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                          REGISTRATION RIGHTS AGREEMENT




                          Dated as of February 15, 2000


                                      Among


                           AMERICAN TOWER CORPORATION

                                    as Issuer

                                       and


                     CREDIT SUISSE FIRST BOSTON CORPORATION
                          DEUTSCHE BANK SECURITIES INC.
                              LEHMAN BROTHERS INC.
                         BANC OF AMERICA SECURITIES LLC
                            BEAR, STEARNS & CO. INC.
                            SALOMON SMITH BARNEY INC.
                          FIRST UNION SECURITIES, INC.
                              GOLDMAN, SACHS & CO.
                      LEGG MASON WOOD WALKER, INCORPORATED
               MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED
                        MORGAN STANLEY & CO. INCORPORATED
                        RAYMOND JAMES & ASSOCIATES, INC.

                              as Initial Purchasers

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<PAGE>



<TABLE>
<CAPTION>
                                             TABLE OF CONTENTS

                                                                                                      Page

<S>                                                                                                    <C>
1.       Definitions.....................................................................................1

2.       Shelf Registration..............................................................................5

3.       Additional Interest.............................................................................7

4.       Registration Procedures........................................................................10

5.       Registration Expenses..........................................................................20

6.       Indemnification................................................................................22

7.       Rules 144 and 144A.............................................................................26

8.       Underwritten Registrations.....................................................................27

9.       Representations and Warranties.................................................................27

10.      Miscellaneous..................................................................................29
         (a)      No Inconsistent Agreements............................................................29
         (b)      Adjustments Affecting Registrable
                  Securities............................................................................29
         (c)      Amendments and Waivers................................................................30
         (d)      Notices...............................................................................30
         (e)      Successors and Assigns................................................................32
         (f)      Counterparts..........................................................................32
         (g)      Headings..............................................................................32
         (h)      Governing Law.........................................................................32
         (i)      Severability..........................................................................33
         (j)      Securities Held by the Company
                  or Its Affiliates.....................................................................33
         (k)      Third Party Beneficiaries.............................................................33
         (l)      Entire Agreement......................................................................33
</TABLE>




                                                   -i-

<PAGE>



                          REGISTRATION RIGHTS AGREEMENT


         This  Registration  Rights  Agreement (the  "Agreement") is dated as of
February 15, 2000, among American Tower Corporation, a Delaware corporation (the
"Company"), and Credit Suisse First Boston Corporation, Deutsche Bank Securities
Inc., Lehman Brothers Inc., Banc of America  Securities LLC, Bear, Stearns & Co.
Inc., Salomon Smith Barney Inc., First Union Securities,  Inc., Goldman, Sachs &
Co., Legg Mason Wood Walker, Incorporated, Merrill Lynch, Pierce, Fenner & Smith
Incorporated,  Morgan Stanley & Co. Incorporated and Raymond James & Associates,
Inc. (individually, an "Initial Purchaser"; together, the "Initial Purchasers").

         This  Agreement  is  entered  into  in  connection  with  the  Purchase
Agreement,  dated  February  9,  2000,  between  the  Company  and  the  Initial
Purchasers (the "Purchase Agreement"),  which provides for the issuance and sale
by the Company to the Initial Purchasers of the Company's 5.0% Convertible Notes
Due 2010 (the "Convertible Notes"). In order to induce the Initial Purchasers to
enter into the  Purchase  Agreement,  the  Company  has  agreed to  provide  the
registration  rights set forth in this  Agreement for the benefit of the Initial
Purchasers and their direct and indirect  transferees and assigns. The execution
and  delivery  of this  Agreement  is a  condition  to the  Initial  Purchasers'
obligation to purchase the Convertible Notes under the Purchase Agreement.

         The parties hereby agree as follows:

         1.       Definitions.

         As used in this Agreement, the following terms shall have the following
meanings:

         Additional Interest:  See Section 3(a) hereof.

         Advice:  See Section 4 hereof.






<PAGE>



         Agreement: See the first introductory paragraph hereto.

         Amount of Registrable Securities: (a) With respect to Convertible Notes
constituting Registrable Securities,  their aggregate principal amount, (b) with
respect to Underlying Shares constituting Registrable Securities,  the aggregate
number of such Underlying  Shares multiplied by the Conversion Price (as defined
in the Indenture  relating to the Convertible Notes upon the conversion of which
such  Underlying  Shares  were  issued) in effect at the time of  computing  the
Amount  of  Registrable  Securities  or, if no such  Convertible  Notes are then
outstanding,  the last Conversion  Price that was in effect under such Indenture
when any such Convertible Notes were last  outstanding,  and (c) with respect to
combinations  thereof,  the  sum of  (a)and  (b) for  the  relevant  Registrable
Securities.

         Certificate Shares:  See Section 9 hereof.

         Closing Date: A Closing Date as defined in the Purchase Agreement.

         Company:  See the first introductory paragraph hereto.

         Convertible Notes: See the second introductory paragraph hereto.

         Damages Payment Date:  See Section 3(c) hereof.

         Depositary: The Depository Trust Company until a successor is appointed
by the Company.

         Effectiveness Date: The 150th day after the Issue Date.

         Effectiveness Period:  See Section 2 hereof.

         Exchange Act: The Securities Exchange Act of 1934, as amended,  and the
rules and regulations of the SEC promul gated thereunder.




                                       -2-

<PAGE>



         Filing Date: The 90th day after the Issue Date.

         Global Certificate: See Section 9 hereof.

         Holder: Any holder of Registrable Securities.

         Indemnified Person: See Section 6(c) hereof.

         Indemnifying Person:  See Section 6(c) hereof.

         Indenture:  The Indenture,  dated as of February 15, 2000,  between the
Company and The Bank of New York, as Trustee,  pursuant to which the Convertible
Notes are issued, as amended or supplemented from time to time.

         Initial Purchaser: See the first introductory paragraph hereto.

         Initial Purchasers: See the first introductory paragraph hereto.

         Initial Shelf Registration:  See Section 2(a) hereof.

         Inspectors: See Section 4(n) hereof.

         Issue Date: The latest Closing Date on which the Convertible Notes were
issued and sold to the Initial Purchasers pursuant to the Purchase Agreement.

         NASD:  See Section 4(q) hereof.

         Participant:  See Section 6(a) hereof.

         Person:  An individual,  partnership,  corporation,  limited  liability
company,  unincorporated association,  trust or joint venture, or a governmental
agency or political subdivision thereof.

         Prospectus:  The  prospectus  included in any Registra  tion  Statement
(including,  without  limitation,  any  prospectus  subject to completion  and a
prospectus that includes any information previously omitted from a



                                       -3-

<PAGE>



prospectus filed as part of an effective registration statement in reliance upon
Rule 430A  promulgated  under the Securities Act), as amended or supplemented by
any  prospectus  supplement,  and all other  amendments  and  supplements to the
Prospectus,  including post-effective  amendments, and all material incorporated
by reference or deemed to be incorporated by reference in such Prospectus.

         Purchase Agreement: See the second introductory paragraph hereto.

         Records:  See Section 4(n) hereof.

         Registrable Securities: All Convertible Notes and all Underlying Shares
upon original  issuance  thereof and at all times  subsequent  thereto until the
earliest to occur of (i) a  Registration  Statement  covering  such  Convertible
Notes and  Underlying  Shares has been  declared  effective  by the SEC and such
Convertible Notes and Underlying Shares have been disposed of in accordance with
such  effective  Registration   Statement,   (ii)  such  Convertible  Notes  and
Underlying  Shares are sold in  compliance  with Rule 144 or could  (except with
respect to affiliates of the Company within the meaning of the  Securities  Act)
be sold in  compliance  with  paragraph  (k) of such  Rule  144,  or (iii)  such
Convertible Notes and any Underlying Shares cease to be outstanding.

         Registration Default:  See Section 3(a) hereof.

         Registration Statement: Any registration statement of the Company filed
with  the SEC  pursuant  to the  provisions  of this  Agreement,  including  the
Prospectus, amendments and supplements to such registration statement, including
post-  effective  amendments,  all exhibits and all  material  incorpo  rated by
reference  or  deemed  to be  incorporated  by  reference  in such  registration
statement.

         Rule 144: Rule 144  promulgated  under the Securities Act, as such Rule
may be amended from time to time,  or any similar rule (other than Rule 144A) or
regulation  hereafter  adopted  by the SEC  providing  for  offers  and sales of
securities made in compliance therewith resulting in offers



                                       -4-

<PAGE>



and sales by  subsequent  holders that are not  affiliates  of an issuer of such
securities being free of the registration and prospectus  delivery  requirements
of the Securities Act.

         Rule 144A: Rule 144A promulgated under the Securities Act, as such Rule
may be amended  from time to time,  or any similar rule (other than Rule 144) or
regulation hereafter adopted by the SEC.

         Rule 415: Rule 415  promulgated  under the Securities Act, as such Rule
may be amended from time to time,  or any similar rule or  regulation  hereafter
adopted by the SEC.

         SEC:  The Securities and Exchange Commission.

         Securities  Act: The Securities Act of 1933, as amended,  and the rules
and regulations of the SEC promulgated thereunder.

         Shelf Registration:  See Section 2(b) hereof.

         Subsequent Shelf Registration: See Section 2(b) hereof.

         TIA: The Trust  Indenture  Act of 1939,  as amended,  and the rules and
regulations of the SEC promulgated thereunder.

         Trustee:  The Trustee under the Indenture.

         Underlying  Shares:  The shares of the Company's  Class A Common Stock,
par value $.01 per share, issuable upon conversion of the Convertible Notes.

         Underwritten  registration or underwritten  offering: A registration in
which securities of the Company are sold to an underwriter for reoffering to the
public.




                                       -5-

<PAGE>



         2.       Shelf Registration

                           (a)      Shelf  Registration.  The  Company  shall as
                                    promptly as reasonably practicable file with
                                    the  SEC a  Registration  Statement  for  an
                                    offering  to be made on a  continuous  basis
                                    pursuant  to Rule  415  covering  all of the
                                    Registrable  Securities  (the "Initial Shelf
                                    Registration").  The  Company  shall use its
                                    reasonable best efforts to file with the SEC
                                    the Initial Shelf  Registration  on or prior
                                    to  the  Filing  Date.   The  Initial  Shelf
                                    Registration shall be on Form S-3 or another
                                    appropriate form permitting  registration of
                                    such  Registrable  Securities  for resale by
                                    Holders in the manner or manners  designated
                                    by them (including,  without limitation, one
                                    or more underwritten offerings). The Company
                                    shall not permit any  securities  other than
                                    the Registrable Securities to be included in
                                    the  Initial  Shelf   Registration   or  any
                                    Subsequent  Shelf  Registration  (as defined
                                    below). By its execution hereof on behalf of
                                    itself  and the  other  Initial  Purchasers,
                                    Credit Suisse First Boston  Corporation also
                                    hereby  waives on its own  behalf  its right
                                    under  the  Registration  Rights  Agreement,
                                    dated February 4, 1999,  between the Company
                                    and  it,  to  include  any  securities  in a
                                    Registration  Statement  filed  pursuant  to
                                    this Agreement.




                                       -6-

<PAGE>



         The Company shall use its reasonable  best efforts to cause the Initial
Shelf Registration to be declared effective under the Securities Act on or prior
to  the  Effectiveness   Date  and  to  keep  the  Initial  Shelf   Registration
continuously effective under the Securities Act until the date that is 24 months
from the Issue  Date (as it may be  shortened  pursuant  to clause (i) or clause
(ii) immediately following,  the "Effectiveness Period"), or such shorter period
ending when (A) all the shares of Registrable  Securities covered by the Initial
Shelf Registration have been sold in the manner set forth and as contemplated in
the  Initial  Shelf  Registration,  (B) the  date on which  all the  Registrable
Securities  (x) held by persons  who are not  affiliates  of the  Company may be
resold  pursuant  to Rule  144(k)  under the  Securities  Act or (y) cease to be
outstanding,  or  (C) a  Subsequent  Shelf  Registration  covering  all  of  the
Registrable Securities has been declared effective under the Securities Act.

                           (b)      Subsequent  Shelf   Registrations.   If  the
                                    Initial Shelf Registration or any Subsequent
                                    Shelf  Registration  ceases to be  effective
                                    for  any  reason  at  any  time  during  the
                                    Effectiveness  Period (other than because of
                                    the sale of all of the securities registered
                                    thereunder),   the  Company  shall  use  its
                                    reasonable best efforts to obtain the prompt
                                    withdrawal  of  any  order   suspending  the
                                    effectiveness  thereof,  and  in  any  event
                                    shall  within 45 days of such  cessation  of
                                    effectiveness   amend  the   Initial   Shelf
                                    Registration  in  a  manner  to  obtain  the
                                    withdrawal  of  the  order   suspending  the
                                    effectiveness thereof, or file an additional
                                    "shelf"  Registration  Statement pursuant to
                                    Rule  415  covering  all of the  Registrable
                                    Securities     (a


                                      -7-
<PAGE>

                                    "Subsequent  Shelf   Registration").   If  a
                                    Subsequent Shelf  Registration is filed, the
                                    Company  shall  use  its   reasonable   best
                                    efforts  to  cause  the   Subsequent   Shelf
                                    Registration to be declared  effective under
                                    the  Securities  Act as soon as  practicable
                                    after   such   filing   and  to  keep   such
                                    Registration      Statement     continuously
                                    effective   for   the   remainder   of   the
                                    Effectiveness  Period.  As used  herein  the
                                    term "Shelf  Registration" means the Initial
                                    Shelf  Registration and any Subsequent Shelf
                                    Registration.

                           (c)      Supplements  and  Amendments.   The  Company
                                    shall  promptly  supplement  and  amend  the
                                    Shelf Registration if required by the rules,
                                    regulations  or  instructions  applicable to
                                    the  registration  form used for such  Shelf
                                    Registration,  if required by the Securities
                                    Act,  or  if  reasonably  requested  by  the
                                    Holders  of a  majority  of  the  Amount  of
                                    Registrable   Securities   covered  by  such
                                    Registration Statement or by any underwriter
                                    of such Registrable Securities.

         3.       Additional Interest

                           (a)      The Company and the Initial Purchasers agree
                                    that the Holders of  Convertible  Notes will
                                    suffer  damages  if  the  Company  fails  to
                                    fulfill  its  obligations  under  Section  2
                                    hereof and that it would not be  feasible to
                                    ascertain  the extent of such  damages  with
                                    precision.  Accordingly,  the




                                      -8-
<PAGE>

                                    Company   agrees  to  pay,   as   liquidated
                                    damages,    additional   interest   on   the
                                    Registrable     Securities      ("Additional
                                    Interest")   as   follows   if  any  of  the
                                    following  events  occur (each such event in
                                    clauses   (i)   through   (iii)   below,   a
                                    "Registration Default"):

         (i)      If  on  or  prior  to  the  Filing  Date,  the  Initial  Shelf
                  Registration has not been filed with the SEC;

         (ii)     If on or prior to the  Effectiveness  Date,  the Initial Shelf
                  Registration has not been declared effective by the SEC; or

         (iii)    If after the Initial Shelf  Registration is declared effective
                  (A) the Initial  Shelf  Registration  thereafter  ceases to be
                  effective  and a Subsequent  Shelf  Registration  covering the
                  Registrable Securities has not become effective or (B) a Shelf
                  Registration  or the  related  prospectus  ceases to be usable
                  (except as permitted  in Section  3(b)  hereof) in  connection
                  with  resales of  Registrable  Securities  during the  periods
                  specified  herein  because  either  (1) any event  occurs as a
                  result of which the related  prospectus  forming  part of such
                  Shelf  Registration  would  include any untrue  statement of a
                  material fact or omit to state any material fact  necessary to
                  make the statements  therein in the light of the circumstances
                  under which they were made not misleading,  or (2) it shall be
                  necessary to amend such Shelf  Registration  or supplement the
                  related  prospectus,  to comply with the Securities Act or the
                  Exchange Act or the respective rules thereunder.

                  Additional  Interest shall accrue on  outstanding  Convertible
Notes constituting  Registrable Securities over and above the interest set forth
in the title of the




                                      -9-
<PAGE>

Convertible Notes and shall accrue on outstanding Underlying Shares constituting
Registrable  Securities,  in each case from and  including the date on which any
such  Registration  Default  shall occur to but  excluding the date on which all
such Registration  Defaults have been cured, at a rate of 0.50% per annum of the
Amount of such  Registrable  Securities.  The Company  shall  notify the Trustee
within  one  business  day  after  each and every  date on which a  Registration
Default occurs.

                           (b)      A  Registration   Default   referred  to  in
                                    Section  3(a)(iii)(B) hereof shall be deemed
                                    not to have  occurred and be  continuing  in
                                    relation  to the Shelf  Registration  or the
                                    related  prospectus if (i) such Registration
                                    Default has  occurred  solely as a result of
                                    (x) the filing of a post-effective amendment
                                    to such Shelf  Registration  to  incorporate
                                    annual audited  financial  information  with
                                    respect  to the  Company  where  such  post-
                                    effective amendment is not yet effective and
                                    needs to be  declared  effective  to  permit
                                    Holders to use the related prospectus or (y)
                                    other  material  events with  respect to the
                                    Company  that would need to be  described in
                                    such  Shelf   Registration  or  the  related
                                    prospectus  and (ii) in the  case of  clause
                                    (y), the Company is proceeding  promptly and
                                    in good  faith to amend or  supplement  such
                                    Shelf Registration and related prospectus to
                                    describe  such  events;  provided,  however,
                                    that  in  any  case  if  such   Registration
                                    Default  occurs for a  continuous  period in
                                    excess of 30 days, Additional Interest shall
                                    be payable in  accordance  with



                                      -10-
<PAGE>

                                    Section   3(a)  hereof  from  the  day  such
                                    Registration   Default   occurs  until  such
                                    Registration Default is cured.

                           (c)      Any  amount  of   Additional   Interest  due
                                    pursuant  to  clause  (i),  (ii) or (iii) of
                                    Section  3(a) hereof will be payable in cash
                                    on  each   February  15  and  August  15  (a
                                    "Damages  Payment  Date")  to the  Holder to
                                    whom  regular  interest  is  payable on such
                                    Damages   Payment   Date  with   respect  to
                                    Convertible   Notes  that  are   Registrable
                                    Securities  and  to  the  Person  that  is a
                                    registered  Holder  15  days  prior  to such
                                    Damages   Payment   Date  with   respect  to
                                    Underlying   Shares  that  are   Registrable
                                    Securities.   The   amount   of   Additional
                                    Interest for Registrable  Securities will be
                                    determined  by  multiplying  the  applicable
                                    Additional  Interest  rate by the  Amount of
                                    such  Registrable  Securities on the Damages
                                    Payment  Date  following  such  Registration
                                    Default  in  the  case  of  the  first  such
                                    payment of Additional  Interest with respect
                                    to a Registration Default (and thereafter at
                                    the next  succeeding  Damages  Payment  Date
                                    until   the   cure  of   such   Registration
                                    Default),  multiplied  by  a  fraction,  the
                                    numerator  of  which is the  number  of days
                                    such Additional Interest rate was applicable
                                    during such period  (determined on the basis
                                    of a 360-day year comprised of twelve 30-day
                                    months),  and the  denominator  of  which is
                                    360.



                                      -11-
<PAGE>

         4.       Registration Procedures

         In connection with the filing of any Registration Statement pursuant to
Section 2 hereof, the Company shall effect such registrations to permit the sale
of the  securities  covered  thereby in accordance  with the intended  method or
methods of disposition  thereof, and pursuant thereto and in connection with any
Registration Statement filed by the Company hereunder the Company shall:

                           (a)      Prepare  and file  with the SEC prior to the
                                    Filing  Date,  a  Registration  Statement or
                                    Registration  Statements  as  prescribed  by
                                    Section  2  hereof,  and use its  reasonable
                                    best efforts to cause each such Registration
                                    Statement  to become  effective  and  remain
                                    effective  as  provided  herein;   provided,
                                    however,  that the Company  shall furnish to
                                    and  afford the  Holders of the  Registrable
                                    Securities   covered  by  such  Registration
                                    Statement,  their  counsel and the  managing
                                    underwriters,    if   any,   a    reasonable
                                    opportunity  to  review  copies  of all such
                                    documents (including copies of any documents
                                    to be incorporated by reference  therein and
                                    all exhibits  thereto)  proposed to be filed
                                    (in each case where  possible  at least five
                                    business days prior to such filing and where
                                    not possible as promptly as  possible).  The
                                    Company  shall  not  file  any  Registration
                                    Statement  or Pro spectus or any  amendments
                                    or  supplements  thereto if the Holders of a
                                    majority   in  Amount  of  the   Registrable
                                    Securities   covered  by  such



                                      -12-
<PAGE>

                                    Registration  Statement,  their counsel,  or
                                    the  managing  underwriters,  if any,  shall
                                    reasonably object.

                           (b)      Prepare   and   file   with   the  SEC  such
                                    amendments and post-effective  amendments to
                                    each Shelf Registration, as may be necessary
                                    to   keep   such   Registration    Statement
                                    continuously effective for the Effectiveness
                                    Period;  cause the related  Prospectus to be
                                    supplemented  by any  Prospectus  supplement
                                    required  by  applicable   law,  and  as  so
                                    supplemented  to be filed  pursuant  to Rule
                                    424  (or  any  similar  provisions  then  in
                                    force) promulgated under the Securities Act;
                                    and comply with the  provisions  of the Secu
                                    rities Act and the Exchange  Act  applicable
                                    to it with respect to the disposition of all
                                    securities   covered  by  such  Registration
                                    Statement   as  so   amended   or  in   such
                                    Prospectus as so  supplemented.  The Company
                                    shall  be  deemed   not  to  have  used  its
                                    reasonable    best   efforts   to   keep   a
                                    Registration  Statement effective during the
                                    Effectiveness Period if it voluntarily takes
                                    any  action  that  would  result in  selling
                                    Holders   of  the   Registrable   Securities
                                    covered  thereby not being able to sell such
                                    Registrable  Securities  during  that period
                                    unless such action is required by applicable
                                    law or unless the Company complies with this
                                    Agreement,  including without limitation the
                                    provisions  of



                                      -13-
<PAGE>

                                    Section  4(k) hereof and the last  paragraph
                                    of Section 4(t) hereof.

                           (c)      Notify  the  selling  Holders  of  shares of
                                    Registrable  Securities,  their  counsel and
                                    the managing underwriters,  if any, promptly
                                    (but in any event within two business days),
                                    and confirm such notice in writing, (i) when
                                    a Prospectus or any prospectus supplement or
                                    post-effective  amendment  has  been  filed,
                                    and,   with  respect  to  a  Reg   istration
                                    Statement or any  post-effective  amendment,
                                    when the same has become effective under the
                                    Securities  Act  (including in such notice a
                                    written  statement that any Holder may, upon
                                    request,  obtain, at the sole expense of the
                                    Company,   one   conformed   copy   of  such
                                    Registration   Statement  or  post-effective
                                    amendment including financial statements and
                                    schedules,  documents incorporated or deemed
                                    to  be   incorporated   by   reference   and
                                    exhibits),  (ii) (A) of the  receipt  of any
                                    written  comments  by the SEC or its  staff,
                                    (B) of the  request  by the SEC or its staff
                                    for   amendments   or   supplements   to   a
                                    Registration  Statement or a Prospectus,  or
                                    (C) of the  issuance  by the SEC of any stop
                                    order  suspending  the  effectiveness  of  a
                                    Registration   Statement  or  of  any  order
                                    preventing  or  suspending  the  use  of any
                                    preliminary  prospectus or the initiation of
                                    any proceedings  for that purpose,  (iii) if
                                    at any time when a prospectus is required by
                                    the   Securities  Act  to  be  delivered



                                      -14-
<PAGE>

                                    in connection  with sales of the Registrable
                                    Securities    the     representations    and
                                    warranties  of the Company  contained in any
                                    agreement    (including   any   underwriting
                                    agreement),  contemplated  by  Section  4(m)
                                    hereof  cease to be true and  correct in all
                                    material respects,  (iv) of the happening of
                                    any event, the existence of any condition or
                                    any  information  becoming  known that makes
                                    any  statement  made  in  such  Registration
                                    Statement  or  related   Prospectus  or  any
                                    document   incorporated   or  deemed  to  be
                                    incorporated  therein by reference untrue in
                                    any  material  respect or that  requires the
                                    making of any  changes in or  amendments  or
                                    supplements to such Registration  Statement,
                                    Prospectus or documents so that, in the case
                                    of the Registration  Statement,  it will not
                                    contain any untrue  statement  of a material
                                    fact or  omit to  state  any  material  fact
                                    required to be stated  therein or  necessary
                                    to   make   the   statements   therein   not
                                    misleading,  and  that  in the  case  of the
                                    Prospectus,  it will not  contain any untrue
                                    statement  of a  material  fact  or  omit to
                                    state  any  material  fact  required  to  be
                                    stated  therein  or  necessary  to make  the
                                    statements  therein,  in  the  light  of the
                                    circumstances  under  which  they were made,
                                    not  misleading  and  (v) of  the  Company's
                                    determination    that    a    post-effective
                                    amendment to a Registration  Statement would
                                    be appropriate.



                                      -15-
<PAGE>

                           (d)      Use its  reasonable  best efforts to prevent
                                    the  issuance  of any order  suspending  the
                                    effectiveness of a Registration Statement or
                                    of any order  preventing or  suspending  the
                                    use of a  Prospectus  and, if any such order
                                    is  issued,   to  use  its  reasonable  best
                                    efforts to obtain the withdrawal of any such
                                    order at the earliest possible moment.

                           (e)      If requested by the managing  underwriter or
                                    underwriters  (if any),  or the Holders of a
                                    majority   in  Amount  of  the   Registrable
                                    Securities  being sold in connection with an
                                    underwritten    offering,    (i)    promptly
                                    incorporate  in a prospectus  supplement  or
                                    post-effective amendment such information as
                                    the managing underwriter or underwriters (if
                                    any),  such  Holders or  counsel  for any of
                                    them determine is reasonably necessary to be
                                    included  therein,  (ii)  make all  required
                                    filings  of such  prospectus  supplement  or
                                    such  post-effective  amendment  as  soon as
                                    reasonably practicable after the Company has
                                    received  notification  of the matters to be
                                    incorporated in such  prospectus  supplement
                                    or   post-effective   amendment   and  (iii)
                                    supplement   or  make   amendments  to  such
                                    Registration Statement.

                           (f)      Furnish   to   each   selling    Holder   of
                                    Registrable  Securities  and to counsel  and
                                    each  managing  underwriter,  if any, at the
                                    sole



                                      -16-
<PAGE>

                                    expense of the Company,  one conformed  copy
                                    of    the    Registration    Statement    or
                                    Registration     Statements     and     each
                                    post-effective amendment thereto,  including
                                    financial statements and schedules,  and, if
                                    requested,  all  documents  incorporated  or
                                    deemed  to  be   incorporated   therein   by
                                    reference and all exhibits.

                           (g)      Deliver   to   each   selling    Holder   of
                                    Registrable  Securities,   their  respective
                                    counsel,  and the  underwriters,  if any, at
                                    the sole  expense  of the  Company,  as many
                                    copies  of the  Prospectus  (including  each
                                    form of  preliminary  prospectus)  and  each
                                    amendment  or  supplement  thereto  and  any
                                    documents  incorporated by reference therein
                                    as such Persons may reasonably request; and,
                                    subject to the second  paragraph  of Section
                                    4(t) hereof,  the Company hereby consents to
                                    the  use  of  such   Prospectus   and   each
                                    amendment or  supplement  thereto by each of
                                    the   selling    Holders   of    Registrable
                                    Securities and the  underwriters  or agents,
                                    if any, and dealers (if any),  in connection
                                    with   the   offering   and   sale   of  the
                                    Registrable   Securities   covered  by  such
                                    Prospectus  and any  amendment or supplement
                                    thereto.

                           (h)      Prior to any public  offering of Registrable
                                    Securities,   to  use  its  reasonable  best
                                    efforts  to  register  or  qualify,  to  the
                                    extent  required by  applicable  law, and to




                                      -17-
<PAGE>

                                    cooperate   with  the  selling   Holders  of
                                    Registrable    Securities,    the   managing
                                    underwriter  or  underwriters,  if any,  and
                                    their respective  counsel in connection with
                                    the   registration  or   qualification   (or
                                    exemption   from   such    registration   or
                                    qualification)     of    such    Registrable
                                    Securities  or  offer  and  sale  under  the
                                    securities   or  Blue   Sky   laws  of  such
                                    jurisdictions  within the  United  States as
                                    any   selling   Holder,   or  the   managing
                                    underwriter   or   underwriters   reasonably
                                    request;   provided,   however,  that  where
                                    Registrable  Securities  are  offered  other
                                    than through an underwritten  offering,  the
                                    Company   agrees  to  cause  the   Company's
                                    counsel to perform  Blue Sky  investigations
                                    and file  registrations  and  qualifications
                                    required  to  be  filed   pursuant  to  this
                                    Section 4(h); keep each such registration or
                                    qualification   (or   exemption   therefrom)
                                    effective    during    the    period    such
                                    Registration  Statement  is  required  to be
                                    kept effective and do any and all other acts
                                    or things reasonably  necessary or advisable
                                    to   enable   the    disposition   in   such
                                    jurisdictions of the Registrable  Securities
                                    covered  by  the   applicable   Registration
                                    Statement;   provided,   however,  that  the
                                    Company  shall not be required to qualify as
                                    a  foreign   corporation  or  to  execute  a
                                    general consent to service of process in any
                                    jurisdiction  or subject  itself to



                                      -18-
<PAGE>

                                    taxation generally in any jurisdiction.

                           (i)      Cooperate   with  the  selling   Holders  of
                                    Registrable   Securities  and  the  managing
                                    underwriter  or  underwriters,  if  any,  to
                                    facilitate   the  timely   preparation   and
                                    delivery of certificates representing shares
                                    of Registrable  Securities to be sold, which
                                    certificates  shall not bear any restrictive
                                    legends and shall be in a form  eligible for
                                    deposit with The  Depository  Trust Company;
                                    and  enable  such   shares  of   Registrable
                                    Securities to be in such  denominations  and
                                    registered  in such  names  as the  managing
                                    underwriter  or  underwriters,  if  any,  or
                                    Holders may reasonably request.

                           (j)      Use its reasonable best efforts to cause the
                                    Registrable  Securities covered by the Shelf
                                    Registration Statement to be registered with
                                    or  approved  by  such  other   governmental
                                    agencies or  authorities as may be necessary
                                    to enable the  seller or sellers  thereof or
                                    the underwriter or underwriters,  if any, to
                                    consummate    the    disposition   of   such
                                    Registrable  Securities,  except  as  may be
                                    required  solely  as a  consequence  of  the
                                    nature of such selling Holder's business, in
                                    which case the Company will cooperate in all
                                    reasonable  respects with the filing of such
                                    Registration  Statement  and the granting of
                                    such approvals.



                                      -19-
<PAGE>

                           (k)      Upon   the    occurrence    of   any   event
                                    contemplated   by   paragraph   4(c)(ii)(C),
                                    4(c)(iv) or 4(c)(v)  hereof,  as promptly as
                                    practicable  prepare and (subject to Section
                                    4(a)  hereof) file with the SEC, at the sole
                                    expense  of the  Company,  a  supplement  or
                                    post-effective amendment to the Registration
                                    Statement  or a  supplement  to the  related
                                    Prospectus or any document  incorporated  or
                                    deemed  to  be   incorporated   therein   by
                                    reference,   or  file  any  other   required
                                    document so that, as thereafter delivered to
                                    the purchasers of the Registrable Securities
                                    being sold  thereunder,  any such Prospectus
                                    will not  contain an untrue  statement  of a
                                    material  fact or omit to  state a  material
                                    fact  required  to  be  stated   therein  or
                                    necessary to make the statements therein, in
                                    the light of the  circumstances  under which
                                    they were made,  not  misleading;  provided,
                                    however,   that  the   Company   may   delay
                                    preparing,  filing and distributing any such
                                    supplement  or amendment  (and  continue the
                                    suspension of the use of the  Prospectus) if
                                    the  Company  determines  in good faith that
                                    such  supplement or amendment  would, in the
                                    reasonable  judgment  of  the  Company,  (i)
                                    interfere with or affect the  negotiation or
                                    completion  of a  transaction  that is being
                                    contemplated by the Company  (whether or not
                                    a final  decision has been made to undertake
                                    such transaction) or (ii) involve initial or
                                    continuing  disclosure



                                      -20-
<PAGE>

                                    obligations   that   are  not  in  the  best
                                    interests of the Company's  shareholders  at
                                    such time; provided,  further,  that neither
                                    such delay nor such  suspension with respect
                                    to all  matters  in clause (i) or (ii) shall
                                    extend  for a period of more than 30 days in
                                    any three-month  period or more than 90 days
                                    for all  such  periods  in any  twelve-month
                                    period and shall not  affect  the  Company's
                                    obligation  to pay  Additional  Interest  as
                                    contemplated in Section 3.

                           (l)      Prior  to the  effective  date of the  first
                                    Regis  tration  Statement  relating  to  the
                                    Registrable  Securities,   (i)  provide  the
                                    Trustee  with  certificates  for  the  Regis
                                    trable  Securities  in a form  eligible  for
                                    deposit with The  Depository  Trust  Company
                                    and  (ii)  provide  a CUSIP  number  for the
                                    Registrable Securities.

                           (m)      In connection with any underwritten offering
                                    of  Registrable  Securities  pursuant  to  a
                                    Shelf    Registration,    enter    into   an
                                    underwriting  agreement  as is  customary in
                                    underwritten offerings of securities similar
                                    to the  Registrable  Securities and take all
                                    such  other   actions   as  are   reasonably
                                    requested  by the  managing  underwriter  or
                                    underwriters;   in  order  to   expedite  or
                                    facilitate   the    registration    or   the
                                    disposition of such  Registrable  Securities
                                    and,  in  such  connection,  (i)  make  such
                                    representations   and



                                      -21-
<PAGE>

                                    warranties  to,  and  covenants   with,  the
                                    underwriters with respect to the business of
                                    the Company and its subsidiaries  (including
                                    any acquired business, properties or entity,
                                    if   applicable)   and   the    Registration
                                    Statement, Prospectus and documents, if any,
                                    incorporated or deemed to be incorporated by
                                    reference  therein,  in  each  case,  as are
                                    customarily  made by issuers to underwriters
                                    in  underwritten   offerings  of  securities
                                    similar to the  Registrable  Securities  and
                                    confirm  the  same in  writing  if and  when
                                    requested;  (ii) obtain the written  opinion
                                    of  counsel  to  the   Company  and  written
                                    updates thereof in form, scope and substance
                                    reasonably   satisfactory  to  the  managing
                                    underwriter  or  underwriters,  addressed to
                                    the   underwriters   covering   the  matters
                                    customarily covered in opinions requested in
                                    underwritten offerings of securities similar
                                    to the Registrable Securities and such other
                                    matters as may be  reasonably  requested  by
                                    the managing  underwriter  or  underwriters;
                                    (iii)  obtain  "cold  comfort"  letters  and
                                    updates thereof in form, scope and substance
                                    reasonably   satisfactory  to  the  managing
                                    underwriter   or   underwriters   from   the
                                    independent  certified public accountants of
                                    the Company (and,  if  necessary,  any other
                                    independent  certified public accountants of
                                    any  subsidiary  of  the  Company  or of any
                                    business  acquired  by the Company for which
                                    financial statements and financial



                                      -22-
<PAGE>

                                    data are, or are required to be, included or
                                    incorporated    by    reference    in    the
                                    Registration  Statement),  addressed to each
                                    of the  underwriters,  such letters to be in
                                    customary  form and covering  matters of the
                                    type  customarily  covered in "cold comfort"
                                    letters  in con  nection  with  underwritten
                                    offerings  of  securities   similar  to  the
                                    Registrable   Securities   and  such   other
                                    matters  as  reasonably   requested  by  the
                                    managing  underwriter or  underwriters;  and
                                    (iv) if an underwriting agreement is entered
                                    into, the same shall contain indemnification
                                    provisions  and procedures no less favorable
                                    than those set forth in Section 6 hereof (or
                                    such   other   provisions   and   procedures
                                    acceptable  to  Holders  of  a  majority  in
                                    Amount of Registrable  Securities covered by
                                    such Registration Statement and the managing
                                    underwriter or  underwriters or agents) with
                                    respect  to all  parties  to be  indemnified
                                    pursuant to said Section. The above shall be
                                    done at each closing under such underwriting
                                    agreement,  or as and to the extent required
                                    thereunder.

                           (n)      Make available for inspection by any selling
                                    Holder of such Registrable  Securities being
                                    sold, any underwriter  participating  in any
                                    such disposition of Registrable  Securities,
                                    if any,  and  any  attorney,  accountant  or
                                    other  agent  retained  by any such  selling




                                      -23-
<PAGE>

                                    Holder,  or underwriter  (collectively,  the
                                    "Inspectors"), at the offices where normally
                                    kept,  during  reasonable  business hours at
                                    such  time or times  as  shall  be  mutually
                                    convenient   for   the   Company   and   the
                                    Inspectors  as a group,  all  financial  and
                                    other records, pertinent corporate documents
                                    and  instruments  of  the  Company  and  its
                                    subsidiaries  (collectively,  the "Records")
                                    as shall be  reasonably  necessary to enable
                                    them  to   exercise   any   applicable   due
                                    diligence  responsibilities,  and  cause the
                                    officers,  directors  and  employees  of the
                                    Company and its  subsidiaries  to supply all
                                    information reasonably requested by any such
                                    Inspector    in    connection    with   such
                                    Registration  Statement.  Records  that  the
                                    Company  determines,  in good  faith,  to be
                                    confidential   and  any   Records   that  it
                                    notifies  the  Inspectors  are  confidential
                                    shall  not be  disclosed  by  any  Inspector
                                    unless (i) the disclosure of such Records is
                                    necessary  to avoid or  correct  a  material
                                    misstatement  or  material  omission in such
                                    Registration Statement,  (ii) the release of
                                    such  Records  is  ordered   pursuant  to  a
                                    subpoena  or  other  order  from a court  of
                                    competent jurisdiction,  (iii) disclosure of
                                    such  information  is,  in  the  opinion  of
                                    counsel  for  any  Inspector,  necessary  or
                                    advisable  in  connection  with any  action,
                                    claim,   suit   or   proceeding,   directly,
                                    involving  or  potentially   involving



                                      -24-
<PAGE>

                                    such  Inspector  and arising  out of,  based
                                    upon,   relating  to,  or   involving   this
                                    Agreement or any  transactions  contemplated
                                    hereby  or  arising  hereunder  or (iv)  the
                                    information  in such  Records  has been made
                                    generally available to the public other than
                                    through  the  acts of such  Inspector.  Each
                                    selling    Holder   of   such    Registrable
                                    Securities  will be  required  to agree that
                                    information  obtained  by it as a result  of
                                    such    inspections    shall    be    deemed
                                    confidential  and shall not be used by it as
                                    the basis for any market transactions in the
                                    securities  of the Company  unless and until
                                    such  information is generally  available to
                                    the  public.  Each  selling  Holder  of such
                                    Registrable  Securities  will be required to
                                    further  agree that it will,  upon  learning
                                    that disclosure of such Records is sought in
                                    a  court  of  competent  jurisdiction,  give
                                    notice to the  Company and allow the Company
                                    to undertake  appropriate  action to prevent
                                    disclosure    of    the    Records    deemed
                                    confidential at the Company's sole expense.

                           (o)      Provide (i) the  Holders of the  Registrable
                                    Securities    to   be   included   in   such
                                    registration statement and not more than one
                                    counsel   for  all  the   Holders   of  such
                                    Registrable     Securities,     (ii)     the
                                    underwriters  (which  term,  for purposes of
                                    this Registration  Rights  Agreement,  shall
                                    include a person deemed to be an underwriter



                                      -25-
<PAGE>

                                    within the  meaning of Section  2(11) of the
                                    Securities Act), if any, thereof,  (iii) the
                                    sales or placement  agent, if any,  thereof,
                                    and (iv) one counsel  for such  underwriters
                                    or   agents,   reasonable   opportunity   to
                                    participate  in  the   preparation  of  such
                                    registration   statement,   each  prospectus
                                    included  therein or filed with the SEC, and
                                    each amendment or supplement thereto.

                           (p)      Comply   with  all   applicable   rules  and
                                    regulations  of the SEC and  make  generally
                                    available  to  its  securityholders  earning
                                    statements   satisfying  the  provisions  of
                                    Section 11(a) of the Securities Act and Rule
                                    158   thereunder   (or  any   similar   rule
                                    promulgated  under  the  Securities  Act) no
                                    later  than  45  days  after  the end of any
                                    12-month period (or 90 days after the end of
                                    any  12-month  period  if such  period  is a
                                    fiscal  year) (i)  commencing  at the end of
                                    any  fiscal  quarter  in  which  Registrable
                                    Securities  are  sold to  underwriters  in a
                                    firm commitment or best efforts underwritten
                                    offering   and   (ii)   if   not   sold   to
                                    underwriters in such an offering, commencing
                                    on the first day of the first fiscal quarter
                                    of the Company after the effective date of a
                                    Registration  Statement,   which  statements
                                    shall cover said 12-month periods.

                           (q)      Cooperate  with each  seller of  Registrable
                                    Securities   covered  by  any   Registration
                                    Statement  and  each



                                      -26-
<PAGE>

                                    underwriter,  if any,  participating  in the
                                    disposition of such  Registrable  Securities
                                    and their  respective  counsel in connection
                                    with any  filings  required  to be made with
                                    the  National   Association   of  Securities
                                    Dealers, Inc. (the "NASD"), including if the
                                    Rules of Fair  Practice  and the By- Laws of
                                    the  NASD  or  any  successor  thereto,   as
                                    amended   from   time  to  time   (including
                                    Schedule E thereto) so  require,  engaging a
                                    "qualified independent  underwriter" ("QIU")
                                    as  contemplated  therein and making Records
                                    available  to such QIU as  though  it were a
                                    participating  underwriter  for the purposes
                                    of Section 4(n) and  otherwise  applying the
                                    provisions  of this  Agreement  to such  QIU
                                    (including  indemnification)  as  though  it
                                    were a participating underwriter.

                           (r)      Cause the  Indenture to be  qualified  under
                                    the TIA not later than the effective date of
                                    the first Registration Statement relating to
                                    the   Registrable    Securities;    and   in
                                    connection  therewith,  cooperate  with  the
                                    Trustee and the  Holders of the  Registrable
                                    Securities  to effect  such  changes  to the
                                    Indenture   as  may  be  required   for  the
                                    Indenture to be so  qualified in  accordance
                                    with the terms of the TIA; and execute,  and
                                    use its reasonable best efforts to cause the
                                    Trustee to execute,  all documents as may be
                                    required  to effect  such  changes,  and all
                                    other  forms and  documents



                                      -27-
<PAGE>

                                    required  to be filed with the SEC to enable
                                    the Indenture to be so qualified in a timely
                                    manner.

                           (s)      Use its reasonable best efforts to cause the
                                    Registrable    Securities   covered   by   a
                                    Registration Statement, to be rated with the
                                    appropriate rating agencies, if so requested
                                    by the  Holders of a  majority  in Amount of
                                    Registrable   Securities   covered  by  such
                                    Registration   Statement,  or  the  managing
                                    underwriter or underwriters, if any.

                           (t)      Use its reasonable  best efforts to take all
                                    other steps necessary or advisable to effect
                                    the    registration   of   the   Registrable
                                    Securities   covered   by   a   Registration
                                    Statement contemplated hereby.

         The Company may require  each seller of  Registrable  Securities  as to
which  any  registration  is being  effected  to  furnish  to the  Company  such
information  regarding  such  seller and the  distribution  of such  Registrable
Securities  as the Company  may,  from time to time,  reasonably  request to the
extent necessary or advisable to comply with the Securities Act. The Company may
exclude from such  registration  the  Registrable  Securities  of any seller who
unreasonably  fails to furnish such  information  within a reasonable time after
receiving such request.  Each seller as to which any Shelf Registration is being
effected agrees to furnish  promptly to the Company all information  required to
be  disclosed  in order  to make the  information  previously  furnished  to the
Company  by such  seller  not  materially  misleading  or to omit to  state  any
material fact required to be stated  therein or necessary to make the statements
therein not misleading in light of the circumstances under which they were made.



                                      -28-
<PAGE>

         Each Holder of  Registrable  Securities  agrees by  acquisition of such
Registrable  Securities that, upon actual receipt of any notice from the Company
of the  happening  of any event of the kind  described  in Section  4(c)(ii)(C),
4(c)(iv) or 4(c)(v) hereof, such Holder will forthwith  discontinue  disposition
of such  Registrable  Securities  covered  by  such  Registration  Statement  or
Prospectus  until such  Holder's  receipt of the copies of the  supplemented  or
amended  Prospectus  contemplated by Section 4(k) hereof, or until it is advised
in  writing  (the  "Advice")  by the  Company  that  the  use of the  applicable
Prospectus  may be  resumed,  and  has  received  copies  of any  amendments  or
supplements thereto.

         5.       Registration Expenses

                           (a)      All  fees  and  expenses   incident  to  the
                                    performance  of  or  compliance   with  this
                                    Agreement  by the Company  shall be borne by
                                    the   Company   whether   or  not  a   Shelf
                                    Registration is filed or becomes  effective,
                                    including,   without  limitation,   (i)  all
                                    registration  and  filing  fees  (including,
                                    without limitation, (A) fees with respect to
                                    filings required to be made with the NASD in
                                    connection with an underwritten offering and
                                    (B) fees and  expenses  of  compliance  with
                                    state    securities   or   Blue   Sky   laws
                                    (including,  without limitation,  reasonable
                                    fees  and   disbursements   of   counsel  in
                                    connection with Blue Sky  qualifications  of
                                    the Registrable Securities and determination
                                    of  the   eligibility  of  the   Registrable
                                    Securities for investment  under the laws of
                                    such  jurisdictions  as  provided in Section
                                    4(h)  hereof,  in the  case  of  Registrable
                                    Securities),    (ii)   printing



                                      -29-
<PAGE>

                                    expenses,   including,  without  limitation,
                                    expenses   of  printing   certificates   for
                                    Registrable  Securities  in a form  eligible
                                    for  deposit  with  The   Depository   Trust
                                    Company and of printing  prospectuses if the
                                    printing of prospectuses is requested by the
                                    managing  underwriter  or  underwriters,  if
                                    any,  by the Holders of a majority of shares
                                    of the  Registrable  Securities  included in
                                    any Registration Statement, (iii) messenger,
                                    telephone and delivery  expenses,  (iv) fees
                                    and disbursements of counsel for the Company
                                    and  fees  and   disbursements   of  special
                                    counsel  for  the  sellers  of   Registrable
                                    Securities  (subject  to the  provisions  of
                                    Section   5(b)   hereof),   (v)   fees   and
                                    disbursements  of all independent  certified
                                    public  accountants  referred  to in Section
                                    4(m)(iii)   hereof    (including,    without
                                    limitation,  the  expenses  of  any  special
                                    audit and "cold comfort" letters required by
                                    or  incident  to  such  performance),   (vi)
                                    rating  agency fees,  (vii)  Securities  Act
                                    liability insurance,  if the Company desires
                                    such insurance,  (viii) fees and expenses of
                                    all other  Persons  retained by the Company,
                                    (ix)   internal   expenses  of  the  Company
                                    (including, without limitation, all salaries
                                    and  expenses of officers  and  employees of
                                    the Company  performing  legal or accounting
                                    duties),  (x)  the  expense  of  any  annual
                                    audit,  (xi) the fees and expenses  incurred
                                    in  connection   with  the  listing  of  the
                                    securities



                                      -30-
<PAGE>

                                    to be registered on any securities exchange,
                                    if   applicable,   and  (xii)  the  expenses
                                    relating to printing,  word  processing  and
                                    distributing  all  Registration  Statements,
                                    underwriting  agreements,  securities  sales
                                    agreements,   indentures   and   any   other
                                    documents  necessary in order to comply with
                                    this Agreement.

                           (b)      The Company  shall  reimburse the Holders of
                                    the Registrable  Securities being registered
                                    in a Shelf Regis tration for the  reasonable
                                    fees and  disbursements of not more than one
                                    counsel (in  addition to  appropriate  local
                                    counsel) chosen by the Holders of a majority
                                    in Amount of the  Registrable  Securities to
                                    be included in such  Registration  Statement
                                    and other reasonable  out-of-pocket expenses
                                    of such  Holders of  Registrable  Securities
                                    incurred in connection with the registration
                                    and  sale  of  the  Registrable   Securities
                                    pursuant to any Registration Statement.

         6.       Indemnification

                           (a)      The Company will indemnify and hold harmless
                                    each Holder of Registrable Securities,  each
                                    Person that  participates  as an underwriter
                                    or   sales   agent   in  any  sale  of  such
                                    Registrable      Securities      (each     a
                                    "Participant")  against any losses,  claims,
                                    damages or liabilities, joint or several, to
                                    which such  Participant  may become subject,




                                      -31-
<PAGE>

                                    under the Securities Act or the Exchange Act
                                    or   otherwise,   insofar  as  such  losses,
                                    claims,  damages or liabilities  (or actions
                                    in  respect  thereof)  arise  out  of or are
                                    based upon any untrue  statement  or alleged
                                    untrue   statement  of  any  material   fact
                                    contained in any  Registration  Statement or
                                    Prospectus,  or any  amendment or supplement
                                    thereto   or   any    related    preliminary
                                    prospectus or arise out of or are based upon
                                    the  omission  or alleged  omission to state
                                    therein a material  fact  necessary in order
                                    to make the statements therein, in the light
                                    of the  circumstances  under which they were
                                    made,  not  misleading,  and will  reimburse
                                    each   Purchaser  for  any  legal  or  other
                                    expenses   reasonably   incurred   by   such
                                    Purchaser in connection  with  investigating
                                    or defending any such loss,  claim,  damage,
                                    liability  or  action as such  expenses  are
                                    incurred;   provided,   however,   that  the
                                    Company  will not be liable in any such case
                                    to the  extent  that any such  loss,  claim,
                                    damage  or  liability  arises  out  of or is
                                    based  upon an untrue  statement  or alleged
                                    untrue  statement  in or omission or alleged
                                    omission  from  any  of  such  documents  in
                                    reliance upon and in conformity with written
                                    information  furnished to the Company by any
                                    Participant  specifically  for use  therein;
                                    provided, further, that the Company will not
                                    be  liable  if  such  untrue   statement  or
                                    omission  or  alleged  untrue  statement  or
                                    omission  was



                                      -32-
<PAGE>

                                    contained   or  made   in  any   preliminary
                                    prospectus  and corrected in the  Prospectus
                                    or any amendment or  supplement  thereto and
                                    the  Prospectus  does not  contain any other
                                    untrue  statement  or  omission  or  alleged
                                    untrue  statement  or omission of a material
                                    fact  that  was the  subject  matter  of the
                                    related   proceeding   and  any  such  loss,
                                    liability, claim, damage or expense suffered
                                    or  incurred  by the  Participants  resulted
                                    from any action, claim or suit by any Person
                                    who purchased Registrable Securities that is
                                    the subject  thereof  from such  Participant
                                    and  it  is   established   in  the  related
                                    proceeding that such  Participant  failed to
                                    deliver or provide a copy of the  Prospectus
                                    (as amended or  supplemented) to such Person
                                    with or  prior  to the  confirmation  of the
                                    sale of such Registrable  Securities sold to
                                    such Person if required by  applicable  law,
                                    unless such  failure to deliver or provide a
                                    copy  of  the   Prospectus  (as  amended  or
                                    supplemented)  was a result of noncompliance
                                    by  the  Company  with  Section  4  of  this
                                    Agreement.

                           (b)      The Company may  require,  as a condition to
                                    including  Registrable   Securities  in  any
                                    Registration  Statement,  that  the  related
                                    Participants agree severally and not jointly
                                    to indemnify  and hold  harmless the Company
                                    against  any  losses,   claims,  damages  or
                                    liabilities  to which the Company may become
                                    subject,  under  the



                                      -33-
<PAGE>

                                    Securities   Act  or  the  Exchange  Act  or
                                    otherwise,  insofar as such losses,  claims,
                                    damages  or   liabilities   (or  actions  in
                                    respect  thereof)  arise out of or are based
                                    upon any untrue  statement or alleged untrue
                                    statement of any material fact  contained in
                                    any Registration Statement or Prospectus, or
                                    any amendment or supplement  thereto, or any
                                    related  prospectus,  or arise out of or are
                                    based  upon  the  omission  or  the  alleged
                                    omission  to state  therein a material  fact
                                    necessary  in order  to make the  statements
                                    therein,  in the light of the  circumstances
                                    under which they were made, not  misleading,
                                    in each case to the extent,  but only to the
                                    extent,   that  such  untrue   statement  or
                                    alleged  untrue  statement  or  omission  or
                                    alleged  omission was made in reliance  upon
                                    and in conformity  with written  information
                                    furnished to the Company by such Participant
                                    specifically  for  use  therein,   and  will
                                    reimburse   any  legal  or  other   expenses
                                    reasonably   incurred   by  the  Company  in
                                    connection with  investigating  or defending
                                    any such loss, claim,  damage,  liability or
                                    action as such  expenses are  incurred.  The
                                    liability  of  any  Participant  under  this
                                    subsection  shall in no event exceed the net
                                    proceeds  received by such  Participant from
                                    sales of Registrable  Securities giving rise
                                    to such obligations.



                                      -34-
<PAGE>

                           (c)      Promptly  after  receipt  by an  indemnified
                                    party  under  this  Section of notice of the
                                    commencement of any action, such indemnified
                                    party will, if a claim in respect thereof is
                                    to be made  against the  indemnifying  party
                                    under  subsection  (a) or (b) above,  notify
                                    the  indemnifying  party of the commencement
                                    thereof;  but the  omission so to notify the
                                    indemnifying  party will not relieve it from
                                    any  liability  which  it  may  have  to any
                                    indemnified  party  other  wise  than  under
                                    subsection  (a) or (b)  above.  In case  any
                                    such   action   is   brought   against   any
                                    indemnified   party  and  it  notifies   the
                                    indemnifying   party  of  the   commencement
                                    thereof,  the  indemnifying  party  will  be
                                    entitled to participate  therein and, to the
                                    extent  that it may wish,  jointly  with any
                                    other indemnifying party similarly notified,
                                    to assume the defense thereof,  with counsel
                                    satisfactory to such indemnified  party (who
                                    shall not,  except  with the  consent of the
                                    indemnified   party,   be   counsel  to  the
                                    indemnifying  party),  and after notice from
                                    the  indemnifying  party to such indemnified
                                    party  of  its  election  so to  assume  the
                                    defense thereof, the indemnifying party will
                                    not be  liable  to  such  indemnified  party
                                    under  this  Section  for any legal or other
                                    expenses   subsequently   incurred  by  such
                                    indemnified  party  in  connection  with the
                                    defense thereof other than reasonable  costs
                                    of



                                      -35-
<PAGE>

                                    investigation.  No indemnifying party shall,
                                    without  the prior  written  consent  of the
                                    indemnified party,  effect any settlement of
                                    any pending or threatened  action in respect
                                    of which any  indemnified  party is or could
                                    have been a party and  indemnity  could have
                                    been sought  hereunder  by such  indemnified
                                    party  unless  such  settlement  includes an
                                    unconditional  release  of such  indemnified
                                    party from all  liability on any claims that
                                    are the subject matter of such action.

                           (d)      If the indemnification  provided for in this
                                    Section is  unavailable or  insufficient  to
                                    hold  harmless  an  indemnified  party under
                                    subsection  (a)  or  (b)  above,  then  each
                                    indemnifying  party shall  contribute to the
                                    amount  paid or payable by such  indemnified
                                    party as a  result  of the  losses,  claims,
                                    damages  or   liabilities   referred  to  in
                                    subsection  (a) or  (b)  above  (i) in  such
                                    proportion as is  appropriate to reflect the
                                    relative benefits received by the Company on
                                    the one  hand  and the  Participants  on the
                                    other from the  offering of the  Registrable
                                    Securities   or  (ii)   if  the   allocation
                                    provided   by   clause   (i)  above  is  not
                                    permitted   by   applicable   law,  in  such
                                    proportion as is  appropriate to reflect not
                                    only the  relative  benefits  referred to in
                                    clause (i) above but also the relative fault
                                    of the  Company  on the  one  hand  and  the
                                    Participants on the other in connection with



                                      -36-
<PAGE>

                                    the  statements or omissions  which resulted
                                    in   such   losses,   claims,   damages   or
                                    liabilities  as well as any  other  relevant
                                    equitable   considerations.   The   relative
                                    benefits  received by the Company on the one
                                    hand and any  Participant on the other shall
                                    be  deemed to be in the same  proportion  as
                                    the  total  net  proceeds  from the  initial
                                    offering  of  the   Registrable   Securities
                                    (before deducting  expenses) received by the
                                    Company  bear  to  the  total  net  proceeds
                                    received by such  Participant  from sales of
                                    Registrable  Securities  giving rise to such
                                    obligations.  The  relative  fault  shall be
                                    determined  by  reference  to,  among  other
                                    things, whether the untrue or alleged untrue
                                    statement of a material fact or the omission
                                    or alleged omission to state a material fact
                                    relates  to  information   supplied  by  the
                                    Company or such Participant and the parties'
                                    relative   intent,   knowledge,   access  to
                                    information  and  opportunity  to correct or
                                    prevent  such untrue  statement or omission.
                                    The amount paid by an indemnified party as a
                                    result of the  losses,  claims,  damages  or
                                    liabilities   referred   to  in  the   first
                                    sentence  of this  subsection  (d)  shall be
                                    deemed  to   include   any  legal  or  other
                                    expenses   reasonably   incurred   by   such
                                    indemnified   party   in   connection   with
                                    investigating  or  defending  any  action or
                                    claim   which   is  the   subject   of  this
                                    subsection    (d).    Notwithstanding    the
                                    provisions



                                      -37-
<PAGE>

                           of       this subsection (d), no Participant shall be
                                    required to contribute  any amount in excess
                                    of the  amount  by  which  the net  proceeds
                                    received by such  Participant  from sales of
                                    Registrable Securities exceeds the amount of
                                    any  damages  which  such   Participant  has
                                    otherwise  been required to pay by reason of
                                    such untrue or alleged  untrue  statement or
                                    omission  or  alleged  omission.  No  person
                                    guilty   of   fraudulent   misrepresentation
                                    (within the meaning of Section  11(f) of the
                                    Act) shall be entitled to contribution  from
                                    any  person  who  was  not  guilty  of  such
                                    fraudulent      misrepresentation.       The
                                    Participants' obligations in this subsection
                                    (d) to contribute  are several in proportion
                                    to their  respective  Amounts of Registrable
                                    Securities   registered   pursuant  to  this
                                    Agreement, and not joint.

                           (e)      The  obligations  of the Company  under this
                                    Section   shall  be  in   addition   to  any
                                    liability  which the Company  may  otherwise
                                    have and shall  extend,  upon the same terms
                                    and  conditions,  to each officer,  director
                                    and partner of each  Participant and to each
                                    Person, if any, who controls any Participant
                                    within the meaning of the  Securities Act or
                                    the Exchange Act; and the obligations of the
                                    Participant  under this Section  shall be in
                                    addition   to  any   liability   which   the
                                    respective  Participants  otherwise have and
                                    shall  extend,   upon  the



                                      -38-
<PAGE>

                                    same terms and  conditions,  to each officer
                                    and  director  of the  Company  and to  each
                                    Person,  if any,  who  controls  the Company
                                    within the meaning of the  Securities Act or
                                    the Exchange Act.

         7.       Rules 144 and 144A.

         The  Company  covenants  that it will file the  reports  required to be
filed by it under  the  Securities  Act and the  Exchange  Act and the rules and
regulations  adopted by the SEC thereunder in a timely manner in accordance with
the  requirements  of the Securities Act and the Exchange Act and such rules and
regulations  and,  if at any time  the  Company  is not  required  to file  such
reports, it will, upon the request of any Holder of Registrable Securities, make
publicly  available  annual  reports and such  information,  documents and other
reports of the type  specified in Sections 13 and 15(d) of the Exchange Act. The
Company  further  covenants  for so long as any  Registrable  Securities  remain
outstanding,  to make available to any Holder or beneficial owner of Registrable
Securities in connection with any sale thereof and any prospective  purchaser of
such  Registrable   Securities  from  such  Holder  or  beneficial   owner,  the
information  required by Rule  144A(d)(4)  under the  Securities Act in order to
permit resales of such Registrable Securities pursuant to Rule 144A.

         8.       Underwritten Registrations.

         If any of the Registrable  Securities covered by any Shelf Registration
is to be sold in an underwritten  offer ing, the investment banker or investment
bankers and manager or managers  that will manage the offering  will be selected
by the Holders of a majority in Amount of such Registrable  Securities  included
in such offering and reasonably acceptable to the Company.

         No Holder of Registrable Securities may participate in any underwritten
registration  hereunder  unless  such  Holder (a)  agrees to sell such  Holder's
Registrable  Securities on



                                      -39-
<PAGE>

the basis  provided  in any  underwriting  arrangements  approved by the Persons
entitled  hereunder to approve such  arrangements and (b) completes and executes
all questionnaires, powers of attorney, indemnities, underwriting agreements and
other documents required under the terms of such underwriting arrangements.

         9.       Representations and Warranties.

         The Company represents and warrants to, and agrees with, each Purchaser
and each of the Holders from time to time of Registrable Securities that:

                           (a)      Each   registration    statement    covering
                                    Registrable  Securities and each  prospectus
                                    (including   any   preliminary   or  summary
                                    prospectus)  contained  therein or furnished
                                    pursuant to this  Agreement  and any further
                                    amendments  or   supplements   to  any  such
                                    registration  statement or prospectus,  when
                                    it  becomes  effective  or is filed with the
                                    SEC, as the case may be, and, in the case of
                                    an  underwritten   offering  of  Registrable
                                    Securities, at the time of the closing under
                                    the underwriting agreement relating thereto,
                                    will conform in all material respects to the
                                    requirements  of the  Securities Act and the
                                    TIA and the rules and regulations of the SEC
                                    and any such registration  statement and any
                                    amendment   thereto  will  not  include  any
                                    untrue  statement of a material fact or omit
                                    to state any  material  fact  required to be
                                    stated  therein  or  necessary  to make  the
                                    statements  therein not  misleading  and any
                                    such   prospectus   or  any   amendment   or
                                    supplement thereto will not include



                                      -40-
<PAGE>

                                    any untrue  statement of a material  fact or
                                    omit to state a material fact required to be
                                    stated  therein  or  necessary  to make  the
                                    statements  therein not  misleading in light
                                    of the circumstances  then existing;  and at
                                    all times  subsequent to the effective  time
                                    of any such  registration  statement  when a
                                    prospectus would be required to be delivered
                                    under the  Securities  Act,  other than from
                                    (i) such time as a notice  has been given to
                                    Holders of Registrable  Securities  pursuant
                                    to the last  paragraph  of  Section  4(t) or
                                    pursuant to Section  4(k) hereof  until (ii)
                                    such  time  as  the  Company   furnishes  an
                                    amended or supplemented  prospectus pursuant
                                    to Section 4(k) hereof or otherwise gives an
                                    Advice,  each such  registration  statement,
                                    and each  prospectus  (including any summary
                                    prospectus)  con tained therein or furnished
                                    pursuant  to Section  4(k) or  Section  4(g)
                                    hereof,  as then  amended  or  supplemented,
                                    will conform in all material respects to the
                                    requirements  of the  Securities Act and the
                                    TIA and the  rules  and  regulations  of the
                                    Commission  and will not  include any untrue
                                    statement  of any  material  fact or omit to
                                    state a material  fact required to be stated
                                    therein or necessary to make the  statements
                                    therein not  misleading  in the light of the
                                    circumstances   then   existing;   provided,
                                    however,   that  this   representation   and
                                    warranty does not apply to any statements or
                                    omissions from a  registration



                                      -41-
<PAGE>

                                    statement  or  prospectus   (including   any
                                    preliminary  or  summary  prospectus)  based
                                    upon  written  information  furnished to the
                                    Company by any  underwriter,  sales agent or
                                    Holder specifically for use therein.

                           (b)      Any documents  incorporated  by reference in
                                    any  prospectus  referred to in Section 4(a)
                                    hereof, when they become or became effective
                                    or are or were  filed  with the SEC,  as the
                                    case may be, will  conform or  conformed  in
                                    all material respects to the requirements of
                                    the  Securities  Act or the Exchange Act, as
                                    applicable,  and none of such documents will
                                    include or included any untrue  statement of
                                    a  material  fact or will omit or omitted to
                                    state  any  material  fact  required  to  be
                                    stated  therein  or  necessary  to make  the
                                    statements therein not misleading; provided,
                                    however,   that  this   representation   and
                                    warranty does not apply to any statements or
                                    omissions from a  registration  statement or
                                    the prospectus (including any preliminary or
                                    summary   prospectus)   based  upon  written
                                    information  furnished to the Company by any
                                    underwriter,    sales    agent   or   Holder
                                    specifically for use therein.

                           (c)      The  issuance  and  sale of the  Registrable
                                    Securities  did not and  will  not,  and the
                                    execution,  delivery and performance of this
                                    Agreement  and  the   consummation   of



                                      -42-
<PAGE>

                                    the transactions  herein  contemplated  will
                                    not,  result in a breach or violation of any
                                    of  the   terms   and   provisions   of,  or
                                    constitute  a default  under,  any  statute,
                                    rule,  regulation,  order or  policy  of any
                                    governmental  agency  or body or any  court,
                                    domestic  or  foreign,  having  jurisdiction
                                    over the  Company or any  subsidiary  of the
                                    Company  or any  of  their  properties,  the
                                    Credit Agreement (as defined in the Purchase
                                    Agreement)   or  any  other   agreement   or
                                    instrument  to which the Company or any such
                                    subsidiary  is  a  party  or  by  which  the
                                    Company or any such  subsidiary  is bound or
                                    to which the Company or any such  subsidiary
                                    has agreed to become bound,  or to which any
                                    of the properties of the Company or any such
                                    subsidiary  is  subject,  or the  charter or
                                    by-laws (or other  constituent  document) of
                                    the Company or any such subsidiary.

         10.      Miscellaneous

                           (a)      No Inconsistent Agreements.  The Company has
                                    not, as of the date hereof,  and the Company
                                    shall not, after the date of this Agreement,
                                    enter into any agreement with respect to any
                                    of its securities that is inconsistent  with
                                    the  rights   granted  to  the   Holders  of
                                    Registrable  Securities in this Agreement or
                                    otherwise   conflicts  with  the  provisions
                                    hereof. The Company has not



                                      -43-
<PAGE>

                                    entered   and  will  not   enter   into  any
                                    agreement   with   respect  to  any  of  its
                                    securities  that  will  grant to any  Person
                                    piggyback  registration  rights with respect
                                    to a Registration  Statement,  except to the
                                    extent  any  existing  right has  heretofore
                                    been waived.

                           (b)      Adjustments       Affecting      Registrable
                                    Securities.  The Company shall not, directly
                                    or indirectly,  take any action with respect
                                    to the  Registrable  Securities  as a  class
                                    that would  adversely  affect the ability of
                                    the  Holders of  Registrable  Securities  to
                                    include  such  Registrable  Securities  in a
                                    registration  undertaken  pursuant  to  this
                                    Agreement.

                           (c)      Amendments  and Waivers.  The  provisions of
                                    this Agreement may not be amended,  modified
                                    or supplemented,  and waivers or consents to
                                    departures  from the  provisions  hereof may
                                    not be given,  otherwise than with the prior
                                    written  consent  of  the  Company  and  the
                                    Holders  of  not  less  than a  majority  in
                                    Amount of the then  outstanding  Registrable
                                    Securities;  provided, however, that Section
                                    6 and this Section 10(c) may not be amended,
                                    modified or  supplemented



                                      -44-
<PAGE>

                                    without  the prior  written  consent  of the
                                    Company and each Holder  (including,  in the
                                    case  of  an  amendment,   modification   or
                                    supplement  of Section 6, any person who was
                                    a Holder of Registrable Securities, disposed
                                    of pursuant to any Registration  Statement).
                                    Notwithstanding  the foregoing,  a waiver or
                                    consent to depart from the provisions hereof
                                    with   respect  to  a  matter  that  relates
                                    exclusively  to the  rights  of  Holders  of
                                    Registrable  Securities whose securities are
                                    being  sold   pursuant  to  a   Registration
                                    Statement  and  that  does not  directly  or
                                    indirectly   affect,    impair,   limit   or
                                    compromise  the  rights of other  Holders of
                                    Registrable   Securities  may  be  given  by
                                    Holders of at least a majority  in Amount of
                                    the  Registrable  Securities  being  sold by
                                    such Holders  pursuant to such  Registration
                                    Statement;   provided,   however,  that  the
                                    provisions  of  this  sentence  may  not  be
                                    amended,  modified or supplemented except in
                                    accordance   with  the   provisions  of  the
                                    immediately preceding sentence.

                           (d)      Notices.     All     notices    and    other
                                    communications  provided  for  or  permitted
                                    hereunder   shall  be  made  in  writing  by
                                    hand-delivery,



                                      -45-
<PAGE>

                                    registered  first-class  mail,  next-day air
                                    courier or facsimile:

                  (1) if to a Holder of the Registrable Securities,  at the most
         current address of such Holder on the Security  Register (as defined in
         the Indenture),  in the case of Convertible Notes, and the stock ledger
         of the  Company,  in the case of Class A Common  Stock,  with a copy in
         like manner to the Initial Purchasers as follows:

               CREDIT SUISSE FIRST BOSTON CORPORATION
               DEUTSCHE BANK SECURITIES INC.
               LEHMAN BROTHERS INC.
               BANC OF AMERICA SECURITIES LLC
               BEAR, STEARNS & CO. INC.
               SALOMON SMITH BARNEY INC.
               FIRST UNION SECURITIES, INC.
               GOLDMAN, SACHS & CO.
               LEGG MASON WOOD WALKER, INCORPORATED
               MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED
               MORGAN STANLEY & CO. INCORPORATED
               RAYMOND JAMES & ASSOCIATES, INC.
               c/o Credit Suisse First Boston Corporation
               Eleven Madison Avenue
               New York, New York  10010
               Facsimile No:  (212) 325-8278
               Attention:  Investment Banking Department
                           Transactions Advisory Group


         with a copy to:

               Sullivan & Cromwell
               125 Broad Street
               New York, New York  10004
               Facsimile No.:  (212) 558-3588
               Attention:  John T. Bostelman, Esq.

         (2) if to the Initial Purchasers, at the addresses specified in Section
10(d)(1);



                                      -46-
<PAGE>

         (3) if to the Company, at the addresses as follows:

               American Tower Corporation
               116 Huntington Avenue
               Boston, Massachusetts  02116
               Facsimile No.:  (617) 375-7575
               Attention:  Chief Financial Officer

with copies to:

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

         All such notices and  communications  shall be deemed to have been duly
given: when delivered by hand, if personally delivered; five business days after
being deposited in the mail, postage prepaid,  if mailed; one business day after
being  timely  delivered  to  a  next-day  air  courier;  and  when  receipt  is
acknowledged by the addressee, if sent by facsimile.

                           (e)      Successors and Assigns. This Agreement shall
                                    inure to the benefit of and be binding  upon
                                    the  successors  and  assigns of each of the
                                    parties   hereto,   including  the  Holders;
                                    provided, however, that this Agreement shall
                                    not inure to the  benefit  of or be  binding
                                    upon  a  successor  or  assign  of a  Holder
                                    unless  and   except  to  the  extent   such
                                    successor   or  assign   holds   Registrable
                                    Securities.

                           (f)      Counterparts. This Agreement may be executed
                                    in any  number  of  counterparts  and by the
                                    parties  hereto  in  separate  counterparts,
                                    each of  which  when so  executed  shall  be
                                    deemed  to be an  original



                                      -47-
<PAGE>

                                    and  all  of  which  taken   together  shall
                                    constitute one and the same agreement.

                           (g)      Headings. The headings in this Agreement are
                                    for  convenience of reference only and shall
                                    not limit or  otherwise  affect the  meaning
                                    hereof.

                           (h)      Governing  Law.  THIS  AGREEMENT   SHALL  BE
                                    GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH
                                    THE  LAWS  OF  THE  STATE  OF NEW  YORK,  AS
                                    APPLIED  TO  CONTRACTS  MADE  AND  PERFORMED
                                    WHOLLY WITHIN THE STATE OF NEW YORK, WITHOUT
                                    REGARD TO  PRINCIPLES  OF  CONFLICTS OF LAW.
                                    EACH OF THE PARTIES  HERETO AGREES TO SUBMIT
                                    TO THE  JURISDICTION  OF THE  COURTS  OF THE
                                    STATE   OF  NEW  YORK  IN  ANY   ACTION   OR
                                    PROCEEDING  ARISING  OUT OF OR  RELATING  TO
                                    THIS AGREEMENT.

                           (i)      Severability.   If  any   term,   provision,
                                    covenant or restriction of this Agreement is
                                    held by a court of competent jurisdiction to
                                    be invalid,  illegal, void or unenforceable,
                                    the  remainder  of  the  terms,  provisions,
                                    covenants and  restrictions set forth herein
                                    shall  remain in full  force and  effect and
                                    shall  in no way be  affected,  impaired  or
                                    invalidated,  and the parties  hereto  shall
                                    use their best efforts to find and employ an
                                    alternative  means  to  achieve  the same or
                                    substantially   the  same   result  as  that
                                    contemplated   by  such   term,   provision,
                                    covenant  or   restriction.   It  is  hereby
                                    stipu-



                                      -48-
<PAGE>

                                    lated and  declared to be the  intention  of
                                    the  parties  that they would have  executed
                                    the remaining terms,  provisions,  covenants
                                    and  restrictions  without  including any of
                                    such that may be hereafter declared invalid,
                                    illegal, void or unenforceable.

                           (j)      Securities   Held  by  the  Company  or  Its
                                    Affiliates. Whenever the consent or approval
                                    of  Holders  of a  specified  percentage  in
                                    Amount of Registrable Securities is required
                                    hereunder,  Registrable  Securities  held by
                                    the Company or its  affiliates (as such term
                                    is defined in Rule 405 under the  Securities
                                    Act)  shall not be  counted  in  determining
                                    whether  such  consent or approval was given
                                    by the Holders of such required percentage.

                           (k)      Third   Party   Beneficiaries.   Holders  of
                                    Registrable  Securities  are intended  third
                                    party  beneficiaries  of this  Agreement and
                                    this  Agreement  may  be  enforced  by  such
                                    Persons.

                           (l)      Entire Agreement.  This Agreement,  together
                                    with   the   Purchase   Agreement   and  the
                                    Indenture,  is  intended by the parties as a
                                    final  and   exclusive   statement   of  the
                                    agreement and  understanding  of the parties
                                    hereto  in  respect  of the  subject  matter
                                    contained herein and therein and any and all
                                    prior    oral   or    written    agreements,
                                    representations,  or warranties,  contracts,



                                      -49-
<PAGE>

                                    understandings,              correspondence,
                                    conversations   and  memoranda  between  the
                                    Initial  Purchasers  on the one hand and the
                                    Company  on the  other,  or between or among
                                    any   agents,   representatives,    parents,
                                    subsidiaries,  affiliates,  predecessors  in
                                    interest  or  successors  in  interest  with
                                    respect  to the  subject  matter  hereof and
                                    thereof  are  merged   herein  and  replaced
                                    hereby.


                                      -50-
<PAGE>

                  IN WITNESS  WHEREOF,  the parties have executed this Agreement
as of the date first written above.


                                       AMERICAN TOWER CORPORATION



                                       By: /s/ Justin D. Benincasa
                                                Name:  Justin D. Benincasa
                                                Title: Vice President/
                                                       Corporate Controller


                                       CREDIT SUISSE FIRST BOSTON
                                                CORPORATION
                                       DEUTSCHE BANK SECURITIES INC.
                                       LEHMAN BROTHERS INC.
                                       BANC OF AMERICA SECURITIES LLC
                                       BEAR, STEARNS & CO. INC.
                                       SALOMON SMITH BARNEY INC.
                                       FIRST UNION SECURITIES, INC.
                                       GOLDMAN, SACHS & CO.
                                       LEGG MASON WOOD WALKER,
                                                INCORPORATED
                                       MERRILL LYNCH, PIERCE, FENNER &
                                                SMITH INCORPORATED
                                       MORGAN STANLEY & CO. INCORPORATED
                                       RAYMOND JAMES & ASSOCIATES, INC.


                                       By:  CREDIT SUISSE FIRST BOSTON
                                                       CORPORATION


                                       By: /s/ Kristin M. Allen
                                                Name:  Kristin M. Allen
                                                Title: Managing Director