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                                                                  EXHIBIT 10.18

                               FIRST AMENDMENT TO
                              GSP OPTION AGREEMENT



          THIS FIRST AMENDMENT TO GSP OPTION AGREEMENT, dated as of May 21,
1997, is made by and between WESTFIELD CAPITAL CORPORATION FINANCE PTY. 
LIMITED, a corporation organized under the laws of New South Wales, Australia 
("Grantor"), and WESTFIELD AMERICA, INC., a Missouri corporation (formerly 
known as CenterMark Properties, Inc.) ("Grantee").

                             W I T N E S S E T  H :


          WHEREAS, the Grantor and Grantee are parties to that certain GSP 
Option Agreement (the "Original GSP Option Agreement"), dated as of July 1, 
1996, pursuant to which the Grantor granted to the Grantee the option to 
acquire all of the outstanding common stock of Westland Realty, Inc.; and

          WHEREAS, the Grantor and the Grantee desire to amend the Original 
GSP Option Agreement as set forth herein.

          NOW, THEREFORE, for good and valuable consideration, the receipt 
and sufficiency of which is hereby acknowledged, the Grantor and the Grantee 
agree as follows:

          1.   DEFINITIONS:  All capitalized terms used herein without 
definition shall have the respective meanings set forth in the Original GSP 
Option Agreement.

          2.   AMENDMENT TO SECTION 2.  Section 2 of the Original GSP Option 
Agreement is hereby amended by deleting such section in its entirety and 
substituting the following therefor:

               "2.  OPTION TERM.  

                     (a)  The Grantee's right to exercise the Option shall
               commence on the first business day after the date of delivery of
               the Valuation Notice (as such term is defined in Section 5.2(b))
               and shall continue until 5:00 p.m. (e.s.t.) on the 120th
               consecutive day thereafter (the "Option Period").

                     (b)  The Grantor shall deliver written notice (the
               "Stabilization Notice") to the Grantee, delivered in the manner
               provided in Section 16.5 hereof, upon the earlier to occur of the
               following events:

                       (i)  the completion and stabilization of the current
                    expansion of the property (as more generally described on
                    Exhibit A hereto) which shall be deemed to have occurred

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                    when 95% of the gross leasable area of the expansion
                    (excluding premises leased to anchor tenants) has been
                    leased to bona fide third party tenants; or 

                    (ii) the date 18 months after the Grantee receives written
                    notice, delivered as provided in Section 16.5, from the
                    Grantor stating that the construction of the expansion has
                    been substantially completed.

                     (c)  The valuation procedure resulting in the Valuation
               Notice shall commence upon the earlier to occur of the following
               events (the "Valuation Procedure Commencement Events"):

                       (i)   The Grantee's delivery of written notice to the
                    Grantor, delivered at any time after the Grantee's receipt
                    of the Stabilization Notice, stating that the Grantee has
                    elected to commence the valuation procedure; or

                       (ii)  January 3, 2000, as such date may be extended by
                    agreement of the Grantor and the Grantee;

               provided that in any such case the Grantee shall deliver written
               notice to the Grantor of its election to commence the valuation
               procedure prior to 5:00 p.m. (e.s.t.) on January 3, 2000.

          3.   AMENDMENT TO SECTION 5.1(B).  Section 5.1(b) of the Original GSP
Option Agreement is amended by deleting the reference to "Class B-2 common
stock" in the third line thereof and substituting "common stock" therefor.

          4.   AMENDMENT TO SECTION 5.2(A).  Section 5.2(a) of the Original GSP
Option Agreement is amended by deleting such section in its entirety and
substituting the following therefor:

                     "(a)  Promptly after the receipt by the Grantor of notice
                    from the Grantee under Section 2(c)(i) of the Grantee's
                    election to commence the valuation procedure, the Grantor
                    and the Grantee shall appoint Landauer Real Estate
                    Counselors ("Landauer") or such other independent real
                    estate appraiser as shall be agreed upon by the Grantor and
                    the Grantee as the appraiser to determine the fair market
                    value of the Property (the "Fair Market Value of the
                    Property").  Landauer or such other mutually agreed upon
                    appraiser shall be defined herein as the "Appraiser".  If
                    the Grantor and/or the Grantee shall desire to appoint
                    another appraiser but cannot agree on the identity of such
                    other appraiser for any reason or no reason within 15
                    business days of the date of the Grantee's notice under
                    Section 

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                    2(c), the Appraiser shall be Landauer.  The determination 
                    of the Fair Market Value of the Property determined by the 
                    Appraiser shall be binding upon the Grantor and the Grantee,
                    and shall be delivered by the Appraiser in writing to the 
                    Grantor and the Grantee within 30 days of the appointment of
                    the Appraiser."

          5.   AMENDMENT TO SECTION 16.1.  Section 16.1 of the Original GSP
Option Agreement is amended by deleting clause (iv) thereof in its entirety and
renumbering clause (v) to be clause (iv).

          6.   AMENDMENT TO SCHEDULE I.  Schedule I to the Original GSP Option
Agreement is hereby amended by substituting the Schedule I attached hereto
therefor so as to recognize that the $145,000,000 loan being made by the Grantee
to Westland Realty as of the date hereof may remain outstanding upon any
exercise of the Option.

          7.   AMENDMENT TO EXHIBIT A.  Exhibit A to the Original GSP Option
Agreement is hereby amended by substituting the Exhibit A attached hereto
therefor.

          8.   RATIFICATION.  Except as amended hereby, the Original GSP Option
Agreement is hereby ratified and remains in full force and effect.

          9.   COUNTERPARTS.  This Agreement may be executed in any number of
counterparts, each of which shall be effective only upon delivery and thereafter
shall be deemed an original, and all of which shall be taken to be one and the
same instrument with the same effect as if all parties hereto had all signed the
same signature page.  Any signature page of this Agreement may be detached from
any counterpart of this Agreement without impairing the legal effect of any
signatures thereon and may be attached to another counterpart of this Agreement
identical in form hereto but having attached to it one more additional signature
pages.

          10.  EFFECTIVE DATE.  This Agreement shall be effective as of the
closing of the initial public offering of common stock of the Grantee pursuant
to its Registration Statement on Form S-11 (No. 333-22731). 

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          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be executed as of the date first above written.

                         WESTFIELD AMERICA, INC.


                         By:  /s/ Richard Green
                            ----------------------------------------------
                            Name:  Richard Green
                            Title:  Co-President


                         WESTFIELD CAPITAL CORPORATION
                          FINANCE PTY. LIMITED


                         By:  /s/ Peter S. Lowy
                            ----------------------------------------------
                            Name:  Peter S. Lowy
                            Title:  Director

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                                   SCHEDULE I


                                 SUBSIDIARY DEBT


1.   $145,000,000 loan by Grantee to Westland Management, Inc. and Westfield
     Partners, Inc.

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                                    EXHIBIT A

                            DESCRIPTION OF EXPANSION

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