Exhibit 21.1



|                                                |  |                      
|----------------------------------------------- |  | ---------------------
|Subsidiary                                      |  | State of Organization
|101 Carnegie Center Associates                  |  | New Jersey           
|17M Associates                                  |  | District of Columbia 
|191 Spring Street Trust                         |  | Massachusetts        
|206 Associates Limited Partnership              |  | New Jersey           
|210 Associates Limited Partnership              |  | New Jersey           
|211 Associates Limited Partnership              |  | New Jersey           
|30 Shattuck Road LLC                            |  | Delaware             
|40-46 Harvard Street Trust                      |  | Massachusetts        
|46th & Eighth Associates LLC                    |  | Delaware             
|90 Church Street Limited Partnership            |  | Delaware             
|91 Hartwell Avenue Trust                        |  | Massachusetts        
|92 Hayden Avenue Trust                          |  | Massachusetts        
|738 Eighth Avenue LLC                           |  | Delaware             
|AJ Lot 2R Financing LLC                         |  | Delaware             
|AJ Lot 2R LLC                                   |  | Delaware             
|AJ Lot 3R Financing LLC                         |  | Delaware             
|AJ Lot 3R LLC                                   |  | Delaware             
|AJ Lot 4R Financing LLC                         |  | Delaware             
|AJ Lot 4R LLC                                   |  | Delaware             
|Annapolis Junction NFM LLC                      |  | Delaware             
|Big Apple Associates Limited Partnership        |  | Delaware             
|Billerica Road LLC                              |  | Delaware             
|Billerica Road Member LLC                       |  | Delaware             
|Boston Properties LLC                           |  | Delaware             
|Boston Properties Management, Inc.              |  | Delaware             
|Boston Properties Management LLC                |  | Delaware             
|Boston Properties Office Value-Added Fund, L.P. |  | Delaware             
|Boston Properties TRS, Inc.                     |  | Delaware             
|BP-AJ LLC                                       |  | Delaware             
|BP 103 Fourth Avenue LLC                        |  | Delaware             
|BP 111 Huntington Ave LLC                       |  | Delaware             
|BP 1330 Connecticut Avenue LLC                  |  | Delaware             
|BP 1333 New Hampshire Avenue LLC                |  | Delaware             
|BP 140 Kendrick Street LLC                      |  | Delaware             
|BP 140 Kendrick Street Property LLC             |  | Delaware             
|BP 20 F Street Limited Partnership              |  | Delaware             
|BP 201 Spring Street LLC                        |  | Delaware             
|BP 280 Park Avenue LLC                          |  | Delaware             
|BP 280 Park Avenue Mezzanine LLC                |  | Delaware             
|BP 303 Almaden Associates LLC                   |  | Delaware             
|BP 399 Park Avenue LLC                          |  | Delaware             
|BP 599 Lexington Avenue LLC                     |  | Delaware             
|BP 99 Third Avenue LLC                          |  | Delaware             
|BP Almaden Associates LLC                       |  | Delaware             
|BP Atlantic Blvd LLC                            |  | Delaware             
|BP Belvidere LLC                                |  | Delaware             
|BP Cambridge Center Residential LLC             |  | Delaware             
|BP Crane Meadow, L.L.C.                         |  | Delaware             
|BP East Garage LLC                              |  | Delaware             
|BP EC1 Holdings LLC                             |  | Delaware             



---

|                                               |  |                      
|---------------------------------------------- |  | ---------------------
|Subsidiary                                     |  | State of Organization
|BP EC2 Holdings LLC                            |  | Delaware             
|BP EC3 Holdings LLC                            |  | Delaware             
|BP EC4 Holdings LLC                            |  | Delaware             
|BP Five CC LLC                                 |  | Delaware             
|BP Four CC LLC                                 |  | Delaware             
|BP Fourth Avenue, L.L.C.                       |  | Delaware             
|BP Gateway Center LLC                          |  | Delaware             
|BP Hotel LLC                                   |  | Delaware             
|BP II LLC                                      |  | Delaware             
|BP III LLC                                     |  | Delaware             
|BP Kingstowne Office Building K LLC            |  | Delaware             
|BP Kingstowne Office Building T LLC            |  | Delaware             
|BP Kingstowne Theatre LLC                      |  | Delaware             
|BP Management Sub LLC                          |  | Delaware             
|BP Management, L.P.                            |  | Delaware             
|BP MV Research Park LLC                        |  | Delaware             
|BP MV Technology Park LLC                      |  | Delaware             
|BP New Dominion Technology Office Park II, LLC |  | Delaware             
|BP North First LLC                             |  | Delaware             
|BP Office Fund REIT, Inc.                      |  | Maryland             
|BP Office Value-Added LLC                      |  | Delaware             
|BP Prospect Place LLC                          |  | Delaware             
|BP Prucenter Acquisition LLC                   |  | Delaware             
|BP Prucenter Development LLC                   |  | Delaware             
|BP Prucenter Exeter LLC                        |  | Delaware             
|BP Prucenter Fairfield LLC                     |  | Delaware             
|BP Realty New Jersey LLC                       |  | New Jersey           
|BP Realty Washington LLC                       |  | Delaware             
|BP Reston Eastgate LLC                         |  | Delaware             
|BP Russia Wharf LLC                            |  | Delaware             
|BP Seven Cambridge Center LLC                  |  | Delaware             
|BP Supermarket LLC                             |  | Delaware             
|BP Third Avenue LLC                            |  | Delaware             
|BP Times Square Tower Mezzanine LLC            |  | Delaware             
|BP Weston Quarry LLC                           |  | Delaware             
|BP Zanker Road LLC                             |  | Delaware             
|BP/CG Member I LLC                             |  | Delaware             
|BP/CG Member II LLC                            |  | Delaware             
|BP/CG Member III LLC                           |  | Delaware             
|BP/CGCenter Acquisition Co. LLC                |  | Delaware             
|BP/CGCenter I LLC                              |  | Delaware             
|BP/CGCenter II LLC                             |  | Delaware             
|BP/CGCenter MM LLC                             |  | Delaware             
|BP/CGCenter MM2 LLC                            |  | Delaware             
|BP/CRF 901 New York Avenue LLC                 |  | Delaware             
|BP/DC Properties, Inc.                         |  | Maryland             
|BP/DC REIT LLC                                 |  | Delaware             
|Broad Run Building E LLC                       |  | Delaware             
|Cambridge Center North Trust                   |  | Massachusetts        
|Cambridge Center West Garage LLC               |  | Delaware             
|Cambridge Center West Trust                    |  | Massachusetts        
|Carnegie 214 Associates Limited Partnership    |  | New Jersey           



---

|                                                             |  |                      
|------------------------------------------------------------ |  | ---------------------
|Subsidiary                                                   |  | State of Organization
|Carnegie 504 Associates                                      |  | New Jersey           
|Carnegie 506 Associates                                      |  | New Jersey           
|Carnegie 508 Associates                                      |  | New Jersey           
|Carnegie 510 Associates, L.L.C.                              |  | Delaware             
|Carnegie Center Associates                                   |  | New Jersey           
|Circle Star LLC                                              |  | Delaware             
|CRF Met Square LLC                                           |  | Delaware             
|Discovery Square, L.L.C.                                     |  | Delaware             
|Downtown Boston Properties Trust                             |  | Massachusetts        
|Elandzee Trust                                               |  | Massachusetts        
|Eleven Cambridge Center Trust                                |  | Massachusetts        
|Embarcadero Center Associates                                |  | California           
|Embarcadero Center, Inc.                                     |  | California           
|Four Embarcadero Center Venture                              |  | California           
|Fourteen Cambridge Center Trust                              |  | Massachusetts        
|Gateway Center LLC                                           |  | Delaware             
|Gladden Properties LLC                                       |  | Delaware             
|Hayden Office Trust                                          |  | Massachusetts        
|IXP, LLC                                                     |  | Vermont              
|Jones Road Development Associates LLC                        |  | Delaware             
|KEG I Associates, LLC                                        |  | Delaware             
|Lexreal Associates Limited Partnership                       |  | New York             
|LKE BP Fourth Avenue Limited Partnership                     |  | Massachusetts        
|Mall Road Trust                                              |  | Massachusetts        
|Market Square North Associates Limited Partnership           |  | Delaware             
|MBZ-Lex Trust                                                |  | Massachusetts        
|MGA Virginia 85-1 Limited Partnership                        |  | Virginia             
|MGA Virginia 86-1 Limited Partnership                        |  | Virginia             
|MGA Virginia 86-2 Limited Partnership                        |  | Virginia             
|Montgomery Village Avenue Joint Venture Limited Partnership  |  | Maryland             
|Montvale LLC                                                 |  | Maryland             
|New Dominion Technology Corp.                                |  | Delaware             
|New Dominion Technology Park II LLC                          |  | Delaware             
|New Dominion Technology Park LLC                             |  | Delaware             
|North First EAT LLC                                          |  | Delaware             
|No. 1 Times Square Development LLC                           |  | Delaware             
|No. 5 Times Square Development LLC                           |  | Delaware             
|Ocean View Development Company Limited Partnership           |  | District of Columbia 
|One Cambridge Center Trust                                   |  | Massachusetts        
|One Embarcadero Center Venture                               |  | California           
|One Freedom Square, L.L.C.                                   |  | Delaware             
|Princeton 202 Associates Limited Partnership                 |  | New Jersey           
|Princeton Childcare Associates Limited Partnership           |  | New Jersey           
|RBP 45thAssociates LLC                                       |  | New York             
|Reston Corporate Center Limited Partnership                  |  | Virginia             
|Reston Streets LLC                                           |  | Delaware             
|Reston Town Center Office Park Phase One Limited Partnership |  | Virginia             
|Reston VA 939, L.L.C.                                        |  | Delaware             
|Russia Wharf Ground Tenant LLC                               |  | Delaware             
|School Street Associates Limited Partnership                 |  | District of Columbia 
|SCV Partners                                                 |  | New Jersey           
|South of Market LLC                                          |  | Delaware             



---

|                                                   |  |                      
|-------------------------------------------------- |  | ---------------------
|Subsidiary                                         |  | State of Organization
|South of Market Garage LLC                         |  | Delaware             
|Springfield 6601 LLC                               |  | Delaware             
|Springfield Metro Center II, LLC                   |  | Delaware             
|Springfield Parcel C LLC                           |  | Delaware             
|Square 407 Limited Partnership                     |  | District of Columbia 
|Stony Brook Associates LLC                         |  | Delaware             
|Ten Cambridge Center Trust                         |  | Massachusetts        
|The Double B Partnership                           |  | Massachusetts        
|The Double B Trust                                 |  | Massachusetts        
|The Metropolitan Square Associates LLC             |  | District of Columbia 
|Three Cambridge Center Trust                       |  | Massachusetts        
|Three Embarcadero Center Venture                   |  | California           
|Times Square Tower Associates LLC                  |  | Delaware             
|Tower Oaks Financing LLC                           |  | Delaware             
|Tracer Lane Trust II                               |  | Massachusetts        
|Two Cambridge Center Trust                         |  | Massachusetts        
|Two Freedom Square, L.L.C.                         |  | Delaware             
|Washingtonian North Associates Limited Partnership |  | Maryland             
|Wisconsin Place Office Borrower LLC                |  | Delaware             
|Wisconsin Place Office LLC                         |  | Delaware             
|Wisconsin Place Office Manager LLC                 |  | Delaware             
|Wisconsin Place Retail LLC                         |  | Delaware             
|Worldgate Member LLC                               |  | Delaware             
|Worldgate Plaza LLC                                |  | Delaware             
|WP Borrower LLC                                    |  | Delaware             
|WP Trust                                           |  | Massachusetts        
|WP Project Developer LLC                           |  | Delaware             
|Zee Bee Trust II                                   |  | Massachusetts        
|Zee Em Trust II                                    |  | Massachusetts