Alexandria Real Estate has quietly set a big shift in motion at 311 Arsenal Street in Watertown, filing permits to overhaul part of the former athenahealth headquarters so three biotech tenants can move in. The plan would inject fresh lab and research space into the Arsenal on the Charles campus and stands out as one of the clearest signals yet that landlords are hustling to backfill large suburban life‑science properties as leasing cools across parts of Greater Boston. The work zeroes in on the 311 Arsenal building, which has been circling through repositioning concepts for several years.
Permits Point To Biotech Tenant Fit‑Outs
According to the Boston Business Journal, Alexandria has submitted building permits to refit space at 311 Arsenal Street for three biotech companies. Public records reviewed by the outlet flag the applications as tenant fit‑outs meant to prep interior space for research and lab operations. These filings are the first public permitting activity this year that specifically ties new biotech occupants to the property.
What Alexandria Is Telling Investors
Alexandria's Q1 investor presentation and earnings materials list 311 Arsenal Street as part of the company’s Arsenal on the Charles megacampus and show the site being marketed for advanced‑technology and life‑science uses. The documents state that Alexandria has executed roughly 82,000 square feet of letters of intent with advanced‑technology tenants at the property and that construction milestones are scheduled later in 2026 as the firm gauges delivery timing. Taken together, the materials frame the strategy as a mix of repositioning and selective fit‑outs rather than a full teardown or complete redevelopment of the existing building.
How 311 Arsenal Landed In Alexandria’s Hands
The 311 Arsenal building served for years as athenahealth’s headquarters before Alexandria acquired it in 2019 for roughly $525.5 million, according to local real‑estate reporting. Since then, developers and analysts have been watching the suburban lab market closely amid softer leasing and rising availability. Alexandria has indicated it is weighing different tenant mixes and potential asset sales to balance capital needs, and coverage in the trade press notes the company has been marketing pieces of several megacampus properties to non‑traditional lab users as demand patterns shift.
Inside The Building: Lab‑Ready And Modular
Commercial listings for 311 Arsenal present the property as loaded with lab‑ready and research suites, marketed through JLL and other brokers, with multiple floorplates and turnkey lab features promoted as available now or later this year. Those marketing materials point to lab benches, tissue‑culture rooms, cold storage and other built‑in infrastructure designed to cut down the time required for tenants to move in once permits and fit‑outs are finished, according to the LoopNet listing. The listing language underscores that the building can transition into life‑science use in phases instead of undergoing a full reconstruction.
What It Could Mean For Watertown
If the current round of fit‑outs moves ahead and tenants ultimately take space, the project would bring additional lab and office jobs to the Arsenal on the Charles campus and help soak up some of the region’s available lab inventory. How quickly that plays out depends on permit approvals and construction schedules. For now, the permits and public documents do not spell out tenant names in detail, leaving local officials and nearby residents watching the permitting docket and brokerage listings for the next clue. At this point, the filings and Alexandria’s own investor materials are the clearest public indication that the former athenahealth building is actively being repositioned for biotech use.
