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EXHIBIT 3.1

FOURTH AMENDMENT TO

THIRD AMENDED AND RESTATED


AGREEMENT OF LIMITED PARTNERSHIP


OF EOP OPERATING LIMITED PARTNERSHIP


THIS FOURTH AMENDMENT(this Amendment)
TO THIRD AMENDED AND RESTATED AGREEMENT OF LIMITED
PARTNERSHIP OF EOP OPERATING LIMITED PARTNERSHIP(theAgreement), dated May 25, 2004,
is entered into by EQUITY OFFICE PROPERTIES TRUST, a
Maryland real estate investment trust, as the general partner
(theGeneral Partner) of EOP Operating Limited
Partnership, a Delaware limited partnership (the
Partnership), for itself and on behalf of the
Limited Partners of the Partnership.

WHEREAS,on
May 25, 2004, pursuant that certain contribution agreement
dated April 20, 2004 (the Contribution
Agreement), Angelview Investors Limited Partnership
(Angelview) contributed property to CA-Orange
Limited Partnership in exchange for units of limited partnership
interest in the Partnership (the Angelview
Units);

WHEREAS,pursuant to
the Contribution Agreement, Angelview has elected to become a
Part II Protected Partner pursuant to the Agreement, thereby
agreeing to restore, upon certain conditions, all or a portion
of any deficit balance in its Capital Account; and

WHEREAS,the General
Partner desires to amend the Agreement in order to designate
Angelview as a Part II Protected Partner.

NOW, THEREFORE,in
consideration of the premises set forth above and for other good
and valuable consideration, the receipt and sufficiency of which
hereby are acknowledged, the General Partner hereby amends the
Agreement as follows:



| |                                                                                                                                                                                                                                                                                                                                                                
| | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | 1.Addition of
    Exhibit E-10 to the Agreement. Exhibit E-10 to the
    Agreement is hereby created and made part of the Agreement by
    incorporating the content of Exhibit A attached to this
    Amendment, which sets forth specific additional agreements
    regarding certain additional rights and obligations of Angelview
    and the Partnership.
|
| | 2.Addition to
    Exhibit E to the Agreement. Exhibit E to the
    Agreement is hereby modified by inserting, at the end of the
    Exhibit,                                                                                                                                                                                                                   

(10) Protected Amount is as provided for
in Exhibit E-10.



| |                                                                                                                                                                                                                                                                                                                                                                                                   
| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | 3.Defined
    Terms. All capitalized terms used in this Amendment and not
    otherwise defined shall have the meanings assigned to them in
    the Agreement. Except as modified by this Amendment and
    Exhibit A hereto, all terms and conditions of the Agreement
    shall remain in full force and effect, which terms and
    conditions the General Partner hereby ratifies and affirms.
|
| | 4.Time Is of the
    Essence. Time is of the essence as to each and every
    provision of this Amendment.                                                                                                                                                                                                                                                                                        



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IN WITNESS WHEREOF,the undersigned has executed this Amendment as of the date first
set forth above.



| |                                                                                                                                                                                     
| | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | EQUITY OFFICE PROPERTIES TRUST, a Maryland real
    estate investment trust, the General Partner of EOP Operating
    Limited Partnership and on behalf of existing Limited Partners



| |     |                 
| | --- | ----------------
| | By: | /s/ RICHARD BERK

| |                                
| | -------------------------------
| |                                
| | Name:     Richard Berk         
| | Title:       Vice
    President



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EXHIBIT A

EXHIBIT E-10

(Angelview Investors  CA Orange
Agreement)

Background

On May 25, 2004, in connection with the
closing of the transactions contemplated by the Contribution
Agreement by and among ANGELVIEW INVESTORS LIMITED PARTNERSHIP,
an Illinois limited partnership
(Contributor), the Partnership, and
CA-ORANGE LIMITED PARTNERSHIP, a Delaware limited partnership
that is directly and indirectly wholly-owned by the Partnership,
dated May 25, 2004 (the Contribution
Agreement), Contributor received 1930 Class B Units
of limited Partnership Interest in the Partnership (the
Units), based on a price per Unit of
$25.89, in exchange for its interest in the
Property, as defined in the Contribution Agreement.
In connection with the issuance of the Units, the Fourth
Amendment, dated May 25, 2004 (the Fourth
Amendment) to the Third Amended and Restated
Agreement of Limited Partnership of EOP (the
Agreement), was executed adding this
Exhibit E-10 to the Agreement, setting forth specific
agreement regarding additional rights and obligations of
Contributor and the Partnership.

All Capitalized terms used and not otherwise
defined in this Exhibit E-10 have the meanings assigned in
the Agreement or the Fourth Amendment, as applicable.

Specific Agreement

Contributors Obligation to Restore
Deficit Capital Accounts.Contributor
shall be a Part II Protected Partner pursuant to the Agreement,
with a Protected Amount not in excess of $23,354,857.00;
provided that Contributor has delivered to the General Partner,
an Election to Undertake Obligation to Restore Deficit Capital
Account (the DRO Election), in the
form attached to the Contribution Agreement as Exhibit B
thereof. Notwithstanding any obligation of the Partnership
referred to in the Contribution Agreement, the Partnership shall
not be obligated to maintain any level of indebtedness that
qualifies as a Recourse Liability (as defined in the Agreement).
Neither the Partnership nor the General Partner has or will make
any representation or warranty to Contributor that the DRO
Election will be effective to cause Contributor to be considered
to bear the economic risk of loss with respect to
indebtedness of the Operating Partnership for purposes of either
Section 752 or Section 465 of the Code. Upon becoming
effective, the DRO Election shall be irrevocable, cannot be
reduced, and shall be binding upon successive transferees of the
Contributor, except as provided in Section 13.3.D of the
Agreement.