According to CoStar, there are 4 Class A buildings under construction that can accommodate users of 50,000 square feet or more. They are located in the Seaport and Back Bay and have combined number of 1,610,202 square feet.
| Building Address | Submarket Name | Number Of Stories | Rentable Building Area | Typical Floor Size | Max Floor Contiguous Space | Total Available Space (SF) |
| 888 Boylston | Back Bay | 17 | 425,000 | 25,000 | 26,170 | 89,173 |
| 100 Northern Ave | Seaport | 17 | 395,202 | 23,247 | 32,006 | 154,931 |
| 140 Northern Ave | Seaport | 13 | 375,000 | 30,769 | 28,846 | 374,998 |
| 121 Seaport Blvd | Seaport | 17 | 415,000 | 24,412 | 34,400 | 414,202 |
| Total | 1,610,202 |