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                                                                   Exhibit 10.15

                          1201 CONNECTICUT AVENUE, N.W.
                                WASHINGTON, D.C.

                                    * * * * *

                           PURCHASE AND SALE AGREEMENT

                                     BETWEEN

                      THE EQUITABLE LIFE ASSURANCE SOCIETY
                              OF THE UNITED STATES,
               a New York corporation (solely on behalf of and for
                   the benefit of its Separate Account 16-III,
                     known as the "Value Enhancement Fund"),

                                    AS SELLER

                                       AND

                       MACK-CALI REALTY ACQUISITION CORP.,
                             a Delaware corporation

                                  AS PURCHASER

                               As of June 30, 1999

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                           PURCHASE AND SALE AGREEMENT

      THIS PURCHASE AND SALE AGREEMENT (the "Agreement") is made as June 30,
1999 (the "Effective Date"), by and between THE EQUITABLE LIFE ASSURANCE SOCIETY
OF THE UNITED STATES, a New York corporation (solely on behalf of and for the
benefit of its Separate Account 16-III, known as the "Value Enhancement Fund")
("Seller"), having its home office at 1290 Avenue of the Americas, New York, New
York 10104, and MACK-CALI REALTY ACQUISITION CORP., a Delaware corporation
("Purchaser"), having an office c/o Mack-Cali Realty Corporation, 11 Commerce
Drive, Cranford, New Jersey 07016.

                              W I T N E S S E T H:

                                              65535RT65535CLE IPURCHASE AND SALE

I.1 Agreement of Purchase and Sale. Subject to the terms and conditions
hereinafter set forth, Seller agrees to sell and convey and Purchaser agrees to
purchase the following:

      (1) that certain tract or parcel of land situated in Washington, D.C.,
      more particularly described on Exhibit A attached hereto and made a part
      hereof, together with all and singular the rights and appurtenances
      pertaining to such property, including any right, title and interest of
      Seller in and to adjacent streets, alleys or rights-of-way, all mineral
      and water rights, all easements, licenses, and covenants, and other
      appurtenances used in connection with the beneficial use and enjoyment of
      the Land and the Improvements (as hereinafter defined) (the property
      described in clause (a) of this Section 1.1 being herein referred to
      collectively as the "Land");

      (2) the buildings, structures, fixtures and other improvements on the
      Land, including specifically, without limitation, that certain office
      building located thereon having a street address of 1201 Connecticut
      Avenue, N.W., Washington, D.C. (the property described in clause (b) of
      this Section 1.1 being herein referred to collectively as the
      "Improvements");

      (3) all of Seller's right, title and interest in and to all tangible
      personal property upon the Land or within the Improvements, including
      specifically, without limitation, appliances, fixtures, furniture,
      carpeting, draperies and curtains, equipment, tools and supplies, and
      other items of personal property (excluding cash) used exclusively in
      connection with the operation of the Land and the Improvements and only as
      specifically described on Exhibit B attached hereto and made a part hereof
      (the property described in clause (c) of this Section 1.1 being herein
      referred to collectively as the "Personal Property");


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      (4) all of Seller's right, title and interest in and to all agreements
      listed and described on Exhibit C (the "Lease Schedule") attached hereto
      and made a part hereof (all of which are in full force and effect as of
      the Effective Date), pursuant to which any portion of the Land or the
      Improvements is used or occupied by anyone other than Seller ("the
      Leases"), together with all guaranties provided thereunder (if any) and
      all rents, additional rents, reimbursements, profits, income, receipts and
      the amount deposited, whether in the form of cash or letter of credit (the
      "Security Deposit"), under any Lease in the nature of security for the
      performance of the obligations of the tenant (individually, a "Tenant",
      and collectively, "Tenants") under the Leases; and

      (5) all of Seller's right, title and interest in and to (i) all assignable
      contracts and agreements (collectively, the "Operating Agreements") listed
      and described on Exhibit D (the "Operating Agreements Schedule") attached
      hereto and made a part hereof, relating to the upkeep, repair, maintenance
      or operation of the Land, the Improvements or the Personal Property which
      will extend beyond the date of Closing (as such term is defined in Section
      4.1 hereof), including specifically, without limitation, all assignable
      equipment leases, and (ii) all assignable existing warranties and
      guaranties (expressed or implied), and all permits, licenses, approvals
      and telephone numbers issued or assigned to Seller in connection with the
      Improvements or the Personal Property (the property described in clause
      (e) of this Section 1.1 being sometimes herein referred to collectively as
      the "Intangibles"); provided, however, that Purchaser shall not be
      obligated to assume any management agreements, leasing commission
      agreements, or any Operating Agreement (A) which Purchaser has advised
      Seller in writing (not later than ten (10) days after the Effective Date)
      to terminate as of Closing and which can, by its terms, be so terminated
      without the payment of any penalties, fees or liquidated amounts, or (B)
      which requires the payment of a penalty, fee or liquidated amount in order
      to terminate the same; and further provided that with respect to any
      leasing commission agreements, the respective rights and obligations of
      Seller and Purchaser shall be as set forth in this Agreement;

      (6) all promotional material, marketing materials, brochures, photographs
      (collectively, "Promotional Materials"), books, records, tenant data,
      leasing material and forms, past and current rent rolls, files,
      statements, real property tax returns, market studies, keys, plans,
      specifications, reports, tests and other materials of any kind owned by or
      in the possession of Seller or Seller's property manager which are or may
      be used by Seller in the use and operation of the Land, the Improvements
      or the Personal Property (collectively, and together with the Promotional
      Materials, the "Books and Records") (it being understood, however, that
      such materials shall not include any materials not directly related to
      leasing, maintenance and/or management of the Property such as, without
      limitation, Seller's internal memoranda, financial projections, budgets,
      appraisals, accounting and tax records and similar proprietary, elective
      or confidential information); and


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      (7) all other rights, privileges and appurtenances owned by Seller, if
      any, and in any way related to the rights and interests described above in
      this Section 1.1

I.2 Property Defined. The Land, the Improvements, the Personal Property, the
Leases, the Intangibles and the Books and Records and the other property
interests being conveyed hereunder and the Intangibles are hereinafter sometimes
referred to collectively as the "Property."

I.3 Permitted Exceptions. The Property shall be conveyed as required by this
Agreement, but shall be subject to the matters which are, or are deemed to be,
Permitted Exceptions pursuant to Article II hereof (herein referred to
collectively as the "Permitted Exceptions").

I.4 Purchase Price. Seller is to sell and Purchaser is to purchase the Property
for a total of THIRTY-TWO MILLION FIVE HUNDRED FIFTY THOUSAND AND 00/100 DOLLARS
($32,550,000.00) (the "Purchase Price").

I.5 Payment of Purchase Price. The Purchase Price, as increased or decreased by
prorations and adjustments as herein provided, shall be payable in full at
Closing in cash by wire transfer of immediately available federal funds to a
bank account designated by Seller in writing, together with wire transfer
instructions, to Purchaser not less than two (2) business days prior to the
Closing.

I.6 Earnest Money.

      (a)   Simultaneously with the execution and delivery of this Agreement,
            Purchaser is depositing with Commercial Settlements, Inc. (the
            "Escrow Agent"), having its office at 1413 K Street, N.W., 12th
            Floor, Washington, D.C. 20005 Attention: Stuart S. Levin, the sum of
            One Million and No/100 Dollars ($1,000,000.00) (the "Earnest Money")
            in good funds, either by certified bank or cashier's check or by
            federal wire transfer. Purchaser shall provide Purchaser's federal
            tax identification number to Escrow Agent concurrently with the
            making of such deposit. The Escrow Agent shall hold the Earnest
            Money in an interest-bearing account in accordance with the terms
            and conditions of this Agreement. All interest accruing on such sum
            shall become a part of the Earnest Money and shall be distributed as
            Earnest Money in accordance with the terms of this Agreement.

      (b)   In the event of termination of this Agreement prior to Closing, the
            Escrow Agent shall disburse the Earnest Money in accordance with the
            provisions of this Agreement governing such termination. Upon
            receipt of a party's written demand for the Earnest Money, the
            Escrow Agent shall promptly mail a copy of such demand to the other
            party, who shall then have five (5) days to dispute the disbursement
            by sending written notice of such objection to the Escrow Agent. In
            the event of any dispute between Seller and Purchaser regarding the
            disbursement


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            of the Earnest Money, or in the event the Escrow Agent shall receive
            conflicting demands or instructions with respect thereto, the Escrow
            Agent shall withhold disbursement of the Earnest Money until such
            dispute is resolved. Alternatively, the Escrow Agent shall be
            entitled to deposit the Earnest Money into a court of general
            jurisdiction in the District of Columbia or the United States
            District Court for the District of Columbia, and to interplead
            Seller and Purchaser in connection therewith. The costs of any such
            action for interpleader shall be paid by whichever of Seller or
            Purchaser is the losing party. The Escrow Agent shall not be liable
            for any damage, liability or loss arising out of its services
            pursuant to this Agreement, except for damage, liability or loss
            resulting from the willful or negligent conduct of the Escrow Agent
            or any of its officers or employees.

I.7 Independent Contract Consideration. In addition to the Earnest Money,
Purchaser shall, concurrently with its execution hereof, deliver to Seller a
check in the amount of ONE HUNDRED AND NO/100ths DOLLARS ($100.00), which amount
Seller and Purchaser agree has been bargained for as consideration for Seller's
execution and delivery of this Agreement and Purchaser's right to inspect the
Property pursuant to Article III. Such sum is in addition to and independent of
any other consideration or payment provided for in this Agreement and is
nonrefundable in all events.

                                              65535RT65535CLE IITITLE AND SURVEY

II.1 Title Examination; Commitment for Title Insurance. Seller has obtained and
delivered to Purchaser at no cost to Purchaser and the surveyor preparing the
Survey, from Commonwealth Land Title Insurance Company (the "Title Company"), a
current ALTA title insurance commitment No. 99-1135 (the "Title Commitment")
covering the Property and a copy of each document referenced in the Title
Commitment as an exception to title to the Property. Purchaser shall have until
June 21, 1999 (the "Title Exam Deadline"), to review the Title Commitment
(regardless if such date occurs prior to the Effective Date). At Closing, at
Purchaser's expense, Purchaser shall obtain from the Title Company an Owner's
Policy of Title Insurance in the full amount of the Purchase Price pursuant to
Section 2.4 hereof.

II.2 Survey. Seller has obtained and delivered to Purchaser and the Title
Company at no cost to Purchaser a current ALTA survey of the Property prepared
by Bernard F. Locraft Civil Engineers (the "Survey") reflecting the total area
of the Property, the location of all improvements, recorded easements and
encroachments, if any, located thereon and other matters of record with respect
thereto. Purchaser shall pay any costs associated with any changes to the Survey
(or certifications thereon or updates thereto) requested by Purchaser.

II.3 Title Objections; Cure of Title Objections.

      (a)   Purchaser shall have until the Title Exam Deadline to notify Seller,
            in writing, of such objections as Purchaser may have to anything
            contained in the Title


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            Commitment or the Survey. (Seller shall use good faith efforts, but
            without any cost or liability to Seller, to remove or cure title
            objections raised by Purchaser as to matters set forth on the Title
            Commitment.) Any item contained in the Title Commitment or any
            matter shown on the Survey to which Purchaser does not object prior
            to the Title Exam Deadline shall be deemed a Permitted Exception. In
            the event Purchaser shall notify Seller of objections to title or to
            matters shown on the Survey prior to the Title Exam Deadline, Seller
            shall have the right, but not the obligation, to cure such
            objections; provided, however, that notwithstanding anything to the
            contrary contained in this Agreement, Seller shall be obligated, at
            its sole cost and expense, to take such actions as may be necessary
            to cause the Title Company to delete as an exception, by payment or
            other appropriate measure of satisfaction, any mechanic's lien, IRS
            payment lien, judgment lien or deed of trust or other financing lien
            created prior to Closing by any action or inaction of Seller, which
            liens shall be deemed to be excluded from the term "Permitted
            Exceptions."

      (b)   Within ten (10) days after receipt of Purchaser's notice of
            objections, Seller shall notify Purchaser in writing whether Seller
            elects to attempt to cure such objections. If Seller fails to give
            Purchaser such notice of election, then Seller shall be deemed to
            have elected not to attempt to cure the matter. If Seller elects to
            attempt to cure, and provided that Purchaser shall not have
            terminated this Agreement in accordance with Section 3.2 hereof,
            Seller shall have until the date of Closing to attempt to remove,
            satisfy or cure the same and for this purpose Seller shall be
            entitled to a reasonable adjournment of the Closing if additional
            time is required, but in no event shall the adjournment exceed
            thirty (30) days after the date for Closing set forth in Section 4.1
            hereof. If Seller elects not to cure any objections specified in
            Purchaser's notice, or if Seller is unable to effect a cure prior to
            the Closing (or any date to which the Closing has been adjourned),
            Purchaser shall have the following options: (i) to accept a
            conveyance of the Property subject to the Permitted Exceptions,
            specifically including any matter objected to by Purchaser which
            Seller is unwilling or unable to cure, and without reduction of the
            Purchase Price; or (ii) to terminate this Agreement by sending
            written notice thereof to Seller, and upon delivery of such notice
            of termination, this Agreement shall terminate and the Earnest Money
            shall be returned to Purchaser, and thereafter neither party hereto
            shall have any further rights, obligations or liabilities hereunder
            except to the extent that any right, obligation or liability set
            forth herein expressly survives termination of this Agreement. If
            Seller notifies Purchaser that Seller does not intend to attempt to
            cure any title objection or objections, or if, having commenced
            attempts to cure any objection or objections, Seller later notifies
            Purchaser that Seller will be unable to effect a cure thereof,
            Purchaser shall, within ten (10) days after such notice has been
            given, notify Seller in writing whether Purchaser shall elect to
            accept the


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            conveyance under clause (i) or to terminate this Agreement under
            clause (ii). In the event Purchaser does not so timely notify Seller
            within such 10-day period, then Purchaser shall be deemed to have
            elected to terminate this Agreement under clause (ii).

II.4 Conveyance of Title. As a condition of Closing, Seller shall convey and
transfer to Purchaser, and the Title Company shall insure by a standard 1970-B
ALTA Owner's Policy of Title Insurance (or its equivalent) (the "Title Policy"),
at Purchaser's sole cost, good and marketable title to the Property (as defined
in such Title Policy), in the full amount of the Purchase Price (at such rates
as Purchaser may negotiate with the Title Company), in the name of Purchaser or
Purchaser's designee, and with such endorsements as Purchaser shall reasonably
require and which the Title Company shall agree to issue to Purchaser prior to
the Title Exam Deadline (all of which shall be at Purchaser's sole expense).
Notwithstanding anything contained herein to the contrary, the Property shall be
conveyed subject only to the following matters, which shall be deemed to be
Permitted Exceptions:

      (1) the rights of Tenants, as tenants only, under the Leases and any new
      Leases entered into between the Effective Date and Closing and, where
      required, approved by Purchaser in accordance with the terms of this
      Agreement;

      (2) the lien of all ad valorem real estate taxes and assessments not yet
      due and payable as of the date of Closing, subject to adjustment as herein
      provided;

      (3) local, state and federal laws, ordinances or governmental regulations,
      including but not limited to, building and zoning laws, ordinances and
      regulations, now or hereafter in effect relating to the Property; and

      (4) items as shown on the Title Commitment or the Survey which are not
      objected to by Purchaser or which are waived by Purchaser in accordance
      with Sections 2.3 or 2.5 hereof.

II.5 Pre-Closing "Gap" Title Defects. Whether or not Purchaser shall have
furnished to Seller any notice of title objections pursuant to the foregoing
provisions of this Section 2, Purchaser may, at or prior to Closing, notify
Seller in writing of any objections to title first raised by the Title Company
or the Surveyor between (a) the date which is the earlier of (i) the effective
date of Purchaser's Title Commitment referred to above or (ii) the expiration of
the Inspection Period, and (b) the date on which the transaction contemplated
herein is scheduled to close. With respect to any objections to title set forth
in such notice, Seller shall have the same option to cure and Purchaser shall
have the same option to accept title subject to such matters or to terminate
this Agreement as those which apply to any notice of objections made by
Purchaser before the expiration of the Inspection Period. If Seller elects to
attempt to cure any such matters, the date for Closing shall be automatically
extended by a reasonable additional time to effect such a cure, but in no event
shall the extension exceed thirty (30) days after the date for Closing set forth
in


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Section 4.1 hereof.

                                            65535RT65535CLE IIIINSPECTION PERIOD

III.1 Right of Inspection.

      (a)   During the period beginning upon the Effective Date and ending at
            5:00 p.m. Eastern time on June 30, 1999, with time being of the
            essence thereto (such period hereinafter referred to as the
            "Inspection Period"), Purchaser shall have the right to make a
            physical inspection of the Property and to examine at such place or
            places at the Property, in the offices of the property manager or
            elsewhere as the same may be located, any operating files maintained
            by Seller or its property manager in connection with the leasing,
            maintenance and/or management of the Property, including, without
            limitation, the Leases, lease files, Operating Agreements, insurance
            policies, bills, invoices, receipts and other general records
            relating to the income and expenses of the Property, correspondence,
            surveys, plans and specifications, warranties for services and
            materials provided to the Property, environmental audits and similar
            materials, but excluding materials not directly related to the
            leasing, maintenance and/or management of the Property such as,
            without limitation, Seller's internal memoranda, financial
            projections, budgets, appraisals, accounting and tax records and
            similar proprietary, elective or confidential information. Purchaser
            understands and agrees that any on-site inspections of the Property
            shall be conducted upon at least twenty-four (24) hours' prior
            written notice to Seller and in the presence of Seller or its
            representative. Such physical inspection shall not unreasonably
            interfere with the use of the Property by Seller or its tenants nor
            shall Purchaser's inspection damage the Property in any respect.
            Such physical inspection shall not be invasive in any respect
            (unless Purchaser obtains Seller's prior written consent, which
            consent shall not be unreasonably withheld or delayed), and in any
            event shall be conducted in accordance with standards customarily
            employed in the industry and in compliance with all governmental
            laws, rules and regulations. Seller acknowledges that Purchaser may
            request the right to conduct certain customary invasive tests with
            respect to testing the environmental condition of the Property.
            During the Inspection Period and at all times prior to Closing,
            Purchaser, its agents and contractors, shall have reasonable access
            to the Property and other information pertaining thereto in the
            possession or within the control of Seller or its property manager
            for the purpose of performing such studies, tests, borings,
            investigations and inspections as Purchaser shall deem necessary or
            desirable (it being understood that physical testing shall require
            Seller's prior written approval, which approval shall not be
            unreasonably withheld or delayed). Following each entry by Purchaser
            with respect to inspections and/or tests on the Property, Purchaser
            shall restore the Property to a condition which is as near to its
            original condition as existed prior to any such inspections and/or
            tests. Except as


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            specifically set forth in Section 5.3, Purchaser's right of
            inspection and the exercise of such right shall not constitute a
            waiver by Purchaser of a breach of any representation, warranty,
            covenant or agreement of Seller which might, or should, have been
            disclosed by such inspection.

      (b)   Seller shall cooperate with Purchaser in Purchaser's due diligence
            but Seller shall not be obligated to incur any liability or expense
            in connection therewith. Purchaser shall not contact any tenants of
            the Property or any governmental or quasi-governmental authorities
            without obtaining Seller's prior written consent (which consent
            shall not be unreasonably withheld or delayed), and Purchaser and
            its agents shall not disrupt Seller's or Seller's tenants'
            activities on the Property. Seller acknowledges that Purchaser shall
            require contact with such parties prior to the expiration of the
            Inspection Period in order to complete its due diligence. Purchaser
            agrees to indemnify against and hold Seller harmless from any claim
            for liabilities, costs, expenses (including reasonable attorneys'
            fees actually incurred by Seller or Seller's agents or management
            company), damages or injuries to the extent arising out of, or
            resulting from any acts or omissions of Purchaser or Purchaser's
            agents in connection with the inspection of the Property by
            Purchaser or its agents (but the foregoing indemnity shall not apply
            to any claims arising out of, or resulting from, the discovery by
            Purchaser of any existing environmental conditions or matters).
            Notwithstanding anything to the contrary in this Agreement,
            Purchaser's obligation to indemnify Seller and hold Seller harmless
            shall survive Closing or any termination of this Agreement. All
            inspections shall occur at reasonable times agreed upon by Seller
            and Purchaser.

III.2 Right of Termination. Seller agrees that in the event Purchaser determines
(such determination to be made in Purchaser's sole discretion) that the Property
is not suitable for its purposes, or for any reason or for no reason, Purchaser
shall have the right to terminate this Agreement by giving written notice
thereof to Seller prior to the expiration of the Inspection Period. If Purchaser
or Purchaser's attorneys shall give or fail to give such notice of termination
prior to expiration of the Inspection Period, then this Agreement shall
terminate and the Earnest Money shall be returned to Purchaser. Time is of the
essence with respect to the provisions of this Section 3.2.

                                                       65535RT65535CLE IVCLOSING

IV.1 Time and Place. The consummation of the transaction contemplated hereby
("Closing") shall be held at the offices of Rudnick & Wolfe, 1201 New York
Avenue, N.W., Penthouse, Washington, D.C., at 10:30 a.m. on July 15, 1999, or
such earlier date to which Seller and Purchaser may agree. At Closing, Seller
and Purchaser shall perform the obligations set forth in, respectively, Section
4.2 and Section 4.3, the performance of which obligations shall be concurrent
conditions. Notwithstanding anything in this Section 4.1 to the contrary, the
parties agree to use commercially reasonable efforts to pre-close the
transaction contemplated hereby


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(i.e., sign documents into escrow) on the business day immediately preceding the
then-scheduled date of Closing.

IV.2 Seller's Obligations at Closing. At Closing, Seller shall:

      (1) deliver to Purchaser a duly executed special warranty deed with a
      covenant of further assurances in recordable form (the "Deed"), conveying
      the Land and Improvements, subject only to the Permitted Exceptions;

      (2) deliver to Purchaser a duly executed bill of sale conveying the
      Personal Property without warranty of title or use and without warranty,
      expressed or implied, as to merchantability and fitness for any purpose;

      (3) deliver to Purchaser all original Leases and Lease files (or complete
      copies of such Leases or other documents where such documents are not in
      Seller's, Lend Lease's (as defined below) or Seller's management company's
      possession) and assign to Purchaser, and Purchaser shall assume from and
      after Closing, the landlord/lessor interest in and to the Leases by duly
      executed assignment and assumption agreement in the form attached to this
      agreement as Exhibit F;

      (4) deliver to Purchaser all original Operating Agreements as well as all
      other documents referred to herein (or complete copies of such Operating
      Agreements or other documents where such documents are not in Seller's or
      Seller's management company's possession) and to the extent assignable,
      assign to Purchaser, and Purchaser shall assume from and after Closing,
      Seller's interest in the Operating Agreements and the other Intangibles by
      duly executed assignment and assumption agreement;

      (5) deliver to Purchaser all original Tenant Estoppels (as such term is
      defined in Section 5.4(b) hereof) as are in Seller's possession.
      Notwithstanding anything contained in this Agreement to the contrary, in
      no event shall Seller be liable to Purchaser for, or deemed to be in
      default hereunder by reason of, its failure to obtain any Tenant Estoppel
      which Seller is required to deliver to Purchaser pursuant to Section
      5.4(b) (it being understood, however, that such failure shall constitute a
      non-fulfillment of a condition precedent to Purchaser's obligation to
      close hereunder and Purchaser's remedies shall be as set forth in this
      Agreement);

      (6) join with Purchaser to execute (i) a notice in form and content
      reasonably satisfactory to Purchaser and Seller which Purchaser shall send
      to each tenant under each of the Leases (A) informing such tenant of the
      sale of the Property and of the assignment to Purchaser of Seller's
      interest in, and obligations under, the Leases (including, if applicable
      any security deposits) effective from and after the Closing, and (B)
      directing that all rent and other sums payable after the Closing under
      each such Lease shall be paid as set forth in the notice, and (ii) a
      notice in form and content reasonably satisfactory to Purchaser and Seller
      which Purchaser shall send to each vendor under each of the


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      Operating Agreements in effect at Closing informing such vendor of the
      sale of the Property and of the assignment to Purchaser of Seller's
      interest in, and obligations under, the Operating Agreements and directing
      that all sums payable after the Closing under each such Operating
      Agreement shall be paid as set forth in the notice;

      (7) deliver to Purchaser a certificate, dated as of the date of Closing
      and executed on behalf of Seller by a duly authorized officer thereof,
      stating that the representations and warranties of Seller contained in
      Section 5.1 hereof are true and correct in all material respects as of the
      date of Closing (with appropriate modifications of those representations
      and warranties made in Section 5.1 hereof to reflect any changes therein
      including without limitation any changes resulting from actions under
      Section 5.4 hereof) or identifying any representation or warranty which is
      not, or no longer is, true and correct and explaining the state of facts
      giving rise to the change. In no event shall Seller be liable to Purchaser
      for, or be deemed to be in default hereunder by reason of, any breach of
      representation or warranty which results from any change that (i) occurs
      between the Effective Date and the date of Closing and (ii) is (A)
      expressly permitted under the terms of this Agreement or (B) beyond the
      reasonable control of Seller to prevent; provided, however, that the
      occurrence of a change which is not expressly permitted in this Agreement
      shall constitute a non-fulfilment of a condition precedent to Purchaser's
      obligations to close under this Agreement, and Purchaser's remedies shall
      be as set forth in this Agreement. If, despite changes or other matters
      described in such certificate, Purchaser proceeds to the Closing and the
      Closing occurs, then Seller's representations and warranties set forth in
      this Agreement shall be deemed to have been modified by all statements
      made in such certificate;

      (8) deliver to Purchaser such evidence as Purchaser's counsel and/or the
      Title Company may reasonably require as to the authority of the person or
      persons executing documents on behalf of Seller;

      (9) deliver to Purchaser an affidavit duly executed by Seller stating that
      Seller is not a "foreign person" as defined in the Federal Foreign
      Investment in Real Property Tax Act of 1980 and the 1984 Tax Reform Act;

      (10) deliver to Purchaser the Leases, Operating Agreements, Environmental
      Documents (as defined below) and licenses and permits, if any, in the
      possession of Seller or Seller's agents, together with all leasing and
      property files and records in connection with the continued operation,
      leasing and maintenance of the Property, to the extent not previously
      delivered to Purchaser. Purchaser shall cooperate with Seller for a period
      of seven (7) years after Closing in case of Seller's need in response to
      any tax audit, tax return preparation or litigation threatened or brought
      against Seller, by allowing Seller and its agents or representatives
      access, upon reasonable advance notice (which notice shall identify the
      nature of the information sought by Seller), and at reasonable times to
      examine and make copies of any and all instruments, files and records
      related to the


                                       10
<PAGE>

      period of Seller's ownership of the Property and which Seller has
      delivered to Purchaser at Closing, which right shall survive the Closing;

      (11) deliver to Purchaser possession and occupancy of the Property,
      subject to the Permitted Exceptions;

      (12) deliver such additional documents as shall be reasonably required to
      consummate the transaction expressly contemplated by this Agreement, which
      additional documents may include transfer and recordation tax declarations
      and other tax certificates; and

      (13) deliver an affidavit (and such other documents or instruments
      reasonably required by the Title Company) executed by Seller (and in form
      and substance reasonably satisfactory to Seller and Seller's counsel) (i)
      certifying against any work done or supplies delivered to the Property
      which might be grounds for a materialman's or mechanic's lien under or
      pursuant to applicable law, in form sufficient to enable the Title Company
      to delete any exception to any such lien, and (ii) which the Title Company
      may require to eliminate the pre-printed standard exceptions in the Title
      Policy;

      (14) deliver such transfer and other tax declarations and returns and
      information returns, duly executed and sworn to by Seller as may be
      required of Seller by law in connection with the conveyance of the
      Property to Purchaser (including, but not limited to, Internal Revenue
      Service forms, if required);

      (15) execute a closing statement setting forth the Purchase Price and all
      adjustments and prorations;

      (16) deliver an updated Schedule 4.4(b)(8) (delinquent rents);

      (17) deliver an updated Schedule 5.1(s) (Rent Roll);

      (18) deliver to Purchaser any letters of credit given by Tenants as
      Security Deposits, and if requested by Purchaser, Seller shall execute
      such transfer instruments in form and substance as may be required by the
      issuer of such letters of credit in connection with the transfer of such
      letters of credit to Purchaser; and

      (19) such other documents as are required under this Agreement to be
      delivered by Seller at Closing.

IV.3 Purchaser's Obligations at Closing. At Closing, Purchaser shall:

      (1) pay to Seller the full amount of the Purchase Price, as increased or
      decreased by prorations and adjustments as herein provided, in immediately
      available wire transferred federal funds pursuant to Section 1.5 above, it
      being agreed that at Closing the Earnest


                                       11
<PAGE>

      Money shall be delivered to Seller and applied towards payment of the
      Purchase Price, and it being further understood that Seller shall receive
      such proceeds at its bank account no later than 3:00 p.m. Eastern time on
      the date of Closing, failing which the pro-rations shall be redetermined
      to coincide with the date on which said funds are received prior to 3:00
      p.m. Eastern time (time being of the essence with respect to this
      subparagraph);

      (2) join Seller in execution of the instruments described in Sections
      4.2(c), 4.2(d), and 4.2(f) above;

      (3) deliver to Seller a letter duly executed by Purchaser, confirming that
      Purchaser is not acquiring the Property with the assets of an employee
      benefit plan as defined in Section 3(3) of the Employee Retirement Income
      Security Act of 1974 ("ERISA"), and, if Purchaser is unable or unwilling
      to make such a representation, then Purchaser shall be deemed to be in
      default hereunder, and Seller shall have the right to terminate this
      Agreement and to receive and retain the Earnest Money;

      (4) deliver to Seller such evidence as Seller's counsel and/or the Title
      Company may reasonably require as to the authority of the person or
      persons executing documents on behalf of Purchaser; and

      (5) deliver such additional documents as shall be reasonably required to
      consummate the transaction contemplated by this Agreement.

IV.4 Credits and Prorations.

      (1) The following shall be apportioned with respect to the Property as of
      12:01 a.m., on the day of Closing, as if Purchaser were vested with title
      to the Property during the entire day upon which Closing occurs:

            (1)   rents, if any, as and when collected (the term "rents" as used
                  in this Agreement includes all payments due and payable by
                  tenants under the Leases);

            (2)   taxes (including personal property taxes on the Personal
                  Property) and assessments levied against the Property;

            (3)   payments under the Operating Agreements;

            (4)   gas, electricity, water, sewer and other utility charges in
                  connection with the Property for which Seller is liable, if
                  any, such charges to be apportioned at Closing on the basis of
                  the most recent meter reading occurring prior to Closing (and
                  Seller shall use commercially reasonable efforts to cause the
                  utilities to read the meters as close as possible to the date
                  of Closing); and


                                       12
<PAGE>

            (5)   any other operating expenses or other items pertaining to the
                  Property which are customarily prorated between a purchaser
                  and a seller in the area in which the Property is located.

      (2) Notwithstanding anything contained in the foregoing provisions:

            (1)   At Closing, Seller shall credit to the account of Purchaser
                  the amount of all cash security deposits held by Seller, $608
                  (which represents an additional security deposit for Belay &
                  Belay Investment, Inc.) and any interest on such security
                  deposits if and only to the extent required by the applicable
                  Lease.

            (2)   Any taxes paid at or prior to Closing shall be prorated based
                  upon the amounts actually paid. If taxes and assessments for
                  the current year have not been paid before Closing, Seller
                  shall be charged at Closing an amount equal to that portion of
                  such taxes and assessments (together with interest and
                  penalties thereon) which relates to the period before Closing
                  and Purchaser shall pay the taxes and assessments prior to
                  their becoming delinquent. Any such apportionment made with
                  respect to a tax year for which the tax rate or assessed
                  valuation, or both, have not yet been fixed shall be based
                  upon the tax rate and/or assessed valuation last fixed. To the
                  extent that the actual taxes and assessments for the current
                  year differ from the amount apportioned at Closing, the
                  parties shall make all necessary adjustments by appropriate
                  payments between themselves following Closing.

            (3)   Charges referred to in Section 4.4(a) above which have been
                  contracted for by a Tenant to a third party and are payable by
                  such Tenant directly to said third party shall not be
                  apportioned hereunder, and Purchaser shall accept title
                  subject to any of such charges unpaid and Purchaser shall look
                  solely to the tenant responsible therefor for the payment of
                  the same.

            (4)   Seller shall receive the entire advantage of any discounts for
                  the prepayment by it of any taxes, water rates or sewer rents.

            (5)   As to gas, electricity and other utility charges referred to
                  in Section 4.4(a)(iv) above, Seller may on notice to Purchaser
                  elect to pay one or more of all of said items accrued to the
                  date hereinabove fixed for apportionment directly to the
                  person or entity entitled thereto, and to the extent Seller so
                  elects, such item shall not be apportioned hereunder, and
                  Seller's obligation to pay such item directly in such case
                  shall survive the Closing.

            (6)   The Personal Property is included in this sale, without
                  further charge.


                                       13
<PAGE>

            (7)   If (i) Purchaser approves any new Lease, or the renewal or
                  extension of an existing Lease which is not provided for
                  thereunder, which approval includes an approval of the costs
                  to be incurred by the landlord on account thereof, or (ii) a
                  Tenant exercises, after the Effective Date, a renewal or
                  extension of an existing Lease pursuant to a right set forth
                  therein, which exercise requires the landlord to incur certain
                  costs on account thereof, then Purchaser shall be responsible
                  for such costs and Seller shall have no responsibility
                  therefor. If, as of the date of Closing, Seller shall have
                  paid any costs for which Purchaser is responsible pursuant to
                  the foregoing sentence, Purchaser shall reimburse Seller
                  therefor at Closing. The provisions of this Section shall
                  survive the Closing.

            (8)   All moneys received from Tenants from and after the date of
                  Closing shall belong to Purchaser and shall be applied by
                  Purchaser to current rents and other charges under the Leases.
                  After application of such moneys to current rents and charges,
                  Purchaser agrees to remit to Seller any excess amounts paid by
                  a Tenant to the extent that such Tenant was in arrears in the
                  payment of rent prior to the Closing. Attached hereto as
                  Schedule 4.4(b)(8) is a schedule of delinquent rents as of the
                  Effective Date, which schedule shall be updated as of the date
                  of Closing.

            (9)   At the Closing, Seller shall deliver to Purchaser a list of
                  additional rent, however characterized, under each Lease,
                  including without limitation, real estate taxes, electrical
                  charges, utility costs and operating expenses (collectively,
                  "Additional Rents") billed to Tenants for the calendar year in
                  which the Closing occurs (both on a monthly basis and in the
                  aggregate), the basis for which the monthly amounts are being
                  billed and the amounts incurred by Seller on account of the
                  components of Additional Rents for such calendar year. Upon
                  the reconciliation by Purchaser of the Additional Rents billed
                  to Tenants, and the amounts actually incurred for such
                  calendar year, Seller and Purchaser shall be liable for
                  overpayments of Additional Rents, and shall be entitled to
                  payments from Tenants, as the case may be, on a pro rata basis
                  based upon each party's period of ownership during such
                  calendar year. In addition, Seller has advised Purchaser that
                  Brooks Brothers, Inc., is obligated to pay percentage rent in
                  accordance with its lease, and upon receipt by Purchaser of
                  any percentage rent which pertains to the period of time prior
                  to Closing, Purchaser shall promptly remit to Seller its
                  proportionate share thereof.

            (10)  With respect to the ongoing tenant improvement work being
                  performed for Radio Free Europe, Seller shall provide to
                  Purchaser at Closing a credit in the amount of any sums
                  remaining to be paid by Seller pursuant to such


                                       14
<PAGE>

                  tenants' leases. With respect to the ongoing tenant
                  improvement work being performed for Joseph M. Del Balzo,
                  Seller shall credit to Purchaser at Closing an amount equal to
                  120% of any sums outstanding for such work as of Closing, and
                  the unused portion of such credit shall be reimbursed to
                  Seller promptly after completion and acceptance by Joseph M.
                  Del Balzo of the tenant improvement work for such tenant. The
                  amount of the credit due on account of such work shall be
                  based on a letter from the contractor setting forth the
                  amounts owed to it. The credit shall also include amounts due
                  for the construction management fee for such work. With
                  respect to Seller's obligations to such tenants for the
                  aforesaid tenant improvement work, Seller shall provide to
                  Purchaser at Closing such written documentation as Purchaser
                  may request for the purpose of establishing the amounts
                  remaining to be paid to such tenants in connection with such
                  work, Seller acknowledging that Purchaser is requesting the
                  estoppel from Radio Free Europe to set forth the amount still
                  due.

      (3) Any errors in calculations or adjustments shall be corrected or
      adjusted as soon as practicable after the Closing. The provisions of this
      Section 4.4 shall survive Closing.

IV.5 Closing Costs. Seller shall pay: (a) the fees of any counsel representing
it in connection with this transaction; (b) one-half (1/2) of any escrow fee
which may be charged by the Escrow Agent or Title Company; (c) one-half (1/2) of
any transfer tax, recordation tax, grantor's tax, documentary stamp tax or
similar tax which becomes payable by reason of the transfer of the Property; (d)
the customary fees for recording the deed conveying the Property to Purchaser;
and (e) all costs incurred to repay or satisfy all liens as specifically
required by Section 2.3. Purchaser shall: (u) pay the fees of any counsel
representing Purchaser in connection with this transaction; (v) pay the premium
for the Title Policy to be issued to Purchaser by the Title Company at Closing;
(w) pay for the cost of changes to the Survey requested by Purchaser; (x) pay
one-half (1/2) of any transfer tax, recordation tax, grantor's tax, documentary
stamp tax or similar tax which becomes payable by reason of the transfer of the
Property; and (y) pay one-half (1/2) of any escrow fees charged by the Escrow
Agent or Title Company. All other costs and expenses incident to this
transaction and the closing thereof shall be paid by the party incurring such
costs and expenses. The provisions of this Section 4.5 shall survive the Closing
or any early termination of this Agreement.

IV.6 Conditions Precedent to Obligation of Purchaser. The obligation of
Purchaser to consummate the transaction hereunder shall be subject to the
fulfillment on or before the date of Closing of all of the following conditions,
any or all of which may be waived by Purchaser in its sole discretion:

      (1) Seller shall have delivered to Purchaser all of the items required to
      be delivered to Purchaser pursuant to the terms of this Agreement,
      including but not limited to, those


                                       15
<PAGE>

      provided for in Section 4.2.

      (2) All of the representations and warranties of Seller contained in this
      Agreement shall be true and correct in all material respects as of the
      date of Closing.

      (3) Seller shall have performed and observed, in all material respects,
      all covenants and agreements of this Agreement to be performed and
      observed by Seller as of and to the date of Closing.

      (4) The Title Company shall be unconditionally prepared to issue to
      Purchaser a Title Policy which meets the requirements of this Agreement.

      (5) The Property shall be in substantially the same condition as exists as
      of the last day of the Inspection Period, subject to (i) ordinary wear and
      tear, and (ii) the provisions of Article VII, it being understood that
      Seller shall not be required to replace any building systems or make any
      capital improvements except as expressly required by this Agreement.

      (f) Zuckerman, Spaeder, Goldstein, Taylor & Kolker ("Zuckerman Spaeder")
      shall have entered into a written and binding agreement in form and
      substance reasonably satisfactory to Purchaser identifying the expansion
      space on the 5th floor which Zuckerman Spaeder will occupy, which space
      shall be unoccupied and legally allowed to be occupied; such agreement
      shall also provide for a renewal of the space currently occupied by
      Zuckerman Spaeder on the 8th floor, and shall provide that the term of the
      expansion space and the renewal space shall be coterminous with the term
      of the balance of the space occupied by Zuckerman Spaeder at the Property.
      Purchaser shall have the right to reasonably approve the configuration of
      the expansion space identified by Zuckerman Spaeder, and Purchaser shall
      not be deemed to be unreasonable if the lineal footage along Connecticut
      Avenue identified by Zuckerman Spaeder is increased by more that 5% from
      the space plan annexed hereto as Exhibit H. The remaining vacant space on
      the fifth floor shall be reasonably capable of being separately demised
      and leased in the ordinary course of business, shall be reasonably
      appropriate for office use, and shall contain not less than 5,476 square
      feet. Such agreement shall set forth Zuckerman Spaeder's agreement on its
      rent and any tenant improvement allowances for the expansion space, and
      the rent for the renewal space during the renewal term, and shall
      specifically acknowledge that such agreement satisfies Zuckerman Spaeder's
      expansions rights under its Lease. At Closing Purchaser shall receive a
      credit from Seller towards the Purchase Price equal to the sum of (i),
      (ii) and (iii):

            (i)   an amount equal to $6.32 multiplied by the number of square
                  feet remaining on the 5th floor following approval by
                  Purchaser of the expansion space on such floor to be occupied
                  by Zuckerman Spaeder, further multiplied by 5 (reflecting an
                  agreed upon assumed 5 year term);


                                       16
<PAGE>

                  plus

            (ii)  the sum of (A) with respect to the expansion space on the
                  fifth floor, the positive difference between $31.32 per square
                  foot of space to be leased by Zuckerman Spaeder and the per
                  square foot fixed rent to be paid by Zuckerman Spaeder during
                  the first year of the expansion term, multiplied by the square
                  footage of such expansion space and further multiplied by the
                  annualized term of the expansion, plus (B) with respect to the
                  renewal space on ---- the eighth floor, the positive
                  difference between $31.32 per square foot of space to be
                  leased by Zuckerman Spaeder on the eighth floor and the per
                  square foot fixed rent to be paid by Zuckerman Spaeder during
                  the first year of the renewal term, multiplied by the square
                  footage of such renewal space and further multiplied by the
                  annualized term of the renewal; plus

            (iii) the sum of the amount, if any, by which the tenant improvement
                  allowance (including any sprinklering costs) for Zuckerman
                  Spaeder's fifth floor space exceeds $20 per square foot,
                  multiplied by the square footage of such expansion space, plus
                  the amount, if any, by which the tenant improvement allowance
                  (including any sprinklering costs) for Zuckerman Spaeder's
                  eighth floor space exceeds $10 per square foot, multiplied by
                  the square footage of such renewal space. In the event that
                  the agreement with Zuckerman Spaeder requires that the
                  landlord under Zuckerman Spaeder's Lease is to perform the
                  tenant improvement work, then, notwithstanding anything to the
                  contrary contained in this clause (f)(iii), Purchaser and
                  Seller shall mutually agree upon an amount that is equal to
                  150% of the estimated cost of such tenant improvement work
                  (including a construction management fee), which amount shall
                  be held in escrow pursuant to an escrow agreement mutually
                  satisfactory to Purchaser and Seller, and Purchaser shall not
                  be entitled to a credit pursuant to this clause (iii). The
                  cost of Zuckerman Spaeder's tenant improvement work shall be
                  paid from such escrow account, and any balance remaining after
                  the completion of such work shall promptly be paid to Seller.

            The provisions of this Section 4.6(f) shall survive Closing
      indefinitely.

            In lieu of the expansion rights with respect to the fifth floor,
      Seller agrees that if by 5:00 p.m. on Friday, July 2, 1999, Purchaser
      advises Seller in writing that Purchaser will approve of Zuckerman Spaeder
      occupying a portion of the 3rd floor equal to the portion which would
      otherwise be taken on the 5th floor, then if by Closing Seller delivers an
      agreement from Zuckerman Spaeder satisfying all of the terms and
      conditions set forth above but which provides for Zuckerman Spaeder
      occupying a portion of the 3rd floor rather than a portion of the 5th
      floor, and the terms and conditions of such occupancy


                                       17
<PAGE>

      provide for a fixed rent of $28.70 per square foot in the first year,
      increasing 2% per year, a 5 year term, and tenant improvement concessions
      not to exceed $20 per square foot, then Seller will credit Purchaser with
      $302,175 on account of the credits described in (i) and (ii) above and the
      credit on account of the tenant improvement allowance for the fifth floor
      as described in (iii) above.

      (6) Seller shall have paid the second half real estate brokerage
      commissions payable with respect to the lease to Joseph M. Del Balzo and
      provided Purchaser with written evidence thereof.

      (7) Radio Free Europe shall have either vacated the temporary space which
      it is occupying pursuant to that certain letter dated March 16, 1999, or
      agreed to vacate the temporary space within 15 days of the Closing, so
      long as such agreement is confirmed in writing and a copy thereof is
      provided to Purchaser.

      (8) Seller shall have delivered to Purchaser a letter from the District of
      Columbia Fire Department clarifying that there is only one (1) underground
      storage tank at the Property.

      (9) Seller shall have delivered or caused to be delivered to Purchaser a
      reliance letter from Levine-Fricke-Recon (for the Phase I Report (as
      defined below)) in form and substance reasonably satisfactory to
      Purchaser.

      (10) All Leases under which the Required Tenants (as defined below) lease
      space shall be in full force and effect.

IV.7 Conditions Precedent to Obligation of Seller. The obligation of Seller to
consummate the transaction hereunder shall be subject to the fulfillment on or
before the date of Closing of all of the following conditions, any or all of
which may be waived by Seller in its sole discretion:

      (1) Seller shall have received the Purchase Price as adjusted pursuant to
      and payable in the manner provided for in this Agreement.

      (2) Purchaser shall have delivered to Seller all of the items required to
      be delivered to Seller pursuant to the terms of this Agreement, including
      but not limited to, those provided for in Section 4.3.

      (3) All of the representations and warranties of Purchaser contained in
      this Agreement shall be true and correct in all material respects as of
      the date of Closing.

      (4) Purchaser shall have performed and observed, in all material respects,
      all covenants and agreements of this Agreement to be performed and
      observed by Purchaser as of the date of Closing.

                      65535RT65535CLE VREPRESENTATIONS, WARRANTIES AND COVENANTS


                                       18
<PAGE>

V.1 Representations and Warranties of Seller. Seller hereby makes the following
representations and warranties to Purchaser:

      (1) Organization and Authority. Seller has been duly organized and is
      validly existing under the laws of New York. Seller has the full right and
      authority to enter into this Agreement and, subject to the provisions of
      Section 10.6 hereof, to transfer all of the Property to be conveyed by
      Seller pursuant hereto and to consummate or cause to be consummated the
      transactions contemplated herein to be made by Seller. The person signing
      this Agreement on behalf of Seller is authorized to do so. This Agreement,
      when duly executed and delivered, will be the legal, valid and binding
      obligation of Seller, enforceable in accordance with the terms of this
      Agreement. The performance by Seller of its duties and obligations under
      this Agreement and the documents and instruments to be executed and
      delivered by it hereunder will not conflict with, or result in a breach
      of, or default under, any provision of any of the organizational documents
      of Seller or any agreements, instruments, decrees, judgments, injunctions,
      orders, writs, laws, rules or regulations, or any determination or award
      of any court or arbitrator, to which Seller is a party or by which its
      assets are or may be bound.

      (2) Pending Actions. To Seller's knowledge, there is no pending action,
      suit, arbitration, unsatisfied order or judgment, governmental
      investigation or proceeding against the Property or the transaction
      contemplated by this Agreement (nor, to Seller's knowledge, has any such
      matter been threatened in writing), which, if adversely determined, could
      individually or in the aggregate have an effect on the Property or any
      portion thereof or which could in any material way interfere with the
      consummation by Seller of the transaction contemplated by this Agreement
      or which is not covered by insurance.

      (3) Leases. Seller is the lessor or landlord or the successor lessor or
      landlord under the Leases. Seller has delivered to Purchaser true, correct
      and complete copies of all of the Leases and any guaranties thereof.
      Except as set forth in the Lease Schedule, there are no other leases or
      occupancy agreements affecting the Property. Except as otherwise set forth
      in the Leases, to Seller's knowledge, no presently effective rent
      concessions have been given to any tenants and no rent has been paid in
      advance by any tenants respecting a period subsequent to the Closing. No
      tenants have asserted in writing any claims, defenses or offsets to rent
      accruing from and after the date of Closing. To Seller's knowledge, except
      as disclosed to Purchaser in writing, no default, delinquency or breach
      exists on the part of any tenant, and to Seller's knowledge, no condition
      exists which, with the passage of time or the giving of notice, or both,
      will become a default. There are no defaults or breaches on the part of
      Seller, as the landlord under any Lease. In the event that any Tenant
      Estoppel delivered to Purchaser with respect to any Lease shall contain
      any statement of fact, information or other matter which is inconsistent
      with the matters stated in Seller's representations in this Section
      5.1(c), the Tenant Estoppel shall control and Seller shall have no
      liability for any claim based upon a breach of


                                       19
<PAGE>

      representation regarding such statement of fact, information or other
      matter contained in the Tenant Estoppel. Notwithstanding anything to the
      contrary contained in this Agreement, Seller does not represent or warrant
      that any particular Lease will be in force or effect at Closing or that
      the tenants under the Leases will have performed their obligations
      thereunder. The termination of any Lease prior to Closing by reason of the
      tenant's default shall not affect the obligations of Purchaser under this
      Agreement in any manner or entitle Purchaser to an abatement of or credit
      against the Purchase Price or give rise to any other claim on the part of
      Purchaser, except that such event with respect to a Required Tenant shall
      constitute a non-fulfillment of a condition precedent to Purchaser's
      obligation to close hereunder and Purchaser's remedies shall be as set
      forth in this Agreement.

      (4) Lease Brokerage. There are no lease brokerage agreements, leasing
      commission agreements or other agreements providing for payments of any
      amounts for leasing activities or procuring tenants with respect to the
      Property which will become due and payable from and after the date of
      Closing other than as disclosed in Exhibit G attached hereto and made a
      part hereof. In furtherance, and not in limitation, of the foregoing,
      Seller further represents that there are no existing agreements with
      brokers concerning expansions or renewals of existing Leases, except for
      the lease commissions payable to Fred Ezra and Trammel Crow Real Estate
      Services (and disclosed in Exhibit G), which lease commissions shall be
      paid prior to Closing pursuant to Section 4.6(g). Seller shall indemnify
      and hold harmless Purchaser from any claims arising from a breach of the
      representation set forth in this Section 5.1(d). Seller shall use
      reasonable efforts to obtain a letter from Trammel Crow Real Estate
      Services that Purchaser shall have no liability to Trammel Crow for any
      commissions or fees following the termination of its leasing agreement as
      of Closing.

      (5) No Violations. To Seller's knowledge, Seller has not received prior to
      the Effective Date any written notification from any governmental or
      public authority (i) that the Property is in violation of any applicable
      fire, health, building, use, occupancy or zoning laws where such violation
      remains outstanding and, if unaddressed, would have an adverse effect on
      the Property as currently owned and operated or (ii) that any work is
      required to be done upon or in connection with the Property, where such
      work remains outstanding and, if unaddressed, would have an adverse effect
      on the Property as currently owned and operated. In addition, to Seller's
      knowledge, there are no violations, suits, investigations or judgments
      relating to any violations of any laws, ordinances or regulations
      affecting the Property (including, without limitation, Environmental Laws
      (as hereinafter defined)), or any violations or conditions that may give
      rise thereto, and to Seller's knowledge, no agency, board, bureau,
      commission, department, office or body of any municipal, county, state or
      federal governmental unit, or any subdivision thereof, having, asserting
      or acquiring jurisdiction over all or any part of the Property or the
      management, operation, use or improvement thereof (collectively, the
      "Governmental Authorities") has notified Seller in writing that it
      contemplates the issuance thereof, and


                                       20
<PAGE>

      to Seller's knowledge, there are no outstanding orders, judgments,
      injunctions, decrees, directives or writs of any Governmental Authorities
      against or involving Seller or the Property.

      (6) Taxes and Assessments. True and complete copies of the most recent
      real estate tax bills for the Property received by Seller have been
      delivered to Purchaser. Except as disclosed to Purchaser in writing,
      Seller has not filed, and has not retained anyone to file, notices of
      protests against, or to commence action to review, real property tax
      assessments against the Property.

      (7) Condemnation. To Seller's knowledge, Seller has not received any
      written notice and, to Seller's knowledge, there are no (i) pending or
      contemplated annexation or condemnation proceedings, or private purchase
      in lieu thereof, affecting or which may affect the Property, or any part
      thereof, (ii) proposed or pending proceedings to change or redefine the
      zoning classification of all or any part of the Property, (iii) proposed
      or pending special assessments affecting the Property or any portion
      thereof, (iv) penalties or interest due with respect to real estate taxes
      assessed against the Property and (v) proposed change(s) in any road or
      grades with respect to the roads providing a means of ingress and egress
      to the Property. Seller agrees to furnish Purchaser with a copy of any
      such notice received by Seller within two (2) days after receipt.

      (8) Insurance. To Seller's knowledge, Seller has not received any written
      notice from any insurance company or board of fire underwriters of any
      defects or inadequacies in or on the Property or any part or component
      thereof that would materially and adversely affect the insurability of the
      Property or cause any material increase in the premiums for insurance for
      the Property that have not been cured or repaired or require any repairs
      or work in or to the Property.

      (9) Environmental Matters. Except as set forth in that certain Phase I
      Environmental Report prepared by Levine-Fricke-Recon and dated April 16,
      1999 (as modified by that certain letter dated June 17, 1999), a copy of
      which has been delivered to Purchaser (the "Phase I Report"), or as
      otherwise disclosed to Purchaser in writing,

            (1)   Seller has not received any Notice that any Governmental
                  Authority (as defined in Section 5.8 below) has determined
                  that there are any violations of Environmental Law (as defined
                  in Section 5.8 below) with respect to the Property.

            (2)   to Seller's knowledge, there are no Hazardous Substances (as
                  defined in Section 5.8 below) on, under, at, emanating from or
                  affecting the Property, except those in compliance with all
                  applicable Environmental Laws (as defined in Section 5.8).

            (3)   no portion of the Property has ever been used by Seller or, to
                  Seller's


                                       21
<PAGE>

                  knowledge, any current or former owner or Tenant to generate,
                  manufacture, refine, produce, treat, store, handle, dispose
                  of, transfer or process Hazardous Substances in violation of
                  any applicable Environmental Laws.

            (4)   there is no Operation and Maintenance Plan (the "O&M Plan")
                  with respect to any asbestos or asbestos-containing materials
                  at the Property.

            (5)   to Seller's knowledge, there are no above-ground storage tanks
                  or Underground Storage Tanks (as defined in Section 5.8 below)
                  at the Property (regardless of whether such tanks are
                  regulated tanks or not).

            (6)   Seller has provided Purchaser with all Environmental Documents
                  (as defined in Section 5.8 below) in the possession or control
                  of Seller, Lend Lease or Seller's property manager.

      (10) Performance of Obligations of Landlord. To Seller's knowledge, Seller
      has performed all of the obligations and observed all of the covenants
      required of the landlord under the Leases. To Seller's knowledge, all
      work, alterations, improvements or installations required to be made for
      or on behalf of all Tenants under the Leases have in all respects been
      carried out, performed and complied with, and there is no agreement with
      any Tenant for the performance of any work to be done in the future. To
      Seller's knowledge, no work has been performed at the Building which would
      require an amendment to the certificate of occupancy for the Improvements,
      and any and all work performed at the Property to the date hereof and to
      the Closing Date has been and will be in accordance with the rules, laws
      and regulations of all applicable authorities. All bills and claims for
      labor performed and materials furnished to or for the benefit of the
      Property will be paid in full on the Closing Date.

      (11) Agreements. There are no service contracts, union contracts,
      employment agreements, leasing commission or brokerage agreements or other
      agreements affecting the Property or the operation thereof, except the
      Operating Agreements. All of the Operating Agreements are unmodified and
      in full force and effect without any default or claim of default by any of
      the parties thereto. All sums currently due and payable by Seller under
      the Operating Agreements have been fully paid (or will be paid in the
      ordinary course of business) and all sums which become due and payable
      between the date hereof and the Closing Date shall be fully paid on the
      Closing Date. All of the Operating Agreements (with the exception of the
      contract with Cameo Bronze) may be terminated on not more than thirty (30)
      days notice without the payment of any fee or penalty.

      (12) Employee Contracts. There are no employees working at or in
      connection with the Property who are employed by Seller, nor are there any
      union agreements affecting


                                       22
<PAGE>

      the Property.

      (13) Bankruptcy. Seller has not made a general assignment for the benefit
      of creditors, filed any voluntary petition in bankruptcy or suffered the
      filing of any involuntary petition by Seller's creditors, suffered the
      appointment of a receiver to take possession of all, or substantially all,
      of such Seller's assets, suffered the attachment or other judicial seizure
      of all, or substantially all, of such Seller's assets, admitted in writing
      its inability to pay its debts as they come due or made an offer of
      settlement, extension or composition to its creditors generally.

      (14) Personal Property. The Personal Property listed on Exhibit B is now
      owned and will on the Closing Date be owned by Seller free and clear of
      any conditional bills of sale, chattel mortgages, security agreements or
      financing statements or other security interests of any kind. Exhibit B is
      a materially true, correct and complete listing of the Personal Property
      which Seller has used in connection with the maintenance and operation of
      the Property.

      (15) Taxes. Seller has paid all Taxes (as defined herein) due and payable
      prior to the Closing and filed all returns and reports required to be
      filed prior to the Closing with respect to the ownership and operation of
      the Property (by Seller or any predecessor entity) for which Purchaser
      could be held liable or a claim made against the Property. There are no
      audits or other proceedings by any Governmental Authorities pending or, to
      Seller's knowledge, threatened in writing with respect to the Taxes
      resulting from the ownership and operation of the Property (by it or any
      predecessor entities) for which Purchaser could be held liable or a claim
      made against the acquired property. Seller is not party to, and has no
      liability under (including liability with respect to a predecessor
      entity), any indemnification, allocation or sharing agreement with respect
      to Taxes. "Taxes" mean all federal, state, county, local, foreign and
      other taxes of any kind whatsoever (including, without limitation, income,
      profits, premium, estimated, excise, sales, use, occupancy, gross
      receipts, franchise, ad valorem, severance, capital levy, production,
      transfer, license, stamp, environmental, withholding, employment,
      unemployment compensation, payroll related and property taxes, import
      duties and other governmental charges or assessments), whether or not
      measured in whole or in part by net income, and include deficiencies,
      interest, additions to tax or interest, and penalties with respect
      thereto, and include expenses associated with contesting any proposed
      adjustment related to any of the foregoing.

      (16) No Vault Agreements or Charges. To Seller's knowledge, and except as
      may be set forth on the Title Commitment, there are no vault agreements or
      charges affecting any portion of the Property.

      (17) Security Deposits. Attached hereto as Schedule 5.1(q) is, to Seller's
      knowledge, a materially true, complete and correct listing of all Security
      Deposits held by Seller, as


                                       23
<PAGE>

      landlord, under the Leases, which Security Deposits shall be held by
      Seller in accordance with this Agreement and at Closing, shall be assigned
      to Purchaser.

      (18) No Misrepresentation. No material representation or warranty made by
      Seller and contained in this Section, and no express statement contained
      in any document, certificate, schedule or exhibit furnished or to be
      furnished by or on behalf of Seller to Purchaser contains any materially
      untrue statement of a material fact or omits to state any material fact.

      (19) Rent Roll. Attached hereto as Schedule 5.1(s) is a true, correct and
      complete rent roll for the Property setting forth the following: (i) the
      name of each Tenant; (ii) the fixed rent actually being collected; and
      (iii) the base year(s) and/or base year amount(s) for all items of rent or
      additional rent billed to each Tenant on that basis. If any Tenant
      provides a Tenant Estoppel (as set forth in Section 5.4(b)), then, to the
      extent such Tenant Estoppel covers the matters set forth in the
      immediately preceding sentence, such Tenant Estoppel shall control and the
      immediately preceding sentence shall be of no further force or effect for
      such Tenant.

V.2 Knowledge Defined.

      (a)   References to the "knowledge" of Seller shall refer only to the
            actual knowledge of the Designated Employee (as hereinafter defined)
            of Lend Lease Real Estate Investments, Inc. ("Lend Lease"), the
            manager of the Property for Seller, and shall not be construed (by
            imputation or otherwise) to refer to the knowledge of Seller, Lend
            Lease or any affiliate of either of them, to any property manager,
            or to any other officer, agent, manager, representative or employee
            of Seller or Lend Lease or any affiliate thereof or to impose upon
            such Designated Employee any duty to investigate the matter to which
            such actual knowledge, or the absence thereof, pertains; provided,
            however, that the Designated Employee has contacted Keith Lipton,
            Jones Lang LaSalle's (the property manager) representative at the
            Property, and requested that Mr. Lipton review Jones Lang LaSalle's
            files relating to the Property and the representations and
            warranties set forth in Section 5.1, and Mr. Lipton has advised the
            Designated Employee that he has no actual knowledge of any fact or
            circumstance which would cause any representation made to the
            knowledge of Seller to be false. As used herein, the term
            "Designated Employee" shall refer to Michael J. Daly, Jr. Seller
            represents and warrants that the Designated Employee is the person
            currently in the employ of either Seller or Lend Lease who possesses
            the knowledge with respect to the matters contained herein.

      (b)   References to the "knowledge" of Purchaser shall refer only to the
            actual knowledge of David Parisier ("Purchaser's Representative")
            and shall not be construed (by imputation or otherwise) to refer to
            the knowledge of Purchaser or


                                       24
<PAGE>

            any of its affiliates, or to any officer, agent, manager,
            representative or employee of Purchaser or any affiliate thereof, or
            to impose upon Purchaser's Representative any duty to investigate
            the matter to which such actual knowledge, or the absence thereof,
            pertains. Purchaser represents and warrants that the Purchaser's
            Representative is the person currently in the employ of Purchaser
            who possesses the knowledge with respect to the matters contained
            herein, and such person will be actively involved with the due
            diligence and underwriting activities with respect to Purchaser's
            acquisition of this Property through Closing. If Mr. Parisier ceases
            to be employed by Purchaser at any time prior to Closing, Purchaser
            shall immediately designate a new Purchaser's Representative.

V.3 Survival of Seller's Representations and Warranties.

      (a)   The representations and warranties of Seller set forth in Section
            5.1, as updated by the certificate of Seller to be delivered to
            Purchaser at Closing in accordance with Section 4.2(g) hereof, shall
            survive Closing for a period of two hundred seventy (270) days. No
            claim for a breach of any representation or warranty of Seller shall
            be actionable or payable (i) if the breach in question results from
            or is based on a condition, state of facts or other matter which was
            known to Purchaser's Representative prior to Closing, (ii) unless
            the valid claims for all such breaches collectively aggregate more
            than Fifty Thousand Dollars ($50,000), in which event the full
            amount of such claims shall be actionable, and (iii) unless written
            notice containing a description of the specific nature of such
            breach shall have been given by Purchaser to Seller prior to the
            expiration of said 270-day period and an action shall have been
            commenced by Purchaser against Seller within sixty (60) days after
            the termination of the survival period provided for above in this
            Section 5.3. Purchaser agrees to first seek recovery under any
            insurance policies, service contracts and Leases prior to seeking
            recovery from Seller, and Seller shall not be liable to Purchaser if
            Purchaser's claim is satisfied from such insurance policies, service
            contracts or Leases.

      (b)   As used herein, the term "Cap" shall mean an amount, in total
            aggregate, equal to $1,500,000. In no event shall Seller's aggregate
            liability to Purchaser under this Agreement, for breach of any
            representation or warranty of Seller in this Agreement or the
            certificate to be delivered by Seller at Closing pursuant to Section
            4.2(g) hereof or otherwise, exceed the amount of the Cap. During the
            foregoing 270-day period, the Value Enhancement Fund shall maintain
            $1,500,000 of assets (net of liabilities) for the purpose of
            satisfying any obligations under this Section 5.3. Notwithstanding
            anything to the contrary contained herein, Seller shall indemnify,
            defend and hold harmless Purchaser from and against all claims,
            liabilities, losses, damages, penalties and costs (including,
            without limitation, reasonable attorneys' fees) which Purchaser may
            incur as a result of Seller's failure to pay third parties or
            Seller's breach of any


                                       25
<PAGE>

            obligation or agreement with the same, which indemnification shall
            survive the Closing and shall not be subject to any monetary
            limitations.

V.4 Covenants of Seller. Seller hereby covenants with Purchaser as follows:

      (1) From the Effective Date hereof until the Closing or earlier
      termination of this Agreement, Seller shall use commercially reasonable
      efforts to operate and maintain the Property in a manner generally
      consistent with the manner in which Seller has operated and maintained the
      Property prior to the date hereof. In addition, Seller shall use
      reasonable efforts to preserve for Purchaser the relationships of Seller
      with the Tenants, suppliers and others having on-going relationships with
      the Property. Seller will complete any capital expenditure program
      currently in process or anticipated to be completed. Seller will not defer
      taking any actions or spending any of its funds, or otherwise manage the
      Property differently, due to the pending sale of the Property

      (2) Seller shall use commercially reasonable efforts (but without
      obligation to incur any cost or expense) to obtain and deliver to
      Purchaser prior to Closing, a written estoppel certificate (each, a
      "Tenant Estoppel" and collectively, the "Tenant Estoppels"), signed by
      each tenant occupying space in the Property, which Tenant Estoppels (i)
      shall be in the form of Exhibit E attached hereto and made a part hereof
      (or, alternatively, in the form, required by the applicable Lease); (ii)
      shall be dated not more than thirty (30) days prior to the date of the
      Closing; (iii) shall not contain any adverse statements (other than of a
      de minimis nature) relating to the operation or condition of the Property
      or assert a material default on the part of Seller; and (iv) shall state
      that all rent due under such Tenant's Lease has been paid through the
      month in which the Closing occurs. It shall be a condition to Closing and
      to Purchaser's obligation to perform hereunder that Seller deliver to
      Purchaser a Tenant Estoppel for each of the following tenants (the
      "Required Tenants"): Zuckerman Spaeder; Brooks Brothers; Police
      Foundation; Radio Free Europe; Association of American Law Schools; Leo
      Daly; and Joseph M. DelBalzo.

      (3) Prior to execution by Seller of any renewal or expansion of an
      existing Lease (except in connection with the exercise of a renewal or
      expansion right provided in such Lease) or of any new Lease which Seller
      wishes to execute between the Effective Date and the date of Closing,
      Seller shall submit the relevant documentation to Purchaser for
      Purchaser's approval. Prior to the expiration of the Inspection Period,
      Purchaser agrees that it shall not unreasonably withhold or delay its
      consent to any proposed lease or amendment; and after the expiration of
      the Inspection Period, Purchaser may grant or withhold its consent in its
      sole discretion. In any event, Purchaser agrees to notify Seller in
      writing within five (5) business days after its receipt thereof of either
      its approval or disapproval thereof, as well as any costs to be incurred
      by the landlord thereunder in connection therewith. In the event Purchaser
      fails to notify Seller in writing of its approval or disapproval within
      the five (5) day time period for such purpose set forth


                                       26
<PAGE>

      above, such failure shall be deemed the disapproval by Purchaser. At
      Closing, Purchaser shall reimburse Seller for any costs paid by Seller on
      account of such renewal, expansion or new Lease approved by Purchaser.

      (4) If, prior to the Closing Date, Seller shall have received from (i) any
      insurance company which issued a policy with respect to the Property, (ii)
      any board of fire underwriters or other body exercising similar functions,
      or (iii) the holder of any mortgage, any notice requiring or recommending
      any repair work to be done on the Property, Seller shall perform the same
      expeditiously and diligently at its own cost and expense prior to the
      Closing Date, but only so long as the cost thereof does not exceed $50,000
      in the aggregate.

      (5) Seller shall: (1) Promptly notify Purchaser of, and promptly deliver
      to Purchaser, a copy of any Notice which Seller may receive, on or before
      the date of Closing, from any Governmental Authority concerning a
      violation of Environmental Laws or Discharge (as defined in Section 5.8
      below) of Hazardous Substances; and (2) contemporaneously with the signing
      and delivery of this Agreement, and subsequently, promptly upon receipt by
      Seller or its representatives, deliver to Purchaser a true and complete
      copy of all Environmental Documents.

      (6) In addition to the foregoing, Seller shall not: (1) enter into any
      agreement requiring Seller to do work for any Tenant after the Closing
      Date without first obtaining the prior written consent of Purchaser; (2)
      Accept the surrender of any Service Contract or Lease, or grant any
      concession, rebate, allowance or free rent; (3) apply any Security
      Deposits with respect to any Tenant in occupancy on the Closing Date; (4)
      Renew, extend or modify any of the Operating Agreements without the prior
      written consent of Purchaser; (5) Remove any Personal Property located in
      or on the Property, except as may be required for repair and replacement.
      All replacements shall be free and clear of liens and encumbrances and
      shall be of quality at least equal to the replaced items and shall be
      deemed included in this sale, without cost or expense to Purchaser; (6)
      Cause or permit the Property, or any interest therein, to be alienated,
      mortgaged, licensed, encumbered or otherwise be transferred; or (7) cause
      or permit any new lien or encumbrance to be placed upon or against the
      Property. Seller agree to remove, or cause to be removed, at its sole cost
      and expense, any lien or encumbrance which appears of record after the
      date on which the Title Commitment was issued and is not shown on the
      Title Commitment.

      (7) Upon request of Purchaser at any time after the date hereof (but
      without any cost or expense to Seller), Seller shall assist Purchaser in
      its preparation of audited financial statements, statements of income and
      expense, and such other documentation as Purchaser may reasonably request,
      covering the period of Seller's ownership of the Property.


                                       27
<PAGE>

      (8) Up to and including the Closing Date, Seller agrees to maintain and
      keep such hazard, liability and casualty insurance policies in full force
      and effect in such amounts and covering such risks sufficiently to protect
      the Property and to protect, to a reasonable and prudent extent, the owner
      of the Property, in such amounts as are required so as not to be deemed a
      co-insurer, and for actual replacement cost, against any loss, damage,
      claim or liability.

      (9) Seller shall cancel, at its sole cost and expense, those Operating
      Agreements which Purchaser elects not to assume and which can, by their
      terms, be terminated prior to the Closing without the payment of any
      termination or other penalties or charges of any type or nature.

      (10) Seller shall permit Purchaser and its authorized representatives to
      inspect the Books and Records of its operations concerning the Property at
      all reasonable times and on reasonable advance notice. The foregoing shall
      survive the Closing.

      (11) All violations of statutes, ordinances, rules, regulations, orders,
      codes, directives or requirements affecting the Property, whether or not
      such violations are now noted in the records of or have been issued by any
      Governmental Authorities, shall be complied with by Seller prior to the
      Closing and the Property shall be conveyed free of any such violations,
      including, without limitation, violations of Environmental Laws, provided
      that the aggregate cost to Seller of complying with the foregoing shall
      not exceed $50,000. If the cost to cure said violations exceeds $50,000,
      Purchaser shall have the right to either (i) terminate this Agreement and
      receive a full refund of the Earnest Money or (ii) proceed to Closing, and
      at such event Purchaser shall receive a $50,000 credit from Seller.
      Notwithstanding the immediately preceding sentence, in the event that
      Purchaser elects to terminate this Agreement pursuant to clause (i) above,
      then Seller shall have the right to cure said violations by paying the
      entire cost to cure said violation and Purchaser and Seller shall proceed
      to Closing (and Purchaser's election to terminate this Agreement shall be
      of no force or effect).

V.5 Representations and Warranties of Purchaser. Purchaser hereby represents and
warrants to Seller:

      (1) Purchaser is not acquiring the Property with the assets of an employee
      benefit plan as defined in Section 3(3) of ERISA.

      (2) Subject to the provisions of Section 10.6 hereof, Purchaser has the
      full right, power and authority to purchase the Property as provided in
      this Agreement and to carry out Purchaser's obligations hereunder, and all
      requisite action necessary to authorize Purchaser to enter into this
      Agreement and to carry out its obligations hereunder have been, or by the
      Closing will have been, taken. The person signing this Agreement on behalf
      of Purchaser is authorized to do so.


                                       28
<PAGE>

      (3) There is no action, suit, arbitration, unsatisfied order or judgment,
      government investigation or proceeding pending against Purchaser which, if
      adversely determined, could individually or in the aggregate materially
      interfere with the consummation of the transaction contemplated by this
      Agreement.

V.6 Survival of Purchaser's Representations and Warranties. The representation
and warranties of Purchaser set forth in Section 5.5(a) shall survive Closing
and shall be a continuing representation and warranty without limitation. All
other representations and warranties of Purchaser shall survive Closing for a
period of one hundred eighty (180) days.

V.7 Covenants of Purchaser. Purchaser hereby covenants with Seller as follows:

      (1) If Purchaser, in connection with its investigation of the Property
      during the Inspection Period, inspects the Property for the presence of
      Hazardous Substances (as defined in Section 5.1(i) hereof), and if
      Purchaser terminates this Agreement during the Inspection Period, then
      Purchaser shall furnish to Seller copies of any reports received by
      Purchaser in connection with any such inspection. Purchaser hereby assumes
      full responsibility for such inspections and, except for claims based on
      representations or warranties contained in Section 5.1(i), irrevocably
      waives any claim against Seller arising from the presence of Hazardous
      Substances on the Property. If Purchaser terminates this Agreement during
      the Inspection Period, Purchaser shall also furnish to Seller copies of
      any other reports received by Purchaser relating to any other inspections
      of the Property conducted on Purchaser's behalf, if any (including,
      specifically, without limitation, any reports analyzing compliance of the
      Property with the provisions of the Americans with Disabilities Act
      ("ADA"), 42 U.S.C. ss.12101, et seq., if applicable), other than those
      reports which are confidential or proprietary in nature. The provisions of
      this Section shall survive Closing or any early termination of this
      Agreement.

      (2) Purchaser shall, at least twenty-four (24) hours prior to any entry
      onto the Property, in connection with its investigation of the Property
      during the Inspection Period, provide Seller with sufficient evidence to
      show that Purchaser and its agents or representatives who are to enter
      upon the Property are adequately covered by policies of insurance issued
      by a carrier reasonably acceptable to Seller insuring Purchaser, Seller
      and Seller's advisors and property manager against any and all liability
      arising out of Purchaser's or its agents' or representatives' entry
      (including, without limitation, any loss or damage to the Property, with
      coverage in the amount of not less than $5,000,000 per occurrence).
      Purchaser agrees that it will cause any such person accessing the Property
      to be covered by not less than $5,000,000 liability insurance insuring all
      activity and conduct of such person while exercising such right of access.
      Purchaser represents and warrants that it carries not less than $5,000,000
      general liability insurance with a contractual liability endorsement which
      insures its indemnity obligations under this Agreement, which names Seller
      and Seller's advisors and property manager of the Property as additional
      insureds thereunder. The provisions of this Section shall survive


                                       29
<PAGE>

      Closing or any early termination of this Agreement.

V.8 Environmental Definitions.

      (1) "Hazardous Substances" shall include, without limitation, any
      regulated substance, toxic substance, hazardous substance, hazardous
      waste, pollution, pollutant or contaminant, as defined or referred to in
      the "Tanks Laws" as defined below; the Resource Conservation and Recovery
      Act, as amended, 42 U.S.C. ss.6901 et seq.; the Comprehensive
      Environmental Response, Compensation and Liability Act, as amended, 42
      U.S.C. ss.9601 et seq. ("CERCLA"); the Water Pollution and Control Act, 33
      U.S.C. ss.1251 et seq.; together with any amendments thereto, regulations
      promulgated thereunder and all substitutions thereof, as well as words of
      similar purport or meaning referred to in any other applicable federal,
      state, county or municipal environmental statute, ordinance, code, rule or
      regulation, including, without limitation, lead, radon, asbestos,
      polychlorinated biphenyls, urea formaldehyde and petroleum products and
      petroleum based derivatives. Where a statute, ordinance, code, rule or
      regulation defines any of these terms more broadly than another, the
      broader definition shall apply.

      (2) "DCEHA" shall mean the District of Columbia Environmental Health
      Administrator or its successor.

      (3) "Discharge" shall mean the releasing, spilling, leaking, leaching,
      disposing, pumping, pouring, emitting, emptying, treating or dumping of
      Hazardous Substances at, into, onto or migrating from or onto the
      Property, regardless of whether the result of an intentional or
      unintentional action or omission.

      (4) "Environmental Documents" shall mean all environmental documentation
      in the possession or under the control of Seller concerning the Property,
      or its environs, including without limitation, all sampling plans, cleanup
      plans, preliminary assessment plans and reports, site investigation plans
      and reports, remedial investigation plans and reports, remedial action
      plans and reports, or the equivalent, operation and maintenance plans,
      asbestos abatement reports, sampling results, sampling result reports,
      data, diagrams, charts, maps, analysis, conclusions, quality
      assurance/quality control documentation, correspondence to or from any
      Governmental Authority, submissions to any Governmental Authority and
      directives, orders, approvals and disapprovals issued by any Governmental
      Authority.

      (5) "Environmental Laws" shall mean each and every applicable federal,
      state, county or municipal statute, ordinance, rule, regulation, order,
      code, directive or requirement, together with all successor statutes,
      ordinances, rules, regulations, orders, codes, directives or requirements,
      of any Governmental Authority in any way related to Hazardous Substances.

      (6) "Governmental Authority" shall mean the federal, state, District of
      Columbia,


                                       30
<PAGE>

      county or municipal government, or any department, agency, commission,
      bureau or other similar type body obtaining authority therefrom or created
      pursuant to any laws, ordinances, rules, regulations, orders, codes,
      directives or requirements.

      (7) "Notice" shall mean, in addition to its ordinary meaning, any written
      communication of any nature, whether in the form of correspondence,
      memoranda, order, directive or otherwise.

      (8) "Tank Laws" shall mean the D.C. Code Ann. ss.6-995.1 et seq., and the
      federal underground storage tank law (Subtitle I) of the Resource
      Conservation and Recovery Act, as amended, 42 U.S.C. ss.6901 et seq.,
      together with any amendments thereto, regulations promulgated thereunder,
      and all substitutions thereof, and any successor legislation and
      regulations.

      (9) "Underground Storage Tank" shall mean each and every "underground
      storage tank", whether or not subject to the Tank Laws, as well as the
      "monitoring system", the "leak detection system", the "discharge detection
      system" and the "tank system" associated with the "underground storage
      tank", as those terms are defined by the Tank Laws.

                                                       65535RT65535CLE VIDEFAULT

VI.1 Default by Purchaser. If the Closing shall fail to occur on account of
Purchaser's default under this Agreement, Seller shall have the right to
terminate this Agreement and to receive and retain the Earnest Money hereunder
as liquidated damages, and not as a penalty or forfeiture, as Seller's sole and
exclusive remedy under this Agreement, at law or in equity, on account of
Purchaser's default hereunder. Upon receipt of the Earnest Money by Seller, this
Agreement shall terminate and the parties shall be relieved of any further
obligations or liabilities to the other hereunder, except for any right,
obligation or liability set forth herein which expressly survives termination of
this Agreement.

VI.2 Default by Seller. In the event that Seller fails to consummate this
Agreement for any reason other than Purchaser's default or the permitted
termination of this Agreement by Seller or Purchaser as herein expressly
provided, Purchaser shall be entitled, as its sole remedy, either (a) to receive
the Earnest Money and, if Seller is in default under this Agreement,
reimbursement from Seller for Purchaser's actual third-party out-of-pocket costs
and expenses (including reasonable attorneys' fees) up to $50,000, in which
event this Agreement shall terminate and Seller shall be released from any and
all liability under this Agreement (except for those rights, obligations or
liabilities set forth in this Agreement which expressly survive termination of
this Agreement), or (b) to enforce specific performance of Seller's obligation
to execute and deliver the documents required to convey the Property to
Purchaser, it being understood and agreed that the remedy of specific
performance shall not be available to enforce any other obligation of Seller
hereunder; provided, however, provided, however, that if, as a result of any act
or


                                       31
<PAGE>

omission of Seller, Purchaser pursues, but cannot be granted, a decree of
specific performance by a court of competent jurisdiction, then, and only in
such instance, may Purchaser seek such other remedies as are available to
Purchaser at law or in equity. Such act or omission would include, by way of
example and not limitation, the conveyance of the Property to a third party, the
execution of a lease modification or amendment or new Lease (in violation of the
provisions of Section 5.4(c)) or the failure to satisfy a lien which Seller has
expressly agreed herein to satisfy and discharge. Except as expressly provided
herein, Purchaser expressly waives its rights to seek damages in the event of
Seller's default hereunder. Purchaser shall be deemed to have elected to
terminate this Agreement and receive back the Earnest Money if Purchaser fails
to file suit for specific performance against Seller in a local or Federal court
in the District of Columbia, on or before sixty (60) days following the date
upon which Closing was to have occurred.

                                                 65535RT65535CLE VIIRISK OF LOSS

VII.1 Minor Damage. In the event of loss or damage to the Property or any
portion thereof which is not "major" (as hereinafter defined), this Agreement
shall remain in full force and effect provided Seller performs any necessary
repairs or, at Seller's option, assigns to Purchaser all of Seller's right,
title and interest to any claims and proceeds Seller may have with respect to
any casualty insurance policies or condemnation awards relating to the premises
in question. In the event that Seller elects to perform repairs upon the
Property, Seller shall use reasonable efforts to complete such repairs promptly,
subject to Purchaser's reasonable supervision, and the date of Closing shall be
extended a reasonable time in order to allow for the completion of such repairs.
If Seller elects to assign a casualty claim to Purchaser, then the Purchase
Price shall be reduced by an amount equal to the deductible amount under
Seller's insurance policy. Upon Closing, full risk of loss with respect to the
Property shall pass to Purchaser.

VII.2 Major Damage. In the event of a "major" loss or damage to any portion of
the Property, Seller shall send written notice thereof to Purchaser. Purchaser
shall have ten (10) business days after its receipt of such notice from Seller
to terminate this Agreement by written notice to Seller. If Purchaser terminates
this Agreement, then the Earnest Money shall be returned to Purchaser promptly.
If Purchaser does not terminate this Agreement within such ten-day period, then
Purchaser shall be deemed to have elected to proceed with Closing, in which
event Seller shall, at Seller's option, either (a) perform any necessary
repairs, or (b) assign to Purchaser all of Seller's right, title and interest to
any claims and proceeds Seller may have with respect to any casualty insurance
policies or condemnation awards relating to the premises in question. In the
event that Seller elects to perform repairs upon the Property, Seller shall use
reasonable efforts to complete such repairs promptly and the date of Closing
shall be extended a reasonable time in order to allow for the completion of such
repairs. If Seller elects to assign a casualty claim to Purchaser, the Purchase
Price shall be reduced by an amount equal to the deductible amount under
Seller's insurance policy. Upon Closing, full risk of loss with respect to the
Property shall pass to Purchaser.

VII.3 Definition of "Major" Loss or Damage. For purposes of Sections 7.1 and
7.2, "major"


                                       32
<PAGE>

loss or damage refers to the following: (i) loss or damage to the Property or
any portion thereof such that the cost of repairing or restoring the premises in
question to a condition substantially identical to that of the premises in
question prior to the event of damage would be, in the opinion of an architect
selected by Seller and reasonably approved by Purchaser, equal to or greater
than Two Hundred Fifty Thousand and 00/100 Dollars ($250,000.00), and (ii) any
loss due to a condemnation of any portion of the Property. If Purchaser does not
give notice to Seller of Purchaser's reasons for disapproving an architect
within five (5) business days after receipt of notice of the proposed architect,
Purchaser shall be deemed to have approved the architect selected by Seller.

                                                 65535RT65535CLE VIIICOMMISSIONS

VIII.1 Brokerage Commissions. In the event the transaction contemplated by this
Agreement is consummated, but not otherwise, Seller agrees (i) to pay to Cassidy
& Pinkard/Sonnenblick-Goldman (the "Broker") at Closing a brokerage commission
pursuant to a separate written agreement between Seller and Broker and (ii) to
indemnify, defend and hold Purchaser harmless from and against any loss or
damage (including attorneys' fees) which Purchaser may suffers on account of any
claims by the Broker. Each party agrees that should any claim be made for
brokerage commissions or finder's fees by any broker or finder other than the
Broker by, through or on account of any acts of said party or its
representatives, said party will indemnify and hold the other party free and
harmless from and against any and all loss, liability, cost, damage and expense
in connection therewith. The provisions of this section shall survive Closing or
earlier termination of this Agreement.

                                       65535RT65535CLE IXDISCLAIMERS AND WAIVERS

IX.1 No Reliance on Documents. Except as expressly stated herein, Seller makes
no representation or warranty as to the truth, accuracy or completeness of any
materials, data or information delivered by Seller to Purchaser in connection
with the transaction contemplated hereby. Purchaser acknowledges and agrees that
all materials, data and information delivered by Seller to Purchaser in
connection with the transaction contemplated hereby are provided to Purchaser as
a convenience only and that any reliance on or use of such materials, data or
information by Purchaser shall be at the sole risk of Purchaser, except as
otherwise expressly stated herein. Without limiting the generality of the
foregoing provisions, Purchaser acknowledges and agrees that, except as to
Purchaser's right to rely upon any environmental or other report to the extent
that the person or entity which prepared the report authorizes Purchaser to rely
thereon, (a) any environmental or other report with respect to the Property
which is delivered by Seller to Purchaser shall be for general informational
purposes only, (b) Purchaser shall not have any right to rely on any such report
delivered by Seller to Purchaser, but rather will rely on its own inspections
and investigations of the Property and any reports commissioned by Purchaser
with respect thereto, and (c) neither Seller, any affiliate of Seller nor the
person or entity which prepared any such report delivered by Seller to Purchaser
shall have any liability to Purchaser for any inaccuracy in or omission from any
such report.


                                       33
<PAGE>

IX.2 DISCLAIMERS. EXCEPT AS EXPRESSLY SET FORTH IN THIS AGREEMENT (WHICH
EXCEPTION SHALL MODIFY ALL OF THE STATEMENTS SET FORTH IN THIS SECTION 9.2), IT
IS UNDERSTOOD AND AGREED THAT SELLER IS NOT MAKING AND HAS NOT AT ANY TIME MADE
ANY WARRANTIES OR REPRESENTATIONS OF ANY KIND OR CHARACTER, EXPRESSED OR
IMPLIED, WITH RESPECT TO THE PROPERTY, INCLUDING, BUT NOT LIMITED TO, ANY
WARRANTIES OR REPRESENTATIONS AS TO HABITABILITY, MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE, TITLE (OTHER THAN SELLER'S LIMITED WARRANTY OF TITLE TO BE
SET FORTH IN THE DEED), ZONING, TAX CONSEQUENCES, LATENT OR PATENT PHYSICAL OR
ENVIRONMENTAL CONDITION, UTILITIES, OPERATING HISTORY OR PROJECTIONS, VALUATION,
GOVERNMENTAL APPROVALS, THE COMPLIANCE OF THE PROPERTY WITH GOVERNMENTAL LAWS,
THE TRUTH, ACCURACY OR COMPLETENESS OF THE PROPERTY DOCUMENTS OR ANY OTHER
INFORMATION PROVIDED BY OR ON BEHALF OF SELLER TO PURCHASER, OR ANY OTHER MATTER
OR THING REGARDING THE PROPERTY. PURCHASER ACKNOWLEDGES AND AGREES THAT UPON
CLOSING SELLER SHALL SELL AND CONVEY TO PURCHASER AND PURCHASER SHALL ACCEPT THE
PROPERTY "AS IS, WHERE IS, WITH ALL FAULTS", EXCEPT TO THE EXTENT EXPRESSLY
PROVIDED OTHERWISE IN THIS AGREEMENT. PURCHASER HAS NOT RELIED AND WILL NOT RELY
ON, AND SELLER IS NOT LIABLE FOR OR BOUND BY, ANY EXPRESSED OR IMPLIED
WARRANTIES, GUARANTIES, STATEMENTS, REPRESENTATIONS OR INFORMATION PERTAINING TO
THE PROPERTY OR RELATING THERETO (INCLUDING SPECIFICALLY, WITHOUT LIMITATION,
PROPERTY INFORMATION PACKAGES DISTRIBUTED WITH RESPECT TO THE PROPERTY) MADE OR
FURNISHED BY SELLER, THE MANAGER OF THE PROPERTY, OR ANY REAL ESTATE BROKER OR
AGENT REPRESENTING OR PURPORTING TO REPRESENT SELLER, TO WHOMEVER MADE OR GIVEN,
DIRECTLY OR INDIRECTLY, ORALLY OR IN WRITING, UNLESS SPECIFICALLY SET FORTH IN
THIS AGREEMENT. PURCHASER REPRESENTS TO SELLER THAT PURCHASER HAS CONDUCTED, OR
WILL CONDUCT PRIOR TO CLOSING, SUCH INVESTIGATIONS OF THE PROPERTY, INCLUDING
BUT NOT LIMITED TO, THE PHYSICAL AND ENVIRONMENTAL CONDITIONS THEREOF, AS
PURCHASER DEEMS NECESSARY TO SATISFY ITSELF AS TO THE CONDITION OF THE PROPERTY
AND THE EXISTENCE OR NONEXISTENCE OR CURATIVE ACTION TO BE TAKEN WITH RESPECT TO
ANY HAZARDOUS OR TOXIC SUBSTANCES ON OR DISCHARGED FROM THE PROPERTY, AND WILL
RELY SOLELY UPON SAME AND NOT UPON ANY INFORMATION PROVIDED BY OR ON BEHALF OF
SELLER OR ITS AGENTS OR EMPLOYEES WITH RESPECT THERETO, OTHER THAN SUCH
REPRESENTATIONS, WARRANTIES AND COVENANTS OF SELLER AS ARE EXPRESSLY SET FORTH
IN THIS AGREEMENT. UPON CLOSING, PURCHASER SHALL ASSUME (AS BETWEEN PURCHASER
AND SELLER) THE RISK THAT ADVERSE MATTERS, INCLUDING BUT NOT LIMITED TO,


                                       34
<PAGE>

CONSTRUCTION DEFECTS AND ADVERSE PHYSICAL AND ENVIRONMENTAL CONDITIONS, MAY NOT
HAVE BEEN REVEALED BY PURCHASER'S INVESTIGATIONS, AND PURCHASER, UPON CLOSING,
SHALL BE DEEMED TO HAVE WAIVED, RELINQUISHED AND RELEASED SELLER (AND SELLER'S
OFFICERS, DIRECTORS, SHAREHOLDERS, EMPLOYEES AND AGENTS) FROM AND AGAINST ANY
AND ALL CLAIMS, DEMANDS, CAUSES OF ACTION (INCLUDING CAUSES OF ACTION IN TORT),
LOSSES, DAMAGES, LIABILITIES, COSTS AND EXPENSES (INCLUDING ATTORNEYS' FEES AND
COURT COSTS) OF ANY AND EVERY KIND OR CHARACTER, KNOWN OR UNKNOWN, WHICH
PURCHASER MIGHT HAVE ASSERTED OR ALLEGED AGAINST SELLER (AND SELLER'S OFFICERS,
DIRECTORS, SHAREHOLDERS, EMPLOYEES AND AGENTS) AT ANY TIME BY REASON OF OR
ARISING OUT OF ANY LATENT OR PATENT CONSTRUCTION DEFECTS OR PHYSICAL CONDITIONS,
VIOLATIONS OF ANY APPLICABLE LAWS (INCLUDING, WITHOUT LIMITATION, ANY
ENVIRONMENTAL LAWS) AND ANY AND ALL OTHER ACTS, OMISSIONS, EVENTS, CIRCUMSTANCES
OR MATTERS REGARDING THE PROPERTY, EXCEPT FOR A VIOLATION OF A REPRESENTATION OR
WARRANTY MADE BY SELLER IN THIS AGREEMENT. PURCHASER AGREES THAT SHOULD ANY
CLEANUP, REMEDIATION OR REMOVAL OF HAZARDOUS SUBSTANCES OR OTHER ENVIRONMENTAL
CONDITIONS ON THE PROPERTY BE REQUIRED AFTER THE DATE OF CLOSING, SELLER SHALL
HAVE NO RESPONSIBILITY TO PURCHASER FOR THE COST OR EXPENSE OF SUCH CLEAN-UP,
REMOVAL OR REMEDIATION.

                                                  65535RT65535CLE XMISCELLANEOUS

X.1 Confidentiality. For purposes of this Agreement and the transactions
contemplated hereunder, Seller and Purchaser agree that they and their
respective agents and representatives shall be bound by the terms and conditions
of that certain letter agreement dated March 10, 1999, between Purchaser and the
Broker (as hereinafter defined) and attachments thereto (collectively, the
"Confidentiality Agreement"), and the terms and conditions of the
Confidentiality Agreement are incorporated herein its entirety. In the event of
a breach or threatened breach of this Section 10.1 by Seller or Purchaser or
their agents or representatives, the non-breaching party shall be entitled to an
injunction restraining the breaching party or its agents or representatives from
disclosing, in whole or in part, such confidential information. Nothing herein
shall be construed as prohibiting the non-breaching from pursuing any other
available remedy at law or in equity for such breach or threatened breach. The
provisions of this Section 10.1 shall survive Closing or any early termination
of this Agreement

X.2 Public Disclosure. Prior to Closing, any release to the public of
information with respect to the sale contemplated herein or any matters set
forth in this Agreement will be made only in the form approved by Purchaser and
Seller and their respective counsel, which approval shall not be unreasonably
withheld or delayed. The provisions of this Section shall survive Closing or any
early termination of this Agreement.


                                       35
<PAGE>

X.3 Discharge of Obligations. The acceptance of the Deed by Purchaser shall be
deemed to be a full performance and discharge of every representation and
warranty made by Seller herein and every agreement and obligation on the part of
Seller to be performed pursuant to the provisions of this Agreement, except
those which are herein specifically stated to survive Closing.

X.4 Assignment. Purchaser may not assign its rights under this Agreement without
first obtaining Seller's written approval, which approval may be given or
withheld in Seller's sole discretion; provided, however, that Purchaser may
assign this Agreement to an entity which is affiliated (i) with Purchaser or
(ii) with any entity under the common control of the entity controlling
Purchaser. In the event of an assignment by Purchaser to any such entity,
Purchaser shall advise Seller prior to the Closing. Under no circumstances shall
Purchaser have the right to assign this Agreement to any person or entity owned
or controlled by an employee benefit plan if Seller's sale of the Property to
such person or entity would, in the reasonable opinion of Seller's ERISA
advisor, create or otherwise cause a "prohibited transaction" under ERISA. In
the event Purchaser assigns this Agreement or transfers any ownership interest
in Purchaser, and such assignment or transfer would make the consummation of the
transaction hereunder a "prohibited transaction" under ERISA and necessitate the
termination of this Agreement then, notwithstanding any contrary provision which
may be contained herein, Seller shall have the right to pursue any remedy
available at law or in equity as a result of such assignment or transfer. Any
transfer, directly or indirectly, of any stock, partnership interest or other
ownership interest in Purchaser without Seller's written approval, which
approval may be given or withheld in Seller's sole discretion, shall constitute
a default by Purchaser under this Agreement.

X.5 Notices. Any notice pursuant to this Agreement shall be given in writing by
(a) personal delivery, or (b) reputable overnight delivery service with proof of
delivery, or (c) United States Mail, postage prepaid, registered or certified
mail, return receipt requested, or (d) legible facsimile transmission sent to
the intended addressee at the address set forth below, or to such other address
or to the attention of such other person as the addressee shall have designated
by written notice sent in accordance herewith, and shall be deemed to have been
given either at the time of personal delivery, or, in the case of expedited
delivery service or mail, as of the date of first attempted delivery at the
address and in the manner provided herein, or, in the case of facsimile
transmission, as of the date of the facsimile transmission provided that an
original of such facsimile is also sent to the intended addressee by means
described in clauses (a), (b) or (c) above. Notices may be given by counsel for
the parties and such notices shall be deemed given by Purchaser or Seller as the
case may be. Unless changed in accordance with the preceding sentence, the
addresses for notices given pursuant to this Agreement shall be as follows:

      If to Seller:                       The Equitable Life Assurance Society
                                          of the United Statesc/o Lend Lease
                                          Real Estate Investments, Inc.


                                       36
<PAGE>

                                          600 14th Street, N.W., Suite 725
                                          Washington, D.C. 20005 Attention:
                                          Michael J. Daly, Jr. Phone: (202)
                                          783-1466Telecopy: (202) 783-1841

      with a copy to:                     Rudnick & Wolfe 1201 New York Avenue,
                                          N.W. Washington, D.C. 20005 Attention:
                                          Frederick L. Klein Phone: (202)
                                          712-7275Telecopy: (202) 712-7222

      If to Purchaser:                    c/o Mack-Cali Realty Corporation 11
                                          Commerce DriveCranford, New Jersey
                                          07016 Attention: Mitchell E. Hersh
                                          Phone: (908) 272-8000 Telecopy: (908)
                                          272-6755

                                          and

                                          c/o Mack-Cali Realty Corporation 11
                                          Commerce DriveCranford, New Jersey
                                          07016 Attention: Roger W. Thomas
                                          Phone: (908) 272-8000 Telecopy: (908)
                                          272-6755

      with a copy to:                     Pryor Cashman, Sherman & Flynn410 Park
                                          AvenueNew York, New York
                                          10022Attention: Andrew S. Levine
                                          Phone: (212) 326-0414 Telecopy: (212)
                                          326-0806

      If to Escrow Agent:                 Commonwealth Land Title Insurance
                                          Company c/o Commercial Settlements,
                                          Inc. 1413 K Street, N.W. Washington,
                                          DC 20005


                                       37
<PAGE>

                                          Attention: Stuart S. Levin
                                          Phone: (202) 312-5111 Telecopy: (202)
                                          737-4108

X.6 Binding Effect. This Agreement shall not be binding in any way upon Seller
unless and until (a) Seller shall execute and deliver the same to Purchaser, (b)
each stage of Seller's investment approval process has approved this
transaction, and (c) Seller's Investment Committee has thereafter given its
written approval thereof. If (A) Seller has not given Purchaser written notice
(the "Approval Notice") of such approvals on or before 3:00 p.m. (Eastern time)
June 30, 1999 (the "Approval Deadline"), or (B) prior to the Approval Deadline
Seller notifies Purchaser in writing that this Agreement has been disapproved by
the persons or entities referred to in clauses (b) or (c) of the preceding
sentence, then (x) this Agreement shall be deemed terminated and Purchaser shall
be entitled to the return of the Earnest Money and (y) Seller shall reimburse
Purchaser for its reasonable costs and expenses incurred up to and including the
date of such termination (including reasonable attorneys' fees), provided that
such reimbursement shall not exceed $50,000. It is understood and agreed that at
each stage of Seller's investment approval process, Seller or its investment
advisor, Lend Lease, shall each have the right, in its unfettered discretion, to
disapprove the transaction contemplated by this Agreement for any reason
whatsoever, without obligation thereafter to proceed to the next stage of
Seller's investment approval process. Seller's approval of this Agreement shall
be evidenced only by both Seller's execution of this Agreement and Seller's
sending of the Approval Notice to Purchaser prior to the Approval Deadline and,
accordingly, Purchaser acknowledges and agrees that Purchaser cannot and will
not rely upon any other statement or action of Seller or its representatives as
evidence of Seller's approval of this Agreement or the subject matter hereof.

X.7 Modifications. This Agreement cannot be changed orally, and no executory
agreement shall be effective to waive, change, modify or discharge it in whole
or in part, unless such executory agreement is in writing and is signed by the
parties against whom enforcement of any waiver, change, modification or
discharge is sought.

X.8 Tenant Notification Letters. Purchaser shall deliver to each and every
tenant of the Property under a Lease thereof a signed statement acknowledging
Purchaser's receipt and responsibility for each tenant's security deposit (to
the extent delivered by Seller to Purchaser at Closing), if any, all in
compliance with and pursuant to the applicable provisions of applicable law. The
provisions of this paragraph shall survive Closing.

X.9 Calculation of Time Periods. Unless otherwise specified, in computing any
period of time described in this Agreement, the day of the act or event after
which the designated period of time begins to run is not to be included and the
last day of the period so computed is to be included, unless such last day is a
Saturday, Sunday or legal holiday under the laws of the District of Columbia, in
which event the period shall run until the end of the next day which is


                                       38
<PAGE>

neither a Saturday, Sunday or legal holiday. The final day of any such period
shall be deemed to end at 5 p.m., local time.

X.10 Successors and Assigns. The terms and provisions of this Agreement are to
apply to and bind the permitted successors and assigns of the parties hereto.

X.11 Entire Agreement. This Agreement, including the Exhibits, contains the
entire agreement between the parties pertaining to the subject matter hereof and
fully supersedes all prior written or oral agreements and understandings between
the parties pertaining to such subject matter.

X.12 Further Assurances. Each party agrees that it will without further
consideration execute and deliver such other documents and take such other
action, whether prior or subsequent to Closing, as may be reasonably requested
by the other party to consummate more effectively the purposes or subject matter
of this Agreement. Without limiting the generality of the foregoing, Purchaser
shall, if requested by Seller, execute acknowledgments of receipt with respect
to any materials delivered by Seller to Purchaser with respect to the Property.
The provisions of this Section 10.12 shall survive Closing.

X.13 Counterparts; Faxed Signatures. This Agreement may be executed in
counterparts, and all such executed counterparts shall constitute the same
agreement. It shall be necessary to account for only one such counterpart in
proving this Agreement. Faxed signatures shall have the same binding effect as
original signatures.

X.14 Severability. If any provision of this Agreement is determined by a court
of competent jurisdiction to be invalid or unenforceable, the remainder of this
Agreement shall nonetheless remain in full force and effect.

X.15 Applicable Law. THIS AGREEMENT IS PERFORMABLE IN THE DISTRICT OF COLUMBIA
AND SHALL IN ALL RESPECTS BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE
SUBSTANTIVE FEDERAL LAWS OF THE UNITED STATES AND THE LAWS OF THE DISTRICT OF
COLUMBIA. SELLER AND PURCHASER HEREBY IRREVOCABLY SUBMIT TO THE JURISDICTION OF
ANY COURT OF GENERAL JURISDICTION SITTING IN THE DISTRICT OF COLUMBIA IN ANY
ACTION OR PROCEEDING ARISING OUT OF OR RELATING TO THIS AGREEMENT AND HEREBY
IRREVOCABLY AGREE THAT ALL CLAIMS IN RESPECT OF SUCH ACTION OR PROCEEDING SHALL
BE HEARD AND DETERMINED IN A COURT OF GENERAL JURISDICTION IN THE DISTRICT OF
COLUMBIA. PURCHASER AND SELLER AGREE THAT THE PROVISIONS OF THIS SECTION 10.15
SHALL SURVIVE THE CLOSING OF THE TRANSACTION CONTEMPLATED HEREUNDER OR THE EARLY
TERMINATION OF THIS AGREEMENT.

X.16 No Third Party Beneficiary. The provisions of this Agreement and of the
documents to be executed and delivered at Closing are and will be for the
benefit of Seller and Purchaser only and are not for the benefit of any third
party, and accordingly, no third party shall have the right


                                       39
<PAGE>

to enforce the provisions of this Agreement or of the documents to be executed
and delivered at Closing.

X.17 Exhibits and Schedules. The following schedules or exhibits attached hereto
shall be deemed to be an integral part of this Agreement:

      (1) Exhibit A - Legal Description of the Land

      (2) Exhibit B - Personal Property

      (3) Exhibit C - Lease Schedule

      (4) Exhibit D - Operating Agreements Schedule

      (5) Exhibit E - Tenant Estoppel Form

      (6) Exhibit F - Form of Assignment and Assumption Agreement

      (7) Exhibit G - Leasing Commission Schedule

      (8) Schedule 4.4(b)(8) - Schedule of Delinquent Rents

      (9) Schedule 5.1(q) - Schedule of Security Deposits

      (10) Schedule 5.1(s) - Rent Roll

X.18 Captions. The section headings appearing in this Agreement are for
convenience of reference only and are not intended, to any extent and for any
purpose, to limit or define the text of any section or any subsection hereof.

X.19 Construction. The parties acknowledge that the parties and their counsel
have reviewed and revised this Agreement and that the normal rule of
construction to the effect that any ambiguities are to be resolved against the
drafting party shall not be employed in the interpretation of this Agreement or
any exhibits or amendments hereto.

X.20 Termination of Agreement. It is understood and agreed that if either
Purchaser or Seller terminates this Agreement pursuant to a right of termination
granted hereunder, such termination shall operate to relieve Seller and
Purchaser from all obligations under this Agreement, except for such obligations
as are specifically stated herein to survive the termination of this Agreement.

X.21 Survival. The provisions of the following Sections of this Agreement shall
survive Closing and shall not be merged into the execution and delivery of the
Deed: 3.1; 4.2(j); 4.4; 4.5; 4.6(f); 5.1; 5.3; 5.6; 5.7; 8.1; 9.1; 9.2; 10.1;
10.2; 10.5; 10.8; 10.12; 10.15; and 10.22. The foregoing is in addition to and
not in exclusion of any survival provisions that may elsewhere be set forth in
this Agreement.


                                       40
<PAGE>

X.22 Separate Account. Notwithstanding anything to the contrary in this
Agreement or in any document delivered by Seller in connection with the
consummation of the transaction contemplated hereby, it is expressly understood
and agreed that The Equitable Life Assurance Society of the United States is
acting solely on the behalf, and for the benefit, of Separate Account 16-III and
Seller's liability shall be, and is, limited to, and payable and collectible
only out of, assets allocated to, or held by Seller for the benefit of, Separate
Account 16-III (including, without limitation, the subject property) and no
other property or asset of Seller or of any of Seller's directors, officers,
employees, agents, shareholders, contractholders or policyholders, shall be
subject to any lien, levy, execution, setoff, or other enforcement procedure for
satisfaction of any right or remedy of Purchaser in connection with the
transaction contemplated hereby.

X.23 Soil Disclosure. Pursuant to Section 45-508(b) of the District of Columbia
Code, Purchaser is hereby advised by Seller that the characteristic of the soil
of the Property as described by the Soil Conservation Service of the United
States Department of Agriculture in the Soil Survey of the District of Columbia
published in 1976, as the same may be amended from time to time, and as shown on
the Soil Maps of the District of Columbia at the back of that publication, is
Urban Land-Not Rated. For further information, Purchaser can contact a soil
testing laboratory, the District of Columbia Department of Environmental
Services, or the Soil Conservation Service of the United States Department of
Agriculture. The foregoing is given pursuant to District of Columbia statutory
requirements and does not constitute either (i) a representation of warranty by
Seller as to soil characteristic or condition, or (ii) a limitation on
Purchaser's right to inspect and study the soil characteristic and condition
pursuant to Section 3.1 of this Agreement.

X.24 UST Disclosure. In accordance with the requirements of the District of
Columbia Underground Storage Tank Management Act of 1990, as amended by the
District of Columbia Underground Storage Tank Management Act of 1990 Amendment
Act of 1992 (D.C. Code Section 6-995.1 et seq.) (the "UST Act") and the D.C.
Underground Storage Tank Regulations, 20 DCMR Chapters 55-68 (the
"Regulations"), Seller has knowledge, and has informed Purchaser, that during
Seller's ownership of the Property (except as disclosed in the Phase I Report),
no underground storage tanks were removed from the Property, and no underground
storage tanks currently exist on the Property. The foregoing is given pursuant
to District of Columbia statutory and regulatory requirements and does not
constitute either (i) a representation of warranty by Seller as to the presence
or removal of underground storage tanks, or (ii) a limitation on Purchaser's
right to inspect and study the environmental condition of the Property pursuant
to Section 3.1 of this Agreement. Information pertaining to underground storage
tanks and underground storage tank removals of which the District of Columbia
Government has received notification may be on file with the Department of
Consumer and Regulatory Affairs, Environmental Regulation Administration,
Underground Storage Tank Branch, 2100 Martin Luther King, Jr., Avenue, S.E.,
Washington, DC (Telephone: 202/404-1167).

X.25 Underground Facilities Compliance. In accordance with the District of
Columbia


                                       41
<PAGE>

Underground Facilities Protection Act, as amended (D.C. Code Sections 43-1701 et
seq.) (the "Underground Facilities Act"), Purchaser shall be solely responsible
for providing any notifications required therein prior to performing any
excavation on the Property pursuant to Section 3.1 above, and any work performed
by or on behalf of Purchaser at the Property pursuant to Section 3.1 shall be
strictly in accordance with the Underground Facilities Act. Purchaser hereby
indemnifies Seller against and holds Seller harmless from any and all liability,
cost, damage or expense (including attorneys fees) suffered or incurred by
Seller on account of a violation by Purchaser of the foregoing requirements.

      IN WITNESS WHEREOF, the parties hereto have duly executed this Agreement
as of the Effective Date.

                          SELLER:


                          THE EQUITABLE LIFE ASSURANCE
                          SOCIETY OF THE UNITED STATES,a New
                          York corporation (solely on behalf of and for
                          the benefit of its Separate Account 16-III, known as
                          the "Value Enhancement Fund")

                          By:
                             ---------------------------------------------------
                                Michael J. Daly, Jr.
                                Investment Officer

                          PURCHASER:


                          MACK-CALI REALTY ACQUISITION CORP.,
                          a Delaware corporation

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

The undersigned agrees to serve as the Escrow Agent and to be bound by the
provisions of Section 1.6 of this Agreement.

                          ESCROW AGENT:


                                       42
<PAGE>

                          COMMONWEALTH LAND TITLE INSURANCE COMPANY

                          By:
                             ---------------------------------------------------
                                Stuart S. Levin
                                Vice President


                                       43
<PAGE>

                                    Exhibit A
                          LEGAL DESCRIPTION OF THE LAND

All that certain lot or parcel or land situated, lying and being in the City of
Washington, District of Columbia and being more particularly described as
follows:

Part of Lots Eleven (11) and Twelve (12) in A. Jardin and George H. Williams'
subdivision of Square One Hundred Fifty-nine (159), as per plat recorded in
Liber W.B.M. at folio 21 in the Office of the Surveyor for the District of
Columbia; also Lots Forty-nine (49) and Fifty (50) in Mariana V. Lothrop's
subdivision of lots in Square 159, as per plat recorded in Liber 12 at folio 173
of said Surveyor's Office Records, all of said parcel being more particularly
described as follows:

Beginning at the Southwesterly corner of Lot 12, being the intersection of the
Northerly line of Rhode Island Avene with the Easterly line of Connecticut
Avenue, thence Northwesterly with the line of Connecticut Avenue, a distance of
87.22 feet; thence Easterly and parallel with the line of Rhode Island Avenue, a
distance of 80.80 feet to the Westerly line of Lot 50; thence Northerly with
said Westerly line of Lot 50 a measured distance of 22.03 feet to the Northwest
corner of said Lot; thence Easterly with the Northerly lines of Lots 50 and 49,
being also partly along the Southerly line of an alley (closed), a distance of
100.00 feet to the Westerly line of an 18-foot public alley; thence
Southeasterly along the Westerly line of said alley, a distance of 109.21 feet
to the Northerly line of Rhode Island Avenue, being also the Southeasterly
corner of Lot 49; thence Westerly along the Northerly line of Rhode Island
Avenue, a distance of 180.00 feet to the Southwesterly corner of Lot 12 and the
place of beginning.

Note: At the date hereof said land is now known for assessment and taxation
purposes as Lot 855 in Square 159.


                                       44
<PAGE>

                                    Exhibit B
                                PERSONAL PROPERTY

1 set combination wrenches                2 telephones
1 short cut hack saw                      4 nextel radios
1 hack saw                                1 wet vac
1 framing square                          1 mighty mite vac
1 roto split                              2 pip wrenches
1 set assorted wrenches                   2 pair acid protectant rubber gloves
1 2 foot level                            1 push cart
1 torpedo level                           1 3-foot ladder
3 pair safety glasses                     1 6-foot ladder
1 set assorted hand tools                 1 8-foot ladder
1 hammer drill                            1 10-foot ladder
1 skill saw                               1 12-foot ladder
1 battery drill                           Extension cords
1 refrigeration evacuation machine        1 tank compressed nitrogen
1 portable air compressor                 1 hand truck
1 snow blower
1 set screw drivers
1 bench grinder
1 bench vice
1 fish tape
1 file pack
1 nut driver pack
3 sets ear protection
1 key cut machine
1 re-key kit
1 tap & die set
1 volt & amp meter
1 3/8 drive socket set
1 1/4 drive socket set
1 offset pipe wrench
1 office desk
4 chairs
1 refrigerator hole saw kit
1 refrigerator gauges
1 caulk gun
1 refrigerator
1 microwave
1 fax machine
1 salt spreader


                                       45
<PAGE>

                                    Exhibit C
                                 LEASE SCHEDULE

I.    Association of American Law Schools

      1.    Office Lease Agreement by and between Baput-DC Limited Partnership
            and Association of American Law Schools, dated November 28, 1989.

      2.    First Amendment to Office Lease Agreement, dated September 16, 1991.

      3.    Second Amendment to Office Lease Agreement, dated December 10, 1991.

      4.    Third Amendment to Office Lease Agreement by and between The
            Equitable Life Assurance Society of the United States and
            Association of American Law Schools, dated June 3, 1998.

II.   Belay & Belay Investment, Inc.

      1.    Retail Lease Agreement by and between Baput-DC Limited Partnership
            and Marketing Consulting Services, Inc., dated December ____, 1987.

      2.    Assignment of Lease by and between Marketing Consulting Services,
            Inc. and Belay & Belay Investment, Inc., dated September 27, 1989.

      3.    First Amendment to Retail Lease Agreement, dated November 25, 1992.

      4.    Second Amendment to Retail Lease Agreement, dated December 21, 1998.

III.  Brooks Brothers, Inc.

      1.    Retail Lease Agreement by and between The Equitable Life Assurance
            Society of the United States and Brooks Brothers, Inc., dated
            January 22, 1998.

IV.   Joseph M. Del Balzo

      1.    Office Lease Agreement by and between The Equitable Life Assurance
            Society of the United States and Joseph M. Del Balzo, dated March 9,
            1999.

      2.    Temporary Occupancy Agreement by and between The Equitable Life
            Assurance Society of the United States and Joseph M. Del Balzo,
            dated March 9, 1999.

V.    Leo A. Daly Company

      1.    Office Lease Agreement by and between Baput-DC Limited Partnership
            and Leo A. Daly Company, dated November 15, 1985.

      2.    First Amendment to Office Lease Agreement, dated April 30, 1987.

      3.    Second Amendment to Office Lease Agreement, dated May 23, 1988.


                                       46
<PAGE>

      4.    Third Amendment to Office Lease Agreement, dated December 19, 1990.

      5.    Fourth Amendment to Office Lease Agreement, dated March 13, 1992.

      6.    Fifth Amendment to Office Lease Agreement by and between The
            Equitable Life Assurance Society of the United States and Leo A.
            Daly Company, dated October 24, 1997.

VII.  Pathfinder International

      1.    Office Lease Agreement by and between The Equitable Life Assurance
            Society of the United States and Pathfinder International, dated
            January 11, 1996.

VIII. Police Foundation

      1.    Office Lease Agreement by and between The Equitable Life Assurance
            Society of the United States and Police Foundation, dated March 31,
            1997.

VIIII. RFE/RL, Inc.

      1.    Office Lease Agreement by and between Baput-DC Limited Partnership
            and RFE/RL, Inc., dated August 19, 1985.

      2.    First Amendment to Office Lease Agreement, dated July 15, 1988.

      3.    Second Amendment to Office Lease Agreement, dated March 14, 1989.

      4.    Third Amendment to Office Lease Agreement, dated December 28, 1989.

      5.    Fourth Amendment to Office Lease Agreement by and between Rds 1201
            Connecticut Associates, L.P. and RFE/RL, Inc., dated April 30, 1992.

      6.    Fifth Amendment to Office Lease Agreement, dated October 15, 1993.

      7.    Sixth Amendment to Office Lease Agreement by and between The
            Equitable Life Assurance Society of the United States and RFE/RL,
            Inc., dated January 23, 1995.

      8.    Seventh Amendment to Office Lease Agreement, dated May 27, 1998.

      9.    Temporary Occupancy Agreement.

IX.   Zuckerman, Spaeder, Goldstein, Taylor & Kolker

      1.    Office Lease Agreement by and between Rds 1201 Connecticut
            Associates, L.P. and Zuckerman, Spaeder, Goldstein, Taylor & Kolker,
            dated October 4, 1993.

      2.    First Amendment to Office Lease Agreement by and between The
            Equitable Life Assurance Society of the United States and Zuckerman,
            Spaeder, Goldstein, Taylor & Kolker, dated April 29, 1994.

      3.    Second Amendment to Office Lease Agreement, dated August 30, 1994.

      4.    Third Amendment to Office Lease Agreement by and between The
            Equitable Life


                                       47
<PAGE>

            Assurance Society of the United States and Zuckerman, Spaeder,
            Goldstein, Taylor & Kolker, L.L.P., dated June 3, 1998.

X.    Federal Express

      1.    Placement Agreement by and between The Equitable Life Assurance
            Society of the United States and Federal Express Corporation,
            commencing on May 1, 1996.


                                       48
<PAGE>

                                    Exhibit D
                          OPERATING AGREEMENTS SCHEDULE

1.    Cleaning services contract with Total Quality Service.

2.    Concierge services contract with Classic Concierge.

3.    Interior landscaping contract with Rolling Greens.

4.    Uniform contract with Cintas.

5.    Elevator maintenance agreement with Otis Elevator Company.

6.    Metal refinishing contract with Cameo Bronze.

7.    Water treatment contract with ECOLAB, Inc.

8.    Trash removal contract with Waste Management, Inc.

9.    Pest control contract with Owl Pest Control.

10.   Access Control contract with Kastle Systems, Inc.

11.   Marble refinishing contract with Total Quality Service.

12.   Lobby Floral Arrangements contract with Rolling Greens.

13.   Leasing Management Agreement by and between The Equitable Life Assurance
      Society of the United States and Trammell Crow Real Estate Services, Inc.,
      dated March 27, 1996 (To be terminated at Seller's expense prior to
      Closing).

14.   Construction Management Agreement by and between The Equitable Life
      Assurance Society of the United States and Technical Property Services,
      Inc., dated December 1, 1995 (only to the extent that the work to be
      performed is pursuant to the Del Balzo lease).

15.   Work Agreement by and between The Equitable Life Assurance Society of the
      United States and STAT Construction, Inc. (only to the extent that the
      work to be performed is pursuant to the Del Balzo lease).


                                       49
<PAGE>

                                    Exhibit E
                           TENANT ESTOPPEL CERTIFICATE

                                     [Date]

Mack-Cali Realty Acquisition Corp.
c/o Mack-Cali Realty Corporation
11 Commerce Drive
Cranford, NJ 07016

            Property:   1201 Connecticut Avenue,
                        N.W Washington, D.C. 20036

      The undersigned, as Tenant under that certain lease dated ________________
 (the "Lease"), made with __________________ ("Landlord") does hereby certify to
Mack-Cali Realty Acquisition Corp. and its successors and assigns (collectively,
"Purchaser") and to any lender or mortgagee of Purchaser with respect to
Purchaser's acquisition of the Property of which the Demised Premises (as
hereinafter defined) form a part:

1.    That the premises leased by Tenant (the "Demised Premises") at the
      Property pursuant to the Lease are described as:

                  ___________ square feet on the _____ floor

2.    That the Lease is now in full force and effect and has not has not been
      modified, changed, altered or amended in any respect, except as set forth
      below, and is the only Lease or agreement between the undersigned and
      Landlord affecting the Demised Premises (if none, state "none"). A true
      and complete copy of the Lease, together with any and all modifications,
      amendments and/or assignments thereto, are annexed hereto as Exhibit A.
      There are no subleases for the Demised Premises;

3.    That the Demised Premises have been completed in accordance with the terms
      of the Lease; that Tenant has accepted possession of the Demised Premises;
      and that Tenant now occupies the same and is open for business. All
      improvements, alterations or additions to be constructed in the Demised
      Premises by Landlord pursuant to the Lease have been completed and
      accepted by Tenant and any other items of an executory nature have been
      completed in accordance with the terms of the Lease. All contributions
      required from Landlord for improvements to the Demised Premises have been
      paid in full to Tenant;


                                       50
<PAGE>

4.    That the original Lease term began on ______________, 19______ and will
      expire on _____________________; that Tenant pays rent on a current basis
      and rent has been paid through ________________; that no rent has been
      paid by Tenant for more than one month in advance; that the rent payable
      under the Lease is the amount of fixed rent provided thereunder, which is
      annual fixed rent payable to Landlord of $_______________; that as of the
      date hereof, additional rent of $_______________ is payable to Landlord on
      account of utility costs, real estate taxes and operating expenses; that
      the base amount for such additional rent is $_____________ (or the base
      year is __________); that there is no claim or basis for an adjustment
      thereto; and that the amounts of fixed and additional rent are being paid
      on a current basis;

5.    That Tenant has paid to Landlord a security deposit of $______________,
      and Tenant has no knowledge of any claim made by Landlord against the
      security deposit;

6.    That Tenant has not given Landlord any notice of any claim arising under
      the Lease nor any notice of a default on the part of Landlord under the
      Lease which has not been cured. There are no defaults by Landlord under
      the Lease as of the date hereof. As of the date hereof, the undersigned is
      entitled to no credit, no free rent and no offset, counterclaim or
      deduction in rent;

7.    That Tenant has _______ option(s) to renew the Lease for a period of
      _______ years upon the terms set forth in the Lease, and that none of such
      options have been exercised except (if none, state "none") _____________;

8.    That Tenant has (i) no option to expand into additional space in the
      Property, (ii) no right of first refusal of any space in the Property; or
      (iii) no option to acquire all or any part of the Property;

9.    That the full name and current mailing address for Tenant, and the address
      for all notices to Tenant, are as follows:

10.   Except as set forth on Exhibit B, Tenant does not use, store, manufacture,
      generate, handle or dispose of at the Property, any chemical, element or
      compound which is identified or classified as a regulated substance, toxic
      substance, hazardous substance, hazardous waste, pollution, pollutant,
      toxic pollutant, contaminant, solid waste or special waste (collectively,
      "Hazardous Materials") under any law, ordinance, rule, regulation, order,
      directive or requirement of any governmental authority (collectively,
      "Laws"), other than small quantities of household cleaning and office
      supplies. To the extent Hazardous Materials are set forth on Exhibit B,
      each of such Hazardous Materials is used, stored, manufactured, generated,
      handled and disposed of in accordance with Laws; and

11.   That no actions, whether voluntary or otherwise, are pending against the
      undersigned


                                       51
<PAGE>

      under the bankruptcy laws of the United States or any State thereof.


Dated ____________, 1999            TENANT:

                                    ________________________________
                                    a ______________________________

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


                                       52
<PAGE>

                                    Exhibit F
                   FORM OF ASSIGNMENT AND ASSUMPTION AGREEMENT

      THIS ASSIGNMENT AND ASSUMPTION OF AGREEMENT (this "Assignment") is made as
of _________, 1999, by and between THE EQUITABLE LIFE ASSURANCE SOCIETY OF THE
UNITED STATES, a New York corporation (solely on behalf of and for the benefit
of its Separate Account 16-III, known as the "Value Enhancement Fund")
("Assignor"), and [__________________], a [_________________] ("Assignee").

                                    RECITALS

      A. Concurrently with the execution and delivery of this Assignment,
Assignor is conveying to Assignee, by Special Warranty Deed (the "Deed"), that
certain tract of land (collectively, the "Land") more specifically described in
Exhibit A attached hereto and made a part hereof for all purposes, together with
the improvements located thereon (the "Improvements"), and by Bill of Sale and
Assignment (the "Bill of Sale"), all of the personal property owned by Assignor
upon the Land or within or upon the Improvements (the "Personal Property").

      B. Assignor desires to assign, transfer and convey to Assignee, and
Assignee desires to accept and obtain, all of Assignor's right, title and
interest in and to the Assigned Properties (as hereinafter defined), subject to
the terms and conditions set forth herein.

      NOW, THEREFORE, for and in consideration of the sum of Ten and No/100
Dollars ($10.00) and other good and valuable consideration in hand paid by
Assignee to Assignor, and the mutual covenants set forth herein, the receipt and
sufficiency of which are hereby acknowledged, Assignor does hereby SELL, ASSIGN,
CONVEY, TRANSFER, SET OVER and DELIVER unto Assignee all of Assignor's right,
title and interest in and to the following (collectively, the "Assigned
Properties"):

      (a) the leases described in Exhibit B attached hereto and made a part
hereof (collectively, the "Leases"); and

      (b) the assignable contracts and agreements described in Exhibit C
attached hereto and made a part hereof (collectively, the "Operating
Agreements"), together with (i) all assignable existing warranties and
guaranties (expressed or implied) issued to Assignor in connection with the
Improvements or the Personal Property and (ii) all transferable consents,
authorizations, variances or waivers, licenses, permits and approvals, if any;
provided, however, that Assignor makes no representation or warranty with
respect to the assignability of or any other matter relating to any of the
foregoing, except as set forth in the Purchase Agreement (as defined below).


                                       53
<PAGE>

      TO HAVE AND TO HOLD the foregoing described Assigned Properties unto
Assignee, its successors and assigns, forever.

      This Assignment is made by Assignor and accepted by Assignee subject to
the provisions set forth in the Purchase and Sale Agreement, dated as of
[___________], 1999, between Assignor and Assignee (together with all amendments
and addenda thereto, if any, the "Purchase Agreement").

      By execution of this Assignment, Assignee assumes and agrees to perform
all of the covenants, agreements and obligations under the Assigned Properties
binding on Assignor or the Land, Improvements, or Personal Property (such
covenants, agreements and obligations being herein collectively referred to as
the "Contractual Obligations"), as such Contractual Obligations shall arise or
accrue from and after the date of this Assignment. Without limiting the
generality of the immediately preceding sentence, Assignee acknowledges the
receipt of the security deposits required by the Leases described in the
schedule of security deposits attached to Exhibit B. Assignee hereby agrees to
indemnify, hold harmless and defend Assignor from and against any and all
obligations, liabilities, costs and claims (including reasonable attorney's
fees) arising as a result of or with respect to any of the Contractual
Obligations that are attributable to the period of time from and after the date
of this Assignment.

      Assignor agrees to indemnify, hold harmless and defend Assignee from and
against any and all obligations, liabilities, costs and claims (including
reasonable attorney's fees) arising as a result of or with respect to any of the
Contractual Obligations that are attributable to the period of time prior to the
date of this Assignment.

      ASSIGNEE ACKNOWLEDGES THAT IT HAS INSPECTED THE ASSIGNED PROPERTIES AND
THAT THIS ASSIGNMENT IS MADE BY ASSIGNOR AND ACCEPTED BY ASSIGNEE WITHOUT
REPRESENTATION OR WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR STATUTORY, AND
WITHOUT RECOURSE AGAINST ASSIGNOR, EXCEPT AS EXPRESSLY SET FORTH HEREIN OR IN
THE PURCHASE AGREEMENT.

      This Assignment may be executed in counterparts, and all such executed
counterparts shall constitute the same agreement. It shall be necessary to
account for only one such counterpart in proving this Assignment.

      EXECUTED to be effective as of the date set forth above.

                           ASSIGNOR:


                           THE EQUITABLE LIFE ASSURANCE SOCIETY
                           OF THE UNITED STATES, a New York


                               54
<PAGE>

                           corporation, solely on behalf of and for the benefit
                           of its Separate Account 16-III, known as the "Value
                           Enhancement Fund"

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

                           ASSIGNEE:

                           [____________________________],
                           a [________________________]

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

List of Attachments:
Exhibit A - Property Description
Exhibit B - Lease Schedule
Exhibit C - Operating Agreements Schedule


                                       55
<PAGE>

                                    Exhibit G
                           LEASE BROKERAGE COMMISSIONS

1.    Leasing Management Agreement by and between The Equitable Life Assurance
      Society of the United States and Trammell Crow Real Estate Services, Inc.,
      dated March 27, 1996 (to be terminated at Seller's expense prior to
      Closing).

2.    Leasing Commission payable to Trammell Crow Real Estate Services, Inc.,
      and Fred Ezra pursuant to the Joseph M. Del Balzo Lease (payable by
      Seller).


                                       56
<PAGE>

                                    Exhibit H
                              5TH FLOOR SPACE PLAN

                                   (Attached)


                                       57
<PAGE>

                               Schedule 4.4(b)(8)
                          SCHEDULE OF DELINQUENT RENTS

                                   (Attached)


                                       58
<PAGE>

                                 Schedule 5.1(q)
                          SCHEDULE OF SECURITY DEPOSITS

                                   (Attached)


                                       59
<PAGE>

                                 Schedule 5.1(s)
                                    RENT ROLL

                                   (Attached)


                                       60