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                                                                    EXHIBIT 10.4

                 THIRD AMENDMENT TO PURCHASE AND SALE AGREEMENT

        THIS THIRD AMENDMENT TO PURCHASE AND SALE AGREEMENT ("AMENDMENT") is
entered into to be effective as of the 9th day of August, 2004, by and between
HIPPO PROPERTIES LLC, a Delaware limited liability company ("Seller"), and
HARVARD PROPERTY TRUST, LLC, a Delaware limited liability company ("PURCHASER").
All capitalized terms used herein and not otherwise defined herein shall have
the meanings ascribed to them in the Purchase Agreement (defined below).

                              W I T N E S S E T H:

        WHEREAS, Seller and Purchaser previously entered into that certain
Purchase and Sale Agreement dated as of April 30, 2004, as amended by that
certain First Amendment to Purchase and Sale Agreement dated May 20, 2004, and
that certain Second Amendment to Purchase and Sale Agreement dated July 19, 2004
(collectively, the "PURCHASE AGREEMENT"), pursuant to which Seller agreed to
sell to Purchaser and Purchaser agreed to purchase the Property described
therein.

        WHEREAS, Seller and Purchaser now desire to amend the Purchase Agreement
in certain respects, as hereinafter set forth.

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

        1.      EXTENSION OF CLOSING DATE. Seller and Purchaser agree that the
Date of Closing shall be August 10, 2004.

        2.      EFFECT OF AMENDMENT. This Amendment modifies and amends the
Purchase Agreement and the terms and provisions hereof shall supersede and
control over any contrary or conflicting terms and provisions set forth in the
Purchase Agreement. The Purchase Agreement, as amended by this Amendment,
remains in full force and effect.

        3.      COUNTERPARTS. To facilitate execution of this Amendment, this
Amendment may be executed in multiple counterparts, each of which, when
assembled to include an original signature for each party contemplated to sign
this Amendment, will constitute a complete and fully executed original. All such
fully executed original counterparts will collectively constitute a single
agreement.

        4.      FACSIMILE SIGNATURES. In order to expedite the transaction
contemplated herein, telecopied or facsimile signatures may be used in place of
original signatures on this Amendment. Seller and Purchaser intend to be bound
by the signatures on the telecopied document, are aware that the other party
will rely on the telecopied signatures, and hereby waive any defenses to the
enforcement of the terms of this Amendment based on the form of signature.

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        IN WITNESS WHEREOF, the parties hereto have executed this Amendment to
be effective the date and year first above written.

                                    SELLER:

                                    HIPPO PROPERTIES LLC,
                                    a Delaware limited liability company

                                    By: Hippo Ventures LLC, Manager

                                        By: Hippo Management LLC, Manager

                                            By:_________________________________
                                            Name:_______________________________
                                            Title:______________________________



                                    PURCHASER:

                                    HARVARD PROPERTY TRUST, LLC,
                                    a Delaware limited liability company


                                    By:_________________________________
                                    Name:_______________________________
                                    Title:______________________________





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