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                                                                   EXHIBIT 10.20

                             BOSTON PROPERTIES, INC.

                            EXECUTIVE SEVERANCE PLAN


     1.   PURPOSE. Boston Properties, Inc. (the "Company") considers it
essential to the best interests of its stockholders to foster the continuous
employment of key management personnel. The Board of Directors of the Company
(the "Board") recognizes, however, that, as is the case with many publicly held
corporations, the possibility of a Change in Control (as defined in Section 2
hereof) exists and that such possibility, and the uncertainty and questions
which it may raise among management, may result in the departure or distraction
of management personnel to the detriment of the Company and its stockholders.
Therefore, the Board has determined that the Boston Properties, Inc. Executive
Severance Plan (the "Plan") should be adopted to reinforce and encourage the
continued attention and dedication of the Senior Vice-Presidents of the Company
and the Vice Presidents with ten (10) or more years of service with the Company
(each, a "Covered Employee"; collectively, the "Covered Employees"), to their
assigned duties without distraction in the face of potentially disturbing
circumstances arising from the possibility of a Change in Control. Nothing in
this Plan shall be construed as creating an express or implied contract of
employment and, except as otherwise agreed in writing between the Covered
Employee and the Company or any of its subsidiaries or affiliates (together with
the Company, the "Employers"), the Covered Employee shall not have any right to
be retained in the employ of the Employers.

     2.   CHANGE IN CONTROL. For purposes of this Plan, a "Change in Control"
shall mean the occurrence of any one of the following events:

          (a)  any "PERSON," as such term is used in Sections 13(d) and 14(d) of
     the Act (other than any of the Employers, Mortimer B. Zuckerman, Edward H.
     Linde, any "AFFILIATE" or "ASSOCIATE" (as such terms are defined in Rule
     12b-2 under the Act) of Mortimer B. Zuckerman or Edward H. Linde, or any
     trustee, fiduciary or other person or entity holding securities under any
     employee benefit plan or trust of any of the Employers), together with all
     "AFFILIATES" and "ASSOCIATES" (as such terms are defined in Rule 12b-2
     under the Act) of such person, shall become the "BENEFICIAL OWNER" (as such
     term is defined in Rule 13d-3 under the Act), directly or indirectly, of
     securities of the Company representing 25 percent or more of the combined
     voting power of the Company's then outstanding securities having the right
     to vote in an election of the Company's Board of Directors ("Voting
     Securities") (other than as a result of an acquisition of securities
     directly from the Company); provided that for purposes of determining the
     "BENEFICIAL OWNERSHIP" (as such term is defined in Rule 13d-3 under the
     Act) of any "GROUP" of which Mortimer B. Zuckerman, Edward H. Linde or any
     of their affiliates or associates is a member (each such entity or
     individual, a "Related Party"), there shall not be attributed to the
     "BENEFICIAL OWNERSHIP" (as such term is defined in Rule 13d-3 under the
     Act) of such group any shares beneficially owned by any Related Party; or

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          (b)  persons who, as of the effective date of the Company's initial
     public offering of Stock, constitute the Company's Board of Directors (the
     "Incumbent Directors") cease for any reason, including, without limitation,
     as a result of a tender offer, proxy contest, merger or similar
     transaction, to constitute at least a majority of the Board, provided that
     any person becoming a director of the Company subsequent to such date shall
     be considered an Incumbent Director if such person's election was approved
     by or such person was nominated for election by either (A) a vote of at
     least two-thirds of the Incumbent Directors or (B) a vote of at least a
     majority of the Incumbent Directors who are members of a nominating
     committee comprised, in the majority, of Incumbent Directors; or

          (c)  the stockholders of the Company shall approve (A) any
     consolidation or merger of the Company where the stockholders of the
     Company, immediately prior to the consolidation or merger, would not,
     immediately after the consolidation or merger, "BENEFICIALLY OWN" (as such
     term is defined in Rule 13d-3 under the Act), directly or indirectly,
     shares representing in the aggregate 60 percent or more of the voting
     shares of the corporation issuing cash or securities in the consolidation
     or merger (or of its ultimate parent corporation, if any), (B) any sale,
     lease, exchange or other transfer to an unrelated party (in one transaction
     or a series of transactions contemplated or arranged by any party as a
     single plan) of all or substantially all of the assets of the Company or
     (C) any plan or proposal for the liquidation or dissolution of the Company.

     Notwithstanding the foregoing, a "Change of Control" shall not be deemed to
have occurred for purposes of the foregoing clause (a) solely as the result of
an acquisition of securities by the Company which, by reducing the number of
shares of Voting Securities outstanding, increases the proportionate number of
shares of Voting Securities beneficially owned by any person (as defined in the
foregoing clause (a)) to 25 percent or more of the combined voting power of all
then outstanding Voting Securities; PROVIDED, HOWEVER, that if such person shall
thereafter become the beneficial owner of any additional shares of Voting
Securities (other than pursuant to a stock split, stock dividend, or similar
transaction or as a result of an acquisition of securities directly from the
Company), then a "CHANGE OF CONTROL" shall be deemed to have occurred for
purposes of the foregoing clause (a).

     3.   TERMINATING EVENT. A "Terminating Event" shall mean the termination of
employment of a Covered Employee in connection with any of the events provided
in this Section 3 occurring within twelve (12) months following a Change in
Control:

          (a)  termination by the Employers of the employment of the Covered
     Employee with the Employers for any reason other than for Cause or the
     death or disability (as determined under the Employers' then existing
     long-term disability coverage) of such Covered Employee. "Cause" shall
     mean, and shall be limited to, the occurrence of any one or more of the
     following events:

               (i)   a willful act of dishonesty by the Covered Employee with
          respect to any matter involving any of the Employers; or

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               (ii)  conviction of the Covered Employee of a crime involving
          moral turpitude; or

               (iii) the deliberate or willful failure by the Covered Employee
          (other than by reason of the Covered Employee's physical or mental
          illness, incapacity or disability) to substantially perform the
          Covered Employee's duties with the Employers and the continuation of
          such failure for a period of 30 days after delivery by the Employers
          to the Covered Employee of written notice specifying the scope and
          nature of such failure and their intention to terminate the Covered
          Employee for Cause.

          A Terminating Event shall not be deemed to have occurred pursuant to
     this Section 3(a) solely as a result of the Covered Employee being an
     employee of any direct or indirect successor to the business or assets of
     either of the Employers, rather than continuing as an employee of the
     Employers following a Change in Control. For purposes of clauses (i) and
     (iii) of this Section 3(a), no act, or failure to act, on the Covered
     Employee's part shall be deemed "willful" unless done, or omitted to be
     done, by the Covered Employee without reasonable belief that the Covered
     Employee's act, or failure to act, was in the best interest of the
     Employers; or

          (b)  termination by the Covered Employee of the Covered Employee's
     employment with the Employers for Good Reason. "Good Reason" shall mean the
     occurrence of any of the following events:

               (i)   a substantial adverse change in the nature or scope of the
          Covered Employee's responsibilities, authorities, title, powers,
          functions, or duties from the responsibilities, authorities, powers,
          functions, or duties exercised by the Covered Employee immediately
          prior to the Change in Control; or

               (ii)  a reduction in the Covered Employee's annual base salary as
          in effect on the date hereof or as the same may be increased from time
          to time except for across-the-board salary reductions similarly
          affecting all or substantially all management employees; or

               (iii) the relocation of the Employers' offices at which the
          Covered Employee is principally employed immediately prior to the date
          of a Change in Control to a location more than thirty (30) miles from
          such offices, or the requirement by the Employers for the Covered
          Employee to be based anywhere other than the Employers' offices at
          such location, except for required travel on the Employers' business
          to an extent substantially consistent with the Covered Employee's
          business travel obligations immediately prior to the Change in
          Control; or

               (iv)  the failure by the Employers to pay to the Covered Employee
          any portion of his compensation or to pay to the Covered Employee any
          portion of an

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          installment of deferred compensation under any deferred compensation
          program of the Employers within fifteen (15) days of the date such
          compensation is due without prior written consent of the Covered
          Employee; or

               (v)   the failure by the Employers to obtain an effective
          agreement from any successor to assume and agree to perform this
          Agreement.

     4.   SPECIAL TERMINATION BENEFITS. In the event a Terminating Event occurs
within twelve (12) months after a Change in Control with respect to a Covered
Employee,

          (a)  the Employers shall pay to the Covered Employee an amount equal
     to the sum of the following:

               (i)   two (2) times the amount of the current annual base salary
          of the Covered Employee, determined prior to any reductions for
          pre-tax contributions to a cash or deferred arrangement or a cafeteria
          plan; and

               (ii)  two (2) times the amount of the average annual bonus earned
          by the Covered Employee with respect to the three (3) calendar years
          immediately prior to the Change in Control.

     Said amount shall be paid in one lump sum payment no later than thirty-one
     (31) days following the Date of Termination (as such term is defined in
     Section 7(b)); and

          (b)  the Employers shall continue to provide health, dental and life
     insurance to the Covered Employee, on the same terms and conditions as
     though the Covered Employee had remained an active employee, for
     twenty-four (24) months after the Terminating Event; and

          (c)  the Employers shall provide COBRA benefits to the Covered
     Employee following the end of the period referred to in Section 4(b) above,
     such benefits to be determined as though the Covered Employee's employment
     had terminated at the end of such period; and

          (d)  the Employers shall pay to the Covered Employee all reasonable
     legal and mediation fees and expenses incurred by the Covered Employee in
     obtaining or enforcing any right or benefit provided by this Plan, except
     in cases involving frivolous or bad faith litigation initiated by the
     Covered Employee; and

          (e)  the Employers shall provide to the Covered Employee financial
     counseling, tax preparation assistance and outplacement counseling for
     twenty-four (24) months after the Terminating Event.

     Notwithstanding the foregoing, the special termination benefits required by
Section 4(a) shall be offset by any amount paid or payable to the Covered
Employee by the Employers under the terms of any employment agreement or other
plan.

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     5.  ADDITIONAL BENEFITS.

          (a)  Anything in this Plan to the contrary notwithstanding, in the
     event it shall be determined that any compensation payment or distribution
     by the Employers to or for the benefit of the Covered Employee, whether
     paid or payable or distributed or distributable pursuant to the terms of
     this Plan or otherwise (the "Severance Payments"), would be subject to the
     excise tax imposed by Section 4999 of the Internal Revenue Code of 1986, as
     amended (the "Code"), or any interest or penalties are incurred by the
     Covered Employee with respect to such excise tax (such excise tax, together
     with any such interest and penalties, are hereinafter collectively referred
     to as the "Excise Tax"), then the Covered Employee shall be entitled to
     receive an additional payment (a "Gross-Up Payment") such that the net
     amount retained by the Covered Employee, after deduction of any Excise Tax
     on the Severance Payments, any Federal, state, and local income tax,
     employment tax and Excise Tax upon the payment provided by this subsection,
     and any interest and/or penalties assessed with respect to such Excise Tax
     and not after the deduction of any other taxes or amounts, shall be equal
     to the Severance Payments. (The Gross-Up Payment is not intended to
     compensate the Covered Employee for any income taxes payable with respect
     to the Severance Payments.)

          (b)  Subject to the provisions of Section 5(c), all determinations
     required to be made under this Section 5, including whether a Gross-Up
     Payment is required and the amount of such Gross-Up Payment, shall be made
     by Coopers & Lybrand, L.L.P. or any other nationally recognized accounting
     firm selected by the Employers (the "Accounting Firm"), which shall provide
     detailed supporting calculations both to the Employers and the Covered
     Employee within 15 business days of the Date of Termination, if applicable,
     or at such earlier time as is reasonably requested by the Employers or the
     Covered Employee. For purposes of determining the amount of the Gross-Up
     Payment, the Covered Employee shall be deemed to pay federal income taxes
     at the highest marginal rate of federal income taxation applicable to
     individuals for the calendar year in which the Gross-Up Payment is to be
     made, and state and local income taxes at the highest marginal rates of
     individual taxation in the state and locality of the Covered Employee's
     residence on the Date of Termination, net of the maximum reduction in
     federal income taxes which could be obtained from deduction of such state
     and local taxes. The initial Gross-Up Payment, if any, as determined
     pursuant to this Section 5(b), shall be paid to the Covered Employee within
     five days of the receipt of the Accounting Firm's determination. If the
     Accounting Firm determines that no Excise Tax is payable by the Covered
     Employee, the Employers shall furnish the Covered Employee with an opinion
     of counsel that failure to report the Excise Tax on the Covered Employee's
     applicable federal income tax return would not result in the imposition of
     a negligence or similar penalty. Any determination by the Accounting Firm
     shall be binding upon the Employers and the Covered Employee. As a result
     of the uncertainty in the application of Section 4999 of the Code at the
     time of the initial determination by the Accounting Firm hereunder, it is
     possible that Gross-Up Payments which will not have been made by the
     Employers should have been made (an "Underpayment"). In the event that the
     Employers exhaust their remedies pursuant to Section 5(c) and the Covered
     Employee thereafter is required to make a payment of any Excise Tax, the
     Accounting Firm shall

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     determine the amount of the Underpayment that has occurred, consistent with
     the calculations required to be made hereunder, and any such Underpayment,
     and any interest and penalties imposed on the Underpayment and required to
     be paid by the Covered Employee in connection with the proceedings
     described in Section 5(c), shall be promptly paid by the Employers to or
     for the benefit of the Covered Employee.

          (c)  The Covered Employee shall notify the Employers in writing of any
     claim by the Internal Revenue Service that, if successful, would require
     the payment by the Employers of the Gross-Up Payment. Such notification
     shall be given as soon as practicable but no later than 10 business days
     after the Covered Employee knows of such claim and shall apprise the
     Employers of the nature of such claim and the date on which such claim is
     requested to be paid. The Covered Employee shall not pay such claim prior
     to the expiration of the 30-day period following the date on which he gives
     such notice to the Employers (or such shorter period ending on the date
     that any payment of taxes with respect to such claim is due). If the
     Employers notify the Covered Employee in writing prior to the expiration of
     such period that they desire to contest such claim, provided that the
     Employers have set aside adequate reserves to cover the Underpayment and
     any interest and penalties thereon that may accrue, the Covered Employee
     shall:

               (i)   give the Employers any information reasonably requested by
          the Employers relating to such claim,

               (ii)  take such action in connection with contesting such claim
          as the Employers shall reasonably request in writing from time to
          time, including, without limitation, accepting legal representation
          with respect to such claim by an attorney selected by the Employers,

               (iii) cooperate with the Employers in good faith in order
          effectively to contest such claim, and

               (iv)  permit the Employers to participate in any proceedings
          relating to such claim; provided, however, that the Employers shall
          bear and pay directly all costs and expenses (including additional
          interest and penalties) incurred in connection with such contest and
          shall indemnify and hold the Covered Employee harmless, on an
          after-tax basis, for any Excise Tax or income tax, including interest
          and penalties with respect thereto, imposed as a result of such
          representation and payment of costs and expenses. Without limitation
          on the foregoing provisions of this Section 5(c), the Employers shall
          control all proceedings taken in connection with such contest and, at
          their sole option, may pursue or forego any and all administrative
          appeals, proceedings, hearings and conferences with the taxing
          authority in respect of such claim and may, at their sole option,
          either direct the Covered Employee to pay the tax claimed and sue for
          a refund or contest the claim in any permissible manner, and the
          Covered Employee agrees to prosecute such contest to a determination
          before any administrative tribunal, in a court of initial jurisdiction
          and in one or more appellate courts, as the Employers shall determine;
          provided, however, that if the

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          Employers direct the Covered Employee to pay such claim and sue for a
          refund, the Employers shall advance the amount of such payment to the
          Covered Employee on an interest-free basis and shall indemnify and
          hold the Covered Employee harmless, on an after-tax basis, from any
          Excise Tax or income tax, including interest or penalties with respect
          thereto, imposed with respect to such advance or with respect to any
          imputed income with respect to such advance; and further provided that
          any extension of the statute of limitations relating to payment of
          taxes for the taxable year of the Covered Employee with respect to
          which such contested amount is claimed to be due is limited solely to
          such contested amount. Furthermore, the Employers' control of the
          contest shall be limited to issues with respect to which a Gross-Up
          Payment would be payable hereunder and the Covered Employee shall be
          entitled to settle or contest, as the case may be, any other issues
          raised by the Internal Revenue Service or any other taxing authority.

          (d)  If, after the receipt by the Covered Employee of an amount
     advanced by the Employers pursuant to Section 5(c), the Covered Employee
     becomes entitled to receive any refund with respect to such claim, the
     Covered Employee shall (subject to the Employers' complying with the
     requirements of Section 5(c)) promptly pay to the Employers the amount of
     such refund (together with any interest paid or credited thereon after
     taxes applicable thereto). If, after the receipt by the Covered Employee of
     an amount advanced by the Employers pursuant to Section 5(c), a
     determination is made that the Covered Employee shall not be entitled to
     any refund with respect to such claim and the Employers do not notify the
     Covered Employee in writing of their intent to contest such denial of
     refund prior to the expiration of 30 days after such determination, then
     such advance shall be forgiven and shall not be required to be repaid and
     the amount of such advance shall offset, to the extent thereof, the amount
     of Gross-Up Payment required to be paid.

     6.   WITHHOLDING. All payments made by the Employers under this Plan shall
be net of any tax or other amounts required to be withheld by the Employers
under applicable law.

     7.   NOTICE AND DATE OF TERMINATION; DISPUTES; ETC.

          (a)  NOTICE OF TERMINATION. Within twelve (12) months after a Change
     in Control, any purported termination of a Covered Employee's employment
     (other than by reason of death) shall be communicated by written Notice of
     Termination from the Employers to the Covered Employee or vice versa in
     accordance with this Section 7. For purposes of this Plan, a "Notice of
     Termination" shall mean a notice which shall indicate the specific
     termination provision in this Plan relied upon and the Date of Termination.
     Further, a Notice of Termination for Cause is required to include a copy of
     a resolution duly adopted by the affirmative vote of not less than
     two-thirds (2/3) of the entire membership of the Board at a meeting of the
     Board (after reasonable notice to the Covered Employee and an opportunity
     for the Covered Employee, accompanied by the Covered Employee's counsel, to
     be heard before the Board) finding that, in the good faith opinion of the
     Board, the termination met the criteria for Cause set forth in Section 3(a)
     hereof.

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          (b)  DATE OF TERMINATION. "Date of Termination," with respect to any
     purported termination of a Covered Employee's employment within twelve (12)
     months after a Change in Control, shall mean the date specified in the
     Notice of Termination. In the case of a termination by the Employers other
     than a termination for Cause (which may be effective immediately), the Date
     of Termination shall not be less than 30 days after the Notice of
     Termination is given. In the case of a termination by a Covered Employee,
     the Date of Termination shall not be less than 15 days from the date such
     Notice of Termination is given. Notwithstanding Section 3(a) of this Plan,
     in the event that a Covered Employee gives a Notice of Termination to the
     Employers, the Employers may unilaterally accelerate the Date of
     Termination and such acceleration shall not result in a second Terminating
     Event for purposes of Section 3(a) of this Plan.

          (c)  NO MITIGATION. The Covered Employee is not required to seek other
     employment or to attempt in any way to reduce any amounts payable to the
     Covered Employee by the Employers under this Plan. Further, the amount of
     any payment provided for in this Plan shall not be reduced by any
     compensation earned by the Covered Employee as the result of employment by
     another employer, by retirement benefits, by offset against any amount
     claimed to be owed by the Covered Employee to the Employers, or otherwise.

          (d)  MEDIATION OF DISPUTES. The parties shall endeavor in good faith
     to settle within 90 days any controversy or claim arising out of or
     relating to this Plan or the breach thereof through mediation with JAMS,
     Endispute or similar organizations. If the controversy or claim is not
     resolved within 90 days, the parties shall be free to pursue other legal
     remedies in law or equity.

     8.   BENEFITS AND BURDENS. This Plan shall inure to the benefit of and be
binding upon the Employers and the Covered Employees, their respective
successors, executors, administrators, heirs and permitted assigns. In the event
of a Covered Employee's death after a Terminating Event but prior to the
completion by the Employers of all payments due him under this Plan, the
Employers shall continue such payments to the Covered Employee's beneficiary
designated in writing to the Employers prior to his death (or to his estate, if
the Covered Employee fails to make such designation).

     9.   ENFORCEABILITY. If any portion or provision of this Plan shall to any
extent be declared illegal or unenforceable by a court of competent
jurisdiction, then the remainder of this Plan, or the application of such
portion or provision in circumstances other than those as to which it is so
declared illegal or unenforceable, shall not be affected thereby, and each
portion and provision of this Plan shall be valid and enforceable to the fullest
extent permitted by law.

     10.  WAIVER. No waiver of any provision hereof shall be effective unless
made in writing and signed by the waiving party. The failure of any party to
require the performance of any term or obligation of this Plan, or the waiver by
any party of any breach of this Plan, shall not prevent any subsequent
enforcement of such term or obligation or be deemed a waiver of any subsequent
breach.

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     11.  NOTICES. Any notices, requests, demands, and other communications
provided for by this Plan shall be sufficient if in writing and delivered in
person or sent by registered or certified mail, postage prepaid, to a Covered
Employee at the last address the Covered Employee has filed in writing with the
Employers, or to the Employers at their main office, attention of the Board of
Directors.

     12.  EFFECT ON OTHER PLANS. Nothing in this Plan shall be construed to
limit the rights of the Covered Employees under the Employers' benefit plans,
programs or policies.

     13.  AMENDMENT OR TERMINATION OF PLAN. The Company may amend or terminate
this Plan at any time or from time to time; provided, however, that no such
amendment shall, without the consent of the Covered Employees, in any material
adverse way affect the rights of the Covered Employees, and no termination shall
be made without the written consent of the Covered Employees.

     14.  GOVERNING LAW. This Plan shall be construed under and be governed in
all respects by the laws of the Commonwealth of Massachusetts.

     15.  OBLIGATIONS OF SUCCESSORS. In addition to any obligations imposed by
law upon any successor to the Employers, the Employers will use their best
efforts to require any successor (whether direct or indirect, by purchase,
merger, consolidation or otherwise) to all or substantially all of the business
or assets of the Employers to expressly assume and agree to perform this Plan in
the same manner and to the same extent that the Employers would be required to
perform if no such succession had taken place.

Adopted: As of July 30, 1998

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