EXHIBIT 12.1



BOSTON PROPERTIES LIMITED PARTNERSHIP

CALCULATION OF RATIOS OF EARNINGS TO COMBINED FIXED CHARGES

AND PREFERRED DISTRIBUTIONS



Boston Properties Limited Partnerships ratios of
earnings to combined fixed charges and preferred distributions for the five years ended December 31, 2004 were as follows:



|                                                                                                                                                                                                                                                                                                        |  |                         |         |   |      |   |         |      |  |   |         |   |  |      |         |   |  |   |         |  
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |  | ----------------------- | ------- | - | ---- | - | ------- | ---- |  | - | ------- | - |  | ---- | ------- | - |  | - | ------- | -
|                                                                                                                                                                                                                                                                                                        |  | Year Ended December 31, |        
|                                                                                                                                                                                                                                                                                                        |  | 2004                    |         |   | 2003 |   |         | 2002 |  |   | 2001    |   |  | 2000 |        
|                                                                                                                                                                                                                                                                                                        |  | (dollars in thousands)  |        
|Earnings:                                                                                                                                                                                                                                                                                               |  |                         |         |   |      |   |         |      |  |   |         |   |  |      |         |   |  |   |         |  
|Add:                                                                                                                                                                                                                                                                                                    |  |                         |         |   |      |   |         |      |  |   |         |   |  |      |         |   |  |   |         |  
|Income before minority interests in property partnerships, income from unconsolidated joint ventures, gains (losses) on sales of real estate
and other assets and land held for development, discontinued operations, cumulative effect of a change in accounting principle and preferred distributions |  | $                       | 309,124 |   |      | $ | 295,453 |      |  | $ | 271,713 |   |  | $    | 239,498 |   |  | $ | 204,538 |  
|Gains (losses) on sales of real estate and land held for development                                                                                                                                                                                                                                    |  |                         | 9,822   |   |      |   | 70,627  |      |  |   | 233,304 |   |  |      | 11,238  |   |  |   | (313    | )
|Amortization of interest capitalized                                                                                                                                                                                                                                                                    |  |                         | 2,845   |   |      |   | 2,640   |      |  |   | 2,526   |   |  |      | 950     |   |  |   | 415     |  
|Distributions from unconsolidated joint ventures                                                                                                                                                                                                                                                        |  |                         | 6,663   |   |      |   | 8,412   |      |  |   | 8,692   |   |  |      | 2,735   |   |  |   | 1,848   |  
|Combined fixed charges and preferred distributions (see below)                                                                                                                                                                                                                                          |  |                         | 334,082 |   |      |   | 342,244 |      |  |   | 316,835 |   |  |      | 306,709 |   |  |   | 275,607 |  
|Subtract:                                                                                                                                                                                                                                                                                               |  |                         |         |   |      |   |         |      |  |   |         |   |  |      |         |   |  |   |         |  
|Interest capitalized                                                                                                                                                                                                                                                                                    |  |                         | (10,849 | ) |      |   | (19,200 | )    |  |   | (22,510 | ) |  |      | (59,292 | ) |  |   | (37,713 | )
|Preferred distributions                                                                                                                                                                                                                                                                                 |  |                         | (17,063 | ) |      |   | (23,608 | )    |  |   | (31,258 | ) |  |      | (36,026 | ) |  |   | (32,994 | )
|                                                                                                                                                                                                                                                                                                        |  |                         |         |   |      |   |         |      |  |   |         |   |  |      |         |   |  |   |         |  
|Total earnings                                                                                                                                                                                                                                                                                          |  | $                       | 634,624 |   |      | $ | 676,568 |      |  | $ | 779,302 |   |  | $    | 465,812 |   |  | $ | 411,388 |  
|                                                                                                                                                                                                                                                                                                        |  |                         |         |   |      |   |         |      |  |   |         |   |  |      |         |   |  |   |         |  
|Combined fixed charges and preferred distributions:                                                                                                                                                                                                                                                     |  |                         |         |   |      |   |         |      |  |   |         |   |  |      |         |   |  |   |         |  
|Interest expensed                                                                                                                                                                                                                                                                                       |  | $                       | 306,170 |   |      | $ | 299,436 |      |  | $ | 263,067 |   |  | $    | 211,391 |   |  | $ | 204,900 |  
|Interest capitalized                                                                                                                                                                                                                                                                                    |  |                         | 10,849  |   |      |   | 19,200  |      |  |   | 22,510  |   |  |      | 59,292  |   |  |   | 37,713  |  
|Preferred distributions                                                                                                                                                                                                                                                                                 |  |                         | 17,063  |   |      |   | 23,608  |      |  |   | 31,258  |   |  |      | 36,026  |   |  |   | 32,994  |  
|                                                                                                                                                                                                                                                                                                        |  |                         |         |   |      |   |         |      |  |   |         |   |  |      |         |   |  |   |         |  
|Total combined fixed charges and preferred distributions                                                                                                                                                                                                                                                |  | $                       | 334,082 |   |      | $ | 342,244 |      |  | $ | 316,835 |   |  | $    | 306,709 |   |  | $ | 275,607 |  
|                                                                                                                                                                                                                                                                                                        |  |                         |         |   |      |   |         |      |  |   |         |   |  |      |         |   |  |   |         |  
|Ratio of earnings to combined fixed charges and preferred distributions                                                                                                                                                                                                                                 |  |                         | 1.90    |   |      |   | 1.98    |      |  |   | 2.46    |   |  |      | 1.52    |   |  |   | 1.49    |  
|                                                                                                                                                                                                                                                                                                        |  |                         |         |   |      |   |         |      |  |   |         |   |  |      |         |   |  |   |         |  



The ratio of earnings
to combined fixed charges and preferred distributions was computed by dividing earnings by combined fixed charges and preferred distributions. Earnings consist of income before minority interests in property partnerships, income from unconsolidated
joint ventures, discontinued operations, cumulative effect of a change in accounting principle and preferred distributions, plus amortization of interest capitalized, distributions from unconsolidated joint ventures, and combined fixed charges and
preferred distributions, minus interest capitalized and preferred distributions. Combined fixed charges and preferred distributions consist of interest expensed, which includes credit enhancement fees and amortization of loan costs, interest
capitalized, and preferred distributions.