

UNIsite was founded in 1994 to address the  challenges  associated  with antenna
siting and to focus  primarily  on tower site  management.  Most  recently,  the
company has expanded its scope to include site  ownership and  development.  The
Company now owns  approximately  400 towers  suited for  co-location  and has an
exclusive build-to-suit contract with Omnipoint through the year 2012.

Jim  Eisenstein,  Chief  Development  Officer  of  American  Tower,  said of the
transaction,  We are very pleased to have  entered  into a merger with  UNIsite.
This  transaction not only adds an attractive  group of towers to our portfolio,
particularly  in the  northeast,  but also gives us an opportunity to expand our
relationship with a number of carriers.

Dan Behuniak,  President of UNIsite,  remarked, re excited to become part of the
American Tower team. As the industry consolidates further,  American Tower, with
its talented management team and financial strength, is clearly slated to be one
of the best places to be.

American  Tower is a  leading  independent  owner,  operator  and  developer  of
broadcast and wireless  communications  sites in the United  States and,  giving
effect to this and other pending transactions,  operates more than 4,000 towers,
including 185 broadcast  tower sites, in 44 states and the District of Columbia.
Based in Boston,  American Tower has a national  footprint with regional hubs in
Boston, Atlanta,  Chicago,  Houston and San Francisco.  Through its wholly owned
subsidiary,  ATC Teleports,  Inc., American Tower also owns and operates, giving
effect to pending transactions,  over 90 satellite antennas in various locations
across the United States.  For more information about American Tower Corporation
and    ATC    Teleports,     please    visit    our    web    sites    HYPERLINK
http://www.americantower.com www.americantower.com and www.atcteleports.com.

This  press  release  contains  forward-looking   statements  concerning  future
expectations,   plans  or  strategies   that  involve  a  number  of  risks  and
uncertainties.  The Company wishes to caution  readers that certain  factors may
have  affected  the  Company's  actual  results  and  could  cause  results  for
subsequent   periods  to  differ   materially   from  those   expressed  in  any
forward-looking  statement  made by or on behalf of the  Company.  Such  factors
include,  but  are not  limited  to (i)  substantial  capital  requirements  and
leverage   principally  as  a  consequence  of  its  ongoing   acquisitions  and
construction activities,  (ii) dependence on demand for wireless communications,
use of satellites for internet data transmission,  and implementation of digital
television,  (iii) the success of the Company's tower  construction  program and
(iv)  the  successful   operational   integration  of  the  Company  s  business
acquisitions.  The Company  undertakes no  obligation to update  forward-looking
statements to reflect subsequently occurring events or circumstances.

                                      ###

- --------------------------------------------------------------------------------
American Tower Corporation    116 Huntington Avenue  Boston, Massachusetts 02116
(617) 375-7500  FAX (617) 375-7575                         www.americantower.com


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