Project Details

One Union Square is a proposed mixed-use residential development at the heart of Union Square, Somerville — directly adjacent to the new Green Line T Station. 

The previously contemplated lab building for this site is no longer economically viable to develop. In response to Greater Boston's significant housing shortage, and the fact that millions of square feet of commercial space have already been permitted and built in Union Square since the passage of the Union Square zoning ordinance, The Hamilton Company is seeking a zoning map amendment from CC5 to MR6 to allow residential use on this site. 

The City of Somerville has confirmed that The Hamilton Company has the right to pursue development on this property.

The proposed project will deliver 150–200 residential units, ground-floor retail and civic uses, and meaningful public open space — all within a building that respects the neighborhood's scale and character. 

Project Metrics

The project will also provide relocation assistance for all existing businesses on the site, as well as generate a significant increase in property tax revenue over current uses, providing new resources for the City.

Comparison of current and proposed zoning metrics

Height Comparison Diagram

Shadow Study
March 21 / September 21

Community Benefits

One Union Square offers a comprehensive set of community benefits:

  • 150–200 new housing units (30–40 affordable)

  • A unit mix of over 50% two- and three-bedroom homes for families

  • At least 15% publicly accessible civic space and 25% at-grade open space

  • City-planned streetscape improvements for pedestrians and cyclists

  • The potential for a dedicated Somerville Public Library branch.

Approval Timeline

Where are we in the process?

The project is currently in the Zoning Map Change phase.

A zoning map amendment application has been submitted to the City of Somerville. The next public milestone is: 

City Council & Planning Board Public Hearing — April 16, 2026

Following zoning approval, the project will proceed through Special Permit and Site Plan approval before construction begins.