Somerville outlines a plan to expand Assembly Square

It’s focused on the long term development of about 140 acres between I-93 and the Mystic River

An artist's rendering of Somerville's updated Assembly Square Neighborhood plan.City of Somerville

Planners in Somerville on Wednesday took the wraps off a new vision for one of the prime spots where their city has room to grow: Assembly Square.

The city unveiled a neighborhood plan for about 140 acres between Interstate 93 and the Mystic River, a spot that includes the recently-built Assembly Row complex but also the older swaths of big-box retail and light industrial space that still surround it. It calls for roughly one-third of the area to be built out as housing, one-third as office and other commercial space, and one-third as open space, with taller buildings along both the highway and the river, and mid-rise development in between.

The plan — which was shared at a neighborhood meeting Wednesday night and will likely go before the city’s Planning Board for approval later this year — is more of an outline than hard-and-fast rules for what will go where. And it will likely take years, if not decades, to come to fruition. But it’s the first such plan for the area since the early 2000s — when Somerville envisioned a massive IKEA store along the Mystic — and signals a future neighborhood that will be far more urban and walkable than the suburban-style shopping centers that still cover much of the eastern edge of Massachusetts’ most densely-populated city.

“The new Assembly Square neighborhood plan is set to lead the way on sustainable, walkable, bikeable urban development,” said Somerville Mayor Joe Curtatone, in a statement. “[It] is designed to meet both our big goals like greenhouse gas reduction, housing, and economic growth, and our goals for improving daily life like more green space, healthy mobility options, and civic spaces that build community.”

The planning process began in Nov. 2020 with a series of virtual public meetings that attracted input from many people who live and work in the quickly-developing Assembly Row neighborhood, city officials said. It outlines five main goals — or “big ideas” — that include better connecting the area to the rest of Somerville, improving walkability and transit access, environmental sustainability, and boosting the city’s tax base. It also carves the area into four distinct districts — along with the already built-out Assembly Row complex — each with their own look and feel, from small-scale buildings in what’s now an industrial corner where Somerville borders Charlestown to a “research corridor” lining Middlesex Ave along I-93.

Much of that property is owned by a handful of large landowners. Assembly Row developer Federal Realty Investment Trust, for instance, owns the strip of big-box stores known as Assembly Marketplace. Those big players took part in the planning process and, in some cases, have already filed proposals that are before the city. Other sites, such as the 12 acres occupied by a very busy Home Depot on Mystic Avenue, are likely longer-term redevelopment opportunities, city officials said.

Of course, as Curtatone noted, Assembly has been a long-term redevelopment play for decades, really ever since the auto plant that gave the area its name closed in the 1950s. That eventually gave way to the now-shuttered Assembly Square Mall, and the vast mixed-use complex now under construction on part of the area.

“I’m so proud of the vision and the tenacity of this community,” he said. “Years ago, we could have settled for big box stores in a sea of parking, but with Assembly Row we instead created jobs, housing, transit, and water access, and a whole neighborhood.”

And now there’s a plan to make that new neighborhood even larger.