New Development Plans Unveiled at Assembly Row

By Seth Daniel

As several developments in Assembly Row are now up and running, and others have just completed their steel skeletons, all of which are quite visible from Charlestown and of great concern here due to unresolved transportation plans, developers for the Row this week announced plans to proceed on a 1.9 million sq. ft. mixed-use development at Middlesex Avenue just beyond the Charlestown line.

According to, this week developers for Assembly Row released plans that would build out, in four phases, a 1.9 million sq. ft. development on 9.4 acres next to the Home Depot – in what is now largely just surface parking lots. The developer’s plans indicate they plan to build out a hotel, lab space, office space, more residential units and supporting retail. An office building already on the 9.4 acre parcel, which totals 195,000 sq. ft., would remain as part of the finished project.

The project, which bears an address of 5 Middlesex Ave. – the parcel closest to Charlestown, will begin with Phase 1 construction of a five-story mixed-use building which will house a combination of 147 hotel rooms and 147 residential living units. There will be retail on the ground levels and a publicly-accessible open space in a courtyard format. That phase would include an underground parking garage for 233 vehicles.

The other phases would include:

  • Phase 2: The largest of the buildings would take place in the second phase, with a 20-story tower containing 14 stories and 480,000 square feet of Class A office/lab space above a six-story podium. The six-stories would contain a mixture of 541 parking spaces on four floors and two levels of retail on the ground and second floors of the tower.
  • Phase 3: The bulk of the plans for the new development would come in Phase 3, with two, twin 19-foot towers being built side-by-side and connected by a link. They would sit above ground-level retail and above-ground parking. Together, the two linked towers would make up 1 million sq. ft. of premium office space.
  • Phase 4: Five-story mixed-use building containing 72 residential units, 16,000 square feet of retail and a 100-car parking garage.

There were no timelines given for the start of 5 Middlesex, and the phases had no attached date for their implementation either.

At the same time as that announcement came, two milestones were celebrated last week on buildings that are currently under construction.

The Alloy at Assembly Row is nearing its 13-story maximum height and will soon have a topping off ceremony when the final bits of steel are put in place on the top floor. That building will feature 122 condominiums that are expected to hit the market in early 2018. The condo units are on floors six through 13, and below them is a planned 159-room Marriott signature boutique hotel. There is slated to be 21,000 sq. ft. of ground-level retail reserved only for the first floor.

Next door to Alloy, the Block 6 building on Assembly Row has celebrated its topping off – hitting its 20-story maximum last week. reported from the developer that concrete has been poured on almost all levels and exterior finish panels are now being installed over the tower’s steel frame. Behind Block 6, a new parking garage to serve the overall area has now been completed as well.

Building 6 is expected to hit the market in January 2018, and that building is reserved mostly for residential uses – with 447 units to be delivered to the housing market with a complimentary 40,000 sq. ft. of retail on the ground floor.

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