EXHIBIT 10


                             SUBSCRIPTION AGREEMENT


         This  Subscription  Agreement (this  "Agreement") is entered into as of
February 7, 2000 by and between  Reckson  Service  Industries,  Inc., a Delaware
corporation ("RSI"), and VANTAS Incorporated, a Nevada corporation ("VANTAS").


         WHEREAS,  RSI and VANTAS have entered into that certain  Agreement  and
Plan of Merger,  dated  January 20,  2000,  with HQ Global  Workplaces,  Inc., a
Delaware  corporation  ("HQ"),  and CarrAmerica Realty  Corporation,  a Maryland
corporation,  (the "Merger Agreement")  pursuant to which VANTAS is to be merged
(the "Merger") with and into HQ, with HQ being the surviving corporation;


         WHEREAS,  in accordance with the terms of the Merger Agreement,  VANTAS
obtained an  irrevocable  letter of credit from Bankers Trust Company  ("Bankers
Trust") in favor of HQ and  guaranteed  by RSI in the amount of $35 million (the
"Letter of Credit");


         WHEREAS, pursuant to the Equity Interest Pledge and Security Agreement,
dated  February 7, 2000,  by and between  RSI and Bankers  Trust (the  "Security
Agreement"),  RSI has pledged  11,299,072 shares of the capital stock in VANTAS,
as more fully set forth on  Schedule A to this  Agreement,  as  collateral  (the
"Collateral") securing the Letter of Credit;


         WHEREAS, if there is a foreclosure on the Collateral, VANTAS has agreed
to issue to RSI, at RSI's  election,  shares of the capital stock of VANTAS (the
"Securities") to reimburse RSI for the loss of the Collateral; and


         WHEREAS, the parties hereto acknowledge that,  notwithstanding anything
contained in this agreement,  if there is a foreclosure on the  Collateral,  RSI
shall maintain its subrogation  rights with respect to the Letter of Credit.  To
the extent that RSI does not exercise its rights pursuant to this agreement, RSI
may pursue such subrogation rights.


         NOW, THEREFORE, in consideration of the mutual covenants and conditions
set forth  herein and other good and  valuable  consideration  the  receipt  and
sufficiency  of  which is  hereby  acknowledged,  the  parties  hereto  agree as
follows:

         1. Amount and  Consideration.  In consideration of RSI securing VANTAS'
obligations under the Letter of Credit,  VANTAS agrees that, if, and only to the
extent,  Bankers Trust  forecloses on the  Collateral  (other than a foreclosure
resulting from RSI's gross  negligence),  it shall be obligated to issue to RSI,
at RSI's election, the Securities. Such Securities shall have the same terms and
conditions as the securities comprising the Collateral which was foreclosed upon
and not otherwise  returned to RSI by Bankers Trust pursuant to the terms of the
Security Agreement with the value of such Securities equal to the value ascribed
to VANTAS common and preferred stock in such foreclosure sale;

         2. Restrictions on Transferability of Securities. RSI realizes that the
Securities  are not, and will not be,  registered  under the  Securities  Act of
1933, as amended (the "Securities

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Act"), or the securities laws of any state.  RSI agrees that the Securities will
not be sold, offered for sale, transferred,  pledged, hypothecated, or otherwise
disposed of except in compliance  with the Securities  Act and applicable  state
securities laws. RSI understands that any sale, transfer, pledge, hypothecation,
or other  disposition  of the  Securities  may require in some  states  specific
approval by the  appropriate  governmental  agency or commission in such states.
RSI has been advised that the Company has no obligation, and does not intend, to
cause the Securities to be registered under the Securities Act or to comply with
the requirements  for any exemption under the Securities Act,  including but not
limited  to those  provided  by Rule 144 and Rule  144A  promulgated  under  the
Securities  Act,  which  would  permit  the  Securities  to be sold by RSI.  RSI
understands  that it is not anticipated that there will be any market for resale
of the  Securities  and that the  transfer  of the  Securities  is  specifically
restricted under this Subscription  Agreement and the Securities Act, and may be
restricted  by applicable  state  securities  laws.  RSI  understands  the legal
consequences  of the  foregoing to mean that RSI must bear the economic  risk of
its investment in VANTAS for an indefinite  period of time. RSI understands that
instruments,  if any,  representing the Securities may bear legends  restricting
the transfer thereof.

         3. Acceptance of Subscription.  VANTAS understands and agrees that RSI,
in its sole  discretion,  reserves  the right to  accept or reject  this and any
other  subscription  for the Securities in whole or in part at any time prior to
the acceptance of such  Securities,  notwithstanding  prior receipt by VANTAS of
notice of acceptance.  In the event that this  subscription is rejected in whole
or in part or, if the offering of the Securities to RSI is not  consummated  for
any  reason,  this  subscription  shall  be  deemed  to  be  rejected  and  this
Subscription Agreement shall thereafter have no force or effect to that extent.

         4.  Representations  and Warranties of VANTAS.  In connection  with the
transactions contemplated herein, VANTAS warrants and represents to RSI that (a)
VANTAS is a duly organized  corporation,  validly  existing and in good standing
under the laws of the State of Nevada,  (b) the  execution  and delivery of this
Subscription  Agreement and the performance of all acts  contemplated  hereunder
been duly authorized by all necessary  actions and, to VANTAS'  knowledge,  will
not  constitute a breach or violation of, or a default  under,  any agreement by
which VANTAS or any of its  properties is bound,  nor  constitute a violation of
any law, administrative regulation or court decree applicable VANTAS and (c) the
Securities have been duly authorized and shall be validly issued.

         5. Notices. Any consent, request, waiver, notice or other communication
or document  required or permitted to be given pursuant to any provision of this
Subscription  Agreement  ("Notice")  shall be  deemed  duly  given  only when in
writing,  signed by or on behalf of RSI giving such Notice,  and (i)  personally
delivered  (with  receipt  acknowledged  by the  recipient  or its agent),  (ii)
deposited in a designated  U.S. mail  depositary,  registered or certified mail,
return receipt  requested,  postage prepaid,  or (iii) sent by overnight courier
(with receipt  acknowledged by the recipient or its agent),  addressed to VANTAS
to its principal  office at 90 Park Avenue,  New York, NY 10016. Any such Notice
shall be deemed  received (x) upon  personal  delivery,  (y) five (5) days after
mailing  as  provided  above,  or (z) one (1) day  after  sending  by  overnight
courier.

         6.  Counterparts.  This Subscription  Agreement may be executed through
the use of separate  signature pages or in any number of counterparts,  and each
such counterpart  shall, for

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all purposes,  constitute one agreement binding on all parties,  notwithstanding
that all parties are not signatories to the same counterpart.

         7. Entire Agreement.  This Subscription  Agreement  contains the entire
agreement of the parties with respect to the subject matter hereof and there are
no  representations,  covenants or other agreements except as stated or referred
to herein.

         8.  Severability.  Each  provision  of this  Subscription  Agreement is
intended to be  severable  from every other  provision,  and the  invalidity  or
illegality  of any portion  hereof  shall not affect the validity or legality of
the remainder hereof.

         9.  Assignability.  This Subscription  Agreement is not transferable or
assignable by either party hereto.

         10.  Headings and  Captions.  The headings and captions for the various
sections of this  Subscription  Agreement are for  convenience of reference only
and shall in no way modify or affect the meaning or  construction  of any of the
terms or provisions hereof.

         11.  Applicable Law. This  Subscription  Agreement shall be governed by
and construed in accordance with the law of the State of New York without giving
effect to the conflicts of laws principles thereof.

         12.  Choice of  Jurisdiction.  The  parties  agree  that any  action or
proceeding arising,  directly,  indirectly or otherwise, in connection with, out
of or from this  Subscription  Agreement,  any breach hereof or any  transaction
covered hereby shall be resolved within the State of New York. Accordingly,  the
parties consent and submit to the  jurisdiction of the United States federal and
state courts located within the State of New York.

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



                                              VANTAS INCORPORATED



                                              By:
                                                 -------------------------------
                                              Name:
                                                   -----------------------------
                                              Title:
                                                    ----------------------------



                                              RECKSON SERVICE INDUSTRIES, INC.



                                              By:
                                                 -------------------------------
                                              Name:
                                                   -----------------------------
                                              Title:
                                                    ----------------------------




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