Exhibit 10.1

AMENDMENT TO REVOLVING
CREDIT AGREEMENT

     THIS AMENDMENT TO REVOLVING CREDIT AGREEMENT (this “Amendment”) is made as
of December 14, 2004, by and among EOP OPERATING LIMITED PARTNERSHIP (the
“Borrower”), the BANKS listed on the signature pages hereof, and BANK OF
AMERICA, N.A., as Administrative Agent for the Banks.

W I T N E S S E T H:

     WHEREAS, the Borrower and the Banks have entered into the Revolving Credit
Agreement, as of May 9, 2003 (the “Credit Agreement”); and

     WHEREAS, the parties desire to modify the Credit Agreement upon the terms
and conditions set forth herein.

     NOW THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties do hereby agree as
follows:

1. Definitions. All capitalized terms not otherwise defined herein shall have
the meanings ascribed to them in the Credit Agreement.

2. Amendments to Definitions.

(a) The definition of “FFO” is hereby deleted and the following substituted
therefore:

“FFO” means “funds from operations” as defined in accordance with resolutions
adopted by the Board of Governors of the National Association of Real Estate
Investment Trusts as in effect from time to time; provided that FFO shall (i) be
based on net income before payment of distributions to holders of preferred
partnership units in the Borrower and distributions necessary to pay holders of
preferred stock of Guarantor, and (ii) at all times exclude (a) charges for non-

 

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cash impairments taken in accordance with GAAP, and (b) non-recurring charges.

(b) The definition of “Joint Venture Subsidiary” is hereby deleted and the
following substituted therefore:

“Joint Venture Subsidiary” means any entity (other than a Financing Partnership)
in which (i) a Joint Venture Parent owns at least 20% of the economic interests
and (ii) the sale or financing of any Property owned by such Joint Venture
Subsidiary is substantially controlled by a Joint Venture Parent, subject to
customary provisions set forth in the organizational documents of such Joint
Venture Subsidiary with respect to refinancings or rights of first refusal
granted to other members of such Joint Venture Subsidiary. For purposes of the
preceding sentence, the sale or financing of a Property owned by a Joint Venture
Subsidiary shall be deemed to be substantially controlled by a Joint Venture
Parent if such Joint Venture Parent has the ability to exercise a buy-sell right
in the event of a disagreement regarding the sale or financing of such Property.
In addition, the relationship of a Joint Venture Parent as a tenant in common in
any asset with other tenants in common in the same asset shall be treated as if
such relationship were a general partnership for purposes of this definition.

(c) The definition of “Total Asset Value” is hereby amended by inserting the
phrase “exclusive of Properties, if any, that shall have produced a negative
EBITDA for the applicable period,”, after the words “for any Properties (other
than Unimproved Assets and Land under Development) owned by Borrower, any
Consolidated Subsidiary or Investment Affiliate which was neither acquired nor
disposed of by Borrower, a Consolidated Subsidiary or an Investment Affiliate in
the Fiscal Quarter most recently ended,”.

(d) For purposes of the definitions of “Unencumbered Asset Value” and
“Unencumbered Net Operating Income”, a Joint Venture Subsidiary also shall be
deemed to include any entity (other than a Financing Partnership) in which a

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Qualified Joint Venture Partner owns the balance of the interests. In addition,
clause (ii) of the definition of “Unencumbered Asset Value” is hereby amended by
inserting the phrase “exclusive of Qualifying Unencumbered Properties, if any,
that shall have produced a negative EBITDA for the applicable period,”, after
the words “for any Qualifying Unencumbered Properties which were neither
acquired or disposed of by Borrower, a Financing Partnership or a Joint Venture
Subsidiary in the Fiscal Quarter most recently ended”.

(e) The following definition shall be added after the definition of “Qualified
Institution”: “‘Qualified Joint Venture Partner’ means (a) pension funds,
insurance companies, banks, investment banks or similar institutional entities,
each with significant experience in making investments in commercial real
estate, and (b) commercial real estate companies of similar quality and
experience.”

3. Leverage. The reference in Sections 5.8(a) and 5.8(f) to “0.55:1” is hereby
deleted and “0.60:1” is substituted therefore.

4. Dividends. The reference in Section 5.8(i) to “90%” is hereby deleted and
“95%” substituted therefore. For purposes of Section 5.8(i), partnership
distributions shall include all distributions to common and preferred
unitholders of Borrower.

5. Calculations. Section 5.8(l) is hereby deleted and the following substituted
therefore: “(l) Calculation. With the exception of the calculation required
pursuant to Section 5.8(i), calculations of ratios and financial requirements
shall be made as of the last day of each Fiscal Quarter. All calculations
required pursuant to this Section 5.8 shall exclude the effect of any
consolidation required by FIN 46(R).

6. Effective Date. This Amendment shall become effective upon receipt by the
Administrative Agent of counterparts hereof signed by the Borrower

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and the Required Banks (the date of such receipt being deemed the “Effective
Date”).

7. Representations and Warranties. Borrower hereby represents and warrants that
as of the Effective Date, all the representations and warranties set forth in
the Credit Agreement, as amended hereby (other than representations and
warranties that expressly speak as of a different date), are true and complete
in all material respects.

8. Entire Agreement. This Amendment constitutes the entire and final agreement
among the parties hereto with respect to the subject matter hereof and there are
no other agreements, understandings, undertakings, representations or warranties
among the parties hereto with respect to the subject matter hereof except as set
forth herein.

9. Governing Law. This Amendment shall be governed by, and construed in
accordance with, the law of the State of New York.

10. Counterparts. This Amendment may be executed in any number of counterparts,
all of which taken together shall constitute one and the same agreement, and any
of the parties hereto may execute this Amendment by signing any such
counterpart.

11. Headings, Etc. Section or other headings contained in this Amendment are for
reference purposes only and shall not in any way affect the meaning or
interpretation of this Amendment.

12. No Further Modifications. Except as modified herein, all of the terms and
conditions of the Credit Agreement, as modified hereby shall remain in full
force and effect and, as modified hereby, the Borrower confirms and ratifies all
of the terms, covenants and conditions of the Credit Agreement in all respects.

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     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed by their respective authorized officers as of the day and year
first above written.

              EOP OPERATING LIMITED PARTNERSHIP,     a Delaware limited
partnership
 
       

  By:   Equity Office Properties Trust, a Maryland real
estate investment trust, its general partner
 
       

  By:   /s/ Marsha C. Williams

     

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  Name:   Marsha C. Williams

  Title:   Executive Vice President and Chief Financial Officer

FOR PURPOSES OF AGREEING TO BE
BOUND BY THE PROVISIONS OF
THIS AMENDMENT:

EQUITY OFFICE PROPERTIES TRUST, a Maryland
real estate investment trust

         
By:
  /s/ Marsha C. Williams    

 

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  Name: Marsha C. Williams    

  Title: Executive Vice President and Chief Financial Officer    

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              BANK OF AMERICA, N.A., as Administrative     Agent, as Swingline
Lender, and as a Bank
 
       

  By:   /s/ Eyal Namordl

     

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  Name:   Eyal Namordl

  Title:   Vice President

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              JPMORGAN CHASE BANK, N.A., as Syndication     Agent and as a Bank
 
       

  By:   /s/ Marc E. Costantino

     

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  Name:   Marc E. Costantino

  Title:   Vice President

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              UBS AG, CAYMAN ISLANDS BRANCH, as Senior Managing     Agent and as
a Bank
 
       

  By:   /S/ Wilfred V. Saint

     

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  Name:   Wilfred V. Saint

  Title:   Director Banking Products Services, US
 
       

  By:   /s/ Joselin Fernandes

     

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  Name:   Joselin Fernandes

  Title:   Associate Director Banking Products Services, US

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              PNC BANK, NATIONAL ASSOCIATION, as Senior Managing     Agent and
as a Bank
 
       

  By:   /s/ Michael E. Smith

     

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  Name:   Michael E. Smith

  Title:   Senior Vice President

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              EUROHYPO AG, NEW YORK BRANCH, as     Managing Agent and as a Bank
 
       

  By:   /s/ Alfred Koch

     

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  Name:   Alfred Koch

  Title:   Executive Director
 
       

  By:   /s/ Stephen Cox

     

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  Name:   Stephen Cox

  Title:   Vice President
 
       

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              U.S. BANK NATIONAL ASSOCIATION, as Senior     Managing Agent and
as a Bank
 
       

  By:   /s/ Megan McBride

     

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  Name:   Megan McBride

  Title:   Senior Vice President
 
       

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              JPMORGAN CHASE BANK, N.A.(successor by     merger to Bank One,
NA), as Documentation Agent     and as a Bank
 
       

  By:   /s/ Marc E. Costantino

     

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  Name:   Marc E. Costantino

  Title:   Vice President

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              DEUTSCHE BANK TRUST COMPANY     AMERICAS, as Co-Agent and as a
Bank
 
       

  By:   /s/ Steven P. Lapham

     

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  Name:   Steven P. Lapham

  Title:   Managing Director
 
       

  By:   /s/ Brenda Casey

     

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  Name:   Brenda Casey

  Title:   Vice President

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              NATIONAL AUSTRALIA BANK LIMITED, as Co-     Agent and as a Bank
 
       

  By:   /s/ Thomas Matesich

     

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  Name:   Thomas Matesich

  Title:   Senior Vice President

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              THE BANK OF NOVA SCOTIA, NEW YORK     AGENCY, as Senior Managing
Agent and as a Bank
 
       

  By:   /s/ R. H. Boese

     

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  Name:   R.H. Boese

  Title:   Managing Director

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              WACHOVIA BANK, N.A., as Managing Agent and     as a Bank
 
       

  By:   /s/ David Blackman

     

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  Name:   David Blackman

  Title:   Director

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              UNION BANK OF CALIFORNIA, N.A., as Co-     Agent and as a Bank
 
       

  By:   /s/ Gary Roberts

     

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  Name:   Gary Roberts

  Title:   Vice President

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              LASALLE BANK NATIONAL ASSOCIATION,     as Managing Agent and as a
Bank
 
       

  By:   /s/ Brad Feine

     

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  Name:   Brad Feine

  Title:   Commercial Banking Officer

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              MORGAN STANLEY BANK, as Senior Managing     Agent and as a Bank
 
       

  By:   /s/ Daniel Twenge

     

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  Name:   Daniel Twenge

  Title:   Vice President Morgan Stanley Bank

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              CREDIT SUISSE FIRST BOSTON, ACTING     THROUGH ITS CAYMAN ISLANDS
BRANCH as     Managing Agent and as a Bank
 
       

  By:   /s/ Cassandra Droogan

     

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  Name:   Cassandra Droogan

  Title:   Associate
 
       

  By:   /s/ Bill O'Daly

     

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  Name:   Bill O'Daly

  Title:   Director

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              CITICORP NORTH AMERICA, INC., as Managing     Agent and as a Bank
 
       

  By:   /s/ Michael Chiopak

     

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  Name:   Michael Chiopak

  Title:   Vice President

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              MERRILL LYNCH BANK USA, as Managing     Agent and as a Bank
 
       

  By:   /s/ Louis Alder

     

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  Name:   Louis Alder

  Title:   Director

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              THE BANK OF NEW YORK, as a Bank
 
       

  By:   /s/ Rick Laudisi

     

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  Name:   Rick Laudisi

  Title:   Vice President

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              THE NORTHERN TRUST COMPANY, as a Bank
 
       

  By:   /s/ Eleanor Grumman

     

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  Name:   Eleanor Grumman

  Title:   Vice President

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              CHANG HWA COMMERCIAL BANK, LTD., LOS     ANGELES. BRANCH, as a
Bank
 
       

  By:   /s/ Chen-Yu Chen

     

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  Name:   Chen-Yu Chen

  Title:   Vice President & General Manager

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