EXHIBIT 10.12
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                             STOCK OPTION AGREEMENT

         THIS STOCK OPTION  AGREEMENT  (this  "Agreement"),  is made and entered
into  as of the  5th  day of  March,  1997  by and  between  SBA  COMMUNICATIONS
CORPORATION,  a Florida  corporation (the  "Company"),  and ROBERT M. GROBSTEIN,
(the "Optionee");

                              W I T N E S S E T H:

         WHEREAS,  the  Optionee  has agreed to  terminate  all of his  existing
employment and incentive  agreements and stock options with SBA, Inc., a Florida
corporation,  and SBA Leasing,  Inc., a Florida  corporation,  both wholly-owned
subsidiaries of the Company,  and to accept employment with the Company pursuant
to the terms and conditions of that certain  Employment  Agreement,  dated as of
January  1,  1997,   between  the  Company  and  the  Optionee  (the   "Employee
Agreement"); and

         WHEREAS,  in exchange for Optionee  terminating his rights with respect
to options  entitling  him to purchase  shares of capital stock in SBA, Inc. and
SBA Leasing,  Inc., the Company desires to grant to the Optionee, in addition to
88,236  shares of the Company's  Class A Common Stock,  $.01 par value per share
(the "Class A Common  Stock"),  certain options to purchase  additional  Class A
Common Stock, all as more particularly set forth herein;

         NOW, THEREFORE,  in consideration of the mutual premises and covenants,
and other good and valuable consideration,  the receipt and adequacy of which is
hereby acknowledged, it is hereby agreed as follows:

         1. Grant of Option.  Subject to and upon the terms and  conditions  set
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forth in this Agreement,  the Company hereby grants to the Optionee options (the
"Options")  to purchase up to three  hundred  eighty six thousand  seven hundred
sixty four (386,764) shares of Class A Common Stock at an exercise price of $.05
per share.

         2. Time of Exercise.  The options are immediately  exercisable and will
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expire and be of no further force or effect if unexercised by December 31, 2006.

         3. No Transferability.  The options may not be sold, conveyed, pledged,
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hypothecated or otherwise  transferred in any manner by the Optionee without the
prior written consent of the Company; provided, however, that the options may be
transferred  pursuant to will or the laws of intestacy following Optionee's life
or,  during  Optionee's  life,  to a person  or  entity  who  would be deemed an
Eligible Class B Stockholder  as such term is defined in the Company's  Articles
of Incorporation and substituting in such definition as appropriate Optionee for
Steven M. Bernstein.  No such sale,  transfer or hypothecation  may occur in any
event except in compliance with federal and state securities laws, as determined
to the satisfaction of the Company and its counsel in their sole discretion.

         4. Partial  Exercise.  Exercise of the options up to the extent  stated
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may be made in part at any time and  from  time to time  within  the  limits  of
Section 2 hereof, except that the options may

                                                        

 
not be exercised for a fraction of a share. Any fractional share with respect to
which  an  installment  of  the  options  cannot  be  exercised  because  of the
limitation  contained in the  preceding  sentence  shall  remain  subject to the
options and shall be available for later  purchase by the Optionee in accordance
with the terms hereof.

         5.  Payment  of Price.  The option  price of each  option is payable in
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lawful currency of the United States and must be paid in cash or by certified or
cashier's  check,  or any  combination of the foregoing,  equal in amount to the
option price.

         6. Restricted Shares; Purchase for Investment. The Optionee agrees that
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(i) his purchase of shares of Common Stock of the Company (the "Shares") upon an
exercise  of an  option  hereunder  will  not be  made  with a view  toward  the
"distribution"  of such Shares,  as defined in the  Securities  Act of 1933,  as
amended  (the  "1933  Act");   (ii)  such  Shares  may  not  be  transferred  or
hypothecated unless, in the opinion of counsel to the Company,  such transfer or
hypothecation  would be in compliance  with the  registration  provisions of the
1933 Act or pursuant to an exemption  therefrom;  and (iii) that the certificate
for the Shares so purchased may be inscribed with a legend to ensure  compliance
with the 1933 Act.  Optionee  understands that the Shares will not be registered
under  the 1933  Act,  or under the laws of any  jurisdiction.  Optionee  hereby
represents and warrants that Optionee, or through his advisers, is sophisticated
and experienced in financial  business and investment  matters and, as a result,
Optionee is in a position to evaluate the merits and risks of an  investment  in
the Company.

         7. Method of Exercising Option.  Subject to the terms and conditions of
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this  Agreement,  the options may be exercised  by providing  the Company at the
Consummation Time with payment of the full option price of such Shares,  and the
Company shall deliver a certificate or certificates  representing such Shares as
soon as  practicable  after such payment shall be received.  The  certificate or
certificates  for the Shares as to which an option  shall have been so exercised
shall be registered in the name of the Optionee or permitted  assignee and shall
be delivered to the  Optionee or  permitted  assignee.  All Shares that shall be
purchased upon the exercise of an option as provided  herein shall be fully paid
and non-assessable. The Optionee shall not have the rights of a shareholder with
respect  to the  Shares  covered  by the  options  hereunder  until  the date of
issuance of a stock  certificate to him for such Shares.  No adjustment shall be
made for  dividends  or similar  rights for which the record  date is before the
date such stock certificate is issued.

         8. No Obligation to Exercise  Option.  The grant and  acceptance of the
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options hereunder imposes no obligation on the Optionee to exercise the options.

         9.  Amendments.  The  provisions of this  Agreement may not be amended,
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supplemented,  waived or  changed  orally,  but only by a writing  signed by the
party  as to whom  enforcement  of any such  amendment,  supplement,  waiver  or
modification is sought and making specific reference to this Agreement.


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         10.  Assignments.  Except as otherwise  provided herein, no party shall
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assign his or its rights and/or obligations  hereunder without the prior written
consent of each other party to this Agreement.

         11. Further  Assurances.  The parties hereby agree from time to time to
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execute and deliver such further and other transfers,  assignments and documents
and do all matters  and things  which may be  convenient  or  necessary  to more
effectively and completely carry out the intentions of this Agreement.

         12. Binding Effect.  All of the terms and provisions of this Agreement,
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whether so expressed or not, shall be binding upon, inure to the benefit of, and
be  enforceable  by the  parties  and their  respective  legal  representatives,
successors and permitted assigns.

         13. Notices. All notices,  requests,  consents and other communications
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required or permitted under this Agreement shall be in writing  (including telex
and  telegraphic  communication)  and shall be (as elected by the person  giving
such notice) hand delivered by messenger or courier  service,  telecommunicated,
or mailed  (airmail if  international)  by registered or certified mail (postage
prepaid), return receipt requested, addressed to:

If to Optionee:

         Robert M. Grobstein
         18949 Treble Lane
         Boca Raton, Florida  33498
         Telephone: (561) 852-8279

If to the Company:

         SBA Communications Corporation
         Attention: Steven E. Bernstein, President
         6001 Broken Sound Parkway, Suite 404
         Boca Raton, Florida 33487
         Telephone: (561) 995-7670
         Telefax: (561) 995-7626

or to such other address as any party may designate by notice complying with the
terms of this  Section.  Each such notice shall be deemed  delivered  (a) on the
date delivered if by personal  delivery;  (b) on the date of  transmission  with
confirmed  answer back if by electronic  transmission;  and (c) on the date upon
which the  return  receipt  is signed or  delivery  is  refused or the notice is
designated by the postal authorities as not deliverable,  as the case may be, if
mailed.


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         14. Headings. The headings contained in this Agreement are for         
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convenience of reference only, and shall not limit or otherwise affect in any
way the meaning or interpretation of this Agreement.

         15. Severability.  If any part of this Agreement or any other Agreement
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entered into pursuant  hereto is contrary to,  prohibited  by or deemed  invalid
under  applicable law or regulation,  such provision shall be  inapplicable  and
deemed  omitted  to the  extent so  contrary,  prohibited  or  invalid,  but the
remainder hereof shall not be invalidated  thereby and shall be given full force
and  effect  so far as  possible.  If any  provision  of this  Agreement  may be
construed in two or more ways,  one of which would render the provision  invalid
or  otherwise  voidable or  unenforceable  and another of which would render the
provision  valid and  enforceable,  such provision  shall have the meaning which
renders it valid and enforceable.

         16. Survival. All covenants, agreements, representations and warranties
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made herein or  otherwise  made in writing by any party  pursuant  hereto  shall
survive the execution and delivery of this Agreement and the consummation of the
transactions contemplated hereby.

         17.  Waivers.  The failure or delay of any party at any time to require
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performance by another party of any provision of this Agreement,  even if known,
shall  not  affect  the  right of such  party  to  require  performance  of that
provision or to exercise any right, power or remedy hereunder, and any waiver by
any  party of any  breach  of any  provision  of this  Agreement  should  not be
construed as a waiver of any continuing or succeeding  breach of such provision,
a waiver of the  provision  itself,  or a waiver of any  right,  power or remedy
under this Agreement.  No notice to or demand on any party in any case shall, of
itself,  entitle such party to any other or further  notice or demand in similar
or other circumstances.

         18.  Jurisdiction and Venue. The parties acknowledge that a substantial
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portion of negotiations, anticipated performance and execution of this Agreement
occurred  or shall occur in Palm Beach  County,  Florida,  and that,  therefore,
without limiting the jurisdiction or venue of any other federal or state courts,
each of the parties  irrevocably and  unconditionally  (i) agrees that any suit,
action or legal  proceeding  arising out of or relating to this Agreement may be
brought in the courts of record of the State of Florida in Palm Beach  County or
the court of the United States,  Southern District of Florida;  (ii) consents to
the  jurisdiction  of each such court in any suit,  action or proceeding;  (iii)
waives any objection  which it may have to the laying of venue of any such suit,
action or proceeding in any of such courts;  and (iv) agrees that service of any
court  paper  may be  effected  on such  party  by  mail,  as  provided  in this
Agreement,  or in such other manner as may be provided under  applicable laws or
court rules in said state.

         19. Enforcement Costs. If any civil action,  arbitration or other legal
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proceeding is brought for the  enforcement of this  Agreement,  or because of an
alleged dispute,  breach,  default or  misrepresentation  in connection with any
provision of this Agreement, the successful or prevailing party or parties shall
be entitled to recover  reasonable  attorneys' fees, sales and use taxes,  court
costs and all expenses  even if not taxable as court costs  (including,  without
limitation, all such fees, taxes,

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costs  and  expenses   incident  to  arbitration,   appellate,   bankruptcy  and
post-judgment proceedings),  incurred in that civil action, arbitration or legal
proceeding,  in addition to any other  relief to which such party or parties may
be entitled. Attorneys' fees shall include, without limitation,  paralegal fees,
investigative  fees,  administrative  costs,  sales  and use taxes and all other
charges billed by the attorney to the prevailing party.

         20. Remedies  Cumulative.  No remedy herein conferred upon any party is
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intended to be  exclusive  of any other  remedy,  and each and every such remedy
shall be  cumulative  and  shall be in  addition  to every  other  remedy  given
hereunder  or now or  hereafter  existing  at law or in equity or by  statute or
otherwise.  No single or partial  exercise  by any party of any right,  power or
remedy hereunder shall preclude any other or further exercise thereof.

         21. Governing Law. This Agreement and all transactions contemplated by
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this Agreement shall be governed by, and construed and enforced in accordance
with, the laws of the State of Florida.

         22.   Entire   Agreement.   This   Agreement   represents   the  entire
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understanding  and  agreement  between the parties  with  respect to the subject
matter  hereof,  and  supersedes  all  other  negotiations,  understandings  and
representations (if any) made by and between such parties.

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


                                           SBA COMMUNICATIONS CORPORATION


                                                /s/  Steven E. Bernstein
                                           By:__________________________________
                                              Steven E. Bernstein, President


                                                /s/  Robert M. Grobstein
                                              ----------------------------------
                                              Robert M. Grobstein





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