Exhibit 10.57

MODIFICATION AGREEMENT

Unsecured Loan

THIS
MODIFICATION AGREEMENT (Agreement) is dated as of October 23, 2007, by and between Wells Fargo Bank, National Association (Lender), and KBS LIMITED PARTNERSHIP, a Delaware limited partnership (Borrower).

RECITALS

A. Pursuant to the terms of a Loan Agreement
between Borrower and Lender dated July 24, 2007 (Loan Agreement), Lender made a loan to Borrower in the principal amount of Seventy Six Million Four Hundred Thousand and 00/100ths Dollars ($76,400,000.00) (Loan). The
Loan is evidenced by a promissory note dated as of the date of the Loan Agreement, executed by Borrower in favor of Lender, in the principal amount of the Loan (Note).

B. The Note, Loan Agreement, this Agreement, the other documents described in the Loan Agreement as Loan Documents together with all modifications and amendments thereto and any document required
hereunder, are collectively referred to herein as the Loan Documents.

C. By this Agreement, Borrower and Lender intend to modify and amend
certain terms and provisions of the Loan Documents.

NOW, THEREFORE, Borrower and Lender agree as follows:

1. CONDITIONS PRECEDENT. The following are conditions precedent to Lenders obligations under this Agreement:

1.1 Receipt and approval by Lender of the executed originals of this Agreement, and any and all other documents and agreements which are required pursuant to this
Agreement or which Lender has requested pursuant to the Loan Documents, in form and content acceptable to Lender;

1.2 Reimbursement to Lender by Borrower
of Lenders costs and expenses incurred in connection with this Agreement and the transactions contemplated hereby, including, without limitation, attorneys fees, and documentation costs and charges, whether such services are furnished by
Lenders employees or agents or by independent contractors;

1.3 The representations and warranties contained herein are true and correct;

1.4 All payments due and owing to Lender under the Loan Documents have been paid current as of the effective date of this Agreement; and

1.5 The payment to Lender of an extension fee in the amount of $14,785.00.

2. REPRESENTATIONS AND WARRANTIES. Borrower hereby represents and warrants that no breach or failure of condition has occurred, or would exist with notice or the lapse of time or both, under any of the Loan Documents, as modified by this
Agreement, and all representations and warranties herein are true and correct, which representations and warranties shall survive execution of this Agreement.

3. MODIFICATION OF LOAN DOCUMENTS. The Loan Documents are hereby supplemented and modified to incorporate the following, which shall supersede and prevail over any conflicting provisions of the Loan Documents:

3.1 Extension of Maturity Date. Effective as of October 24, 2007, the Maturity Date recited in the Note and Loan Agreement is hereby extended to November 24,
2007.



---

4. FORMATION AND ORGANIZATIONAL DOCUMENTS. Borrower has previously delivered to Lender all of the relevant formation and
organizational documents of Borrower, of the partners, members or joint venturers of Borrower (if any), and of all guarantors of Borrowers obligations under the Loan Agreement (if any), and all such formation documents remain in full force and
effect and have not been amended or modified since they were delivered to Lender. Borrower hereby certifies that: (i) the above documents are all of the relevant formation and organizational documents of Borrower; (ii) they remain in full
force and effect; and (iii) they have not been amended or modified since they were previously delivered to Lender.

5. NON-IMPAIRMENT. Except as
expressly provided herein, nothing in this Agreement shall alter or affect any provision, condition, or covenant contained in any Loan Document or affect or impair any rights, powers, or remedies of Lender, it being the intent of the parties hereto
that the provisions of the Loan Documents shall continue in full force and effect except as expressly modified hereby.

6. MISCELLANEOUS. This Agreement
and the other Loan Documents shall be governed by and interpreted in accordance with the laws of the State of California, except if preempted by federal law. In any action brought or arising out of this Agreement or the other Loan Documents,
Borrower, and the general partners, members and joint venturers of Borrower (if any), hereby consent to the jurisdiction of any federal or state court having proper venue within the State of California and also consent to the service of process by
any means authorized by California or federal law. The headings used in this Agreement are for convenience only and shall be disregarded in interpreting the substantive provisions of this Agreement. All capitalized terms used herein, which are not
defined herein, shall have the meanings given to them in the other Loan Documents. Time is of the essence of each term of the Loan Documents, including this Agreement. If any provision of this Agreement or any of the other Loan Documents shall be
determined by a court of competent jurisdiction to be invalid, illegal or unenforceable, that portion shall be deemed severed from this Agreement and the remaining parts shall remain in full force as though the invalid, illegal, or unenforceable
portion had never been a part thereof.

7. INTEGRATION; INTERPRETATION. The Loan Documents, including this Agreement, contain or expressly incorporate by
reference the entire agreement of the parties with respect to the matters contemplated therein and supersede all prior negotiations or agreements, written or oral. The Loan Documents shall not be modified except by written instrument executed by all
parties. Any reference to the Loan Documents includes any amendments, renewals or extensions now or hereafter approved by Lender in writing.

8. EXECUTION
IN COUNTERPARTS. To facilitate execution, this document may be executed in as many counterparts as may be convenient or required. It shall not be necessary that the signature of, or on behalf of, each party, or that the signature of all persons
required to bind any party, appear on each counterpart. All counterparts shall collectively constitute a single document. It shall not be necessary in making proof of this document to produce or account for more than a single counterpart containing
the respective signatures of, or on behalf of, each of the parties hereto. Any signature page to any counterpart may be



---

detached from such counterpart without impairing the legal effect of the signatures thereon and thereafter attached to another counterpart identical thereto
except having attached to it additional signature pages.

IN WITNESS WHEREOF, Borrower and Lender have caused this Agreement to be duly executed as of the
date first above written.

LENDER



|                                                        |  |                                                   
|------------------------------------------------------- |  | --------------------------------------------------
|Wells Fargo Bank, National Association                 
|                                                        | 
|By:                                                     |  | /s/ John A. Ferguson                              
|                                                        |  | John A. Ferguson, Senior Vice President           
|                                                       
|Lenders Address:                                      
|Real Estate Group (AU #02955)                          
|2030 Main Street                                       
|Suite 800                                              
|Irvine, CA 92614                                       
|                                                        | 
|Attn:                                                   |  | Rhonda Friedly                                    
|                                                       
|BORROWER                                             
|                                                       
|KBS LIMITED PARTNERSHIP, a Delaware limited partnership
|                                                        | 
|By:                                                     |  | KBS REAL ESTATE INVESTMENT TRUST, INC., a         
|                                                        |  | Maryland corporation, General Partner             
|                                                        | 
|By:                                                     |  | /s/ Charles J. Schreiber                          
|                                                        |  | Charles J. Schreiber, Jr., Chief Executive Officer
|                                                       
|Borrowers Address:                                    
|C/O KBS Realty Advisors                                
|620 Newport Center Drive, Suite 1300                   
|Newport Beach, CA 92660                                
|                                                        | 
|Attn:                                                   |  | Stacie Yamane                                     

GUARANTORS CONSENT

The undersigned (Guarantor) consents to the foregoing Modification Agreement and the transactions contemplated thereby and reaffirms its obligations under the Repayment Guaranty (Guaranty) dated July 24, 2007.
Guarantor further reaffirms that its obligations under the Guaranty are separate and distinct from Borrowers obligations.

Agreed and Acknowledged:

Dated as of: October 23, 2007



---

GUARANTOR



|                                                               |  |                                                   
|-------------------------------------------------------------- |  | --------------------------------------------------
|KBS REAL ESTATE INVESTMENT TRUST, INC., a Maryland corporation
|                                                               | 
|By:                                                            |  | /s/ Charles J. Schreiber                          
|                                                               |  | Charles J. Schreiber, Jr., Chief Executive Officer