Project Progress: Under Official Review
About 5 Middlesex Avenue
The Office and Research Center + The Residences at Assembly
Assembly Row, Somerville, MA
Proposed four-phase, 1.9 million square foot development of a 9.4-acre Assembly Row parcel largely comprised of surface parking into a mixed-use complex with hotel, lab, office, residential and retail uses. An existing 195,000 square foot office building (Block 24) would be retained. The four phases would be constructed as follows:
- Phase 1 (Block 21): Five-story mixed-use building containing a 188-room hotel, 147 residential units and ground-floor retail facing public open space at the center of the site. Phase 1 would also construct 233 surface and subsurface parking spaces.
- Phase 2 (Block 22): 20-story tower containing 14 stories and 480,000 square feet of Class A office/lab space above a six-story podium. The podium would contain two levels and 31,000 square feet of retail underneath four parking levels with 541 spaces.
- Phase 3 (Block 23): Two 19-story, 1 million square foot office towers connected by a link. These towers would also sit above a retail and parking podium.
- Phase 4 (Block 25): Five-story mixed-use building containing 72 residential units, 16,000 square feet of retail and a 100-car parking garage
Below is a site plan showing the 5 Middlesex Avenue development plan. A rendering of the 5 Middlesex Avenue development can be found above.

Square Feet | 1,941,592 |
Sector |
Housing Hotel Parking Retail Office Restaurant Lab |
Stories | 250 |
Height (feet) | 20 |
Start Date | Dec 31, 2019 |
Latest Updates
Jan 15, 2018
Oct 16, 2016