Image courtesy of Elkus Manfredi Architects

The nation’s largest apartment developer chose Somerville for its entry into life science development, kicking off its first project in the emerging Assembly Square lab cluster.

Greystar’s 465,000-square-foot 74M tower in Assembly Square is the first development in its $1.2 billion joint venture with the Canada Pension Plan Investment Board that is planning a series of lab projects in Greater Boston and other U.S. life science clusters such as San Francisco, San Diego and Raleigh-Durham. Developers held a ceremonial groundbreaking next to the 74 Middlesex Ave. site Thursday, located between the Assembly Marketplace retail center and Interstate 93. Completion is scheduled for early 2024.

Gary Kerr, managing director for Greystar’s Northeast development services, said the partnership could expand to $2.5 billion worth of projects in key U.S. markets including additional sites in Greater Boston.

“We’re trying to be best in class and doing only ground-up development, not conversion. It’s really about quality and we want to be in the best markets,” Kerr said. “We don’t want to be in fringe markets. We want to be in places that are proven life science clusters.”

Assembly Square’s transit access and Somerville’s life science talent pool make the site attractive for a new lab project, Kerr said, in a neighborhood where developers including BioMed Realty and Federal Realty Investment Trust also are building and proposing life science buildings.

The 90-10 joint venture between the pension plan and Greystar is developing 74M as an all-equity project without a construction loan, Kerr said.

The site borders 96 Middlesex Ave., a 1.7-acre parcel which contains the former 99 Restaurant building, which Greystar also has under agreement. A formal development proposal will be submitted to the city of Somerville later this year, Kerr said.

“We’re still working through what that’s going to be with the neighborhood and figuring out what’s the right building for the site,” he said.

Designed by Elkus Manfredi Architects, the 15-story 74M tower will include a roof lounge and amenity terrace, conference and function rooms and ground-floor retail. The project includes a new neighborhood park on Kensington Avenue designed by Boston-based landscape architects Mikoung Kim Design, and a pedestrian and bike path connecting Assembly Row to the area west of Interstate 93.

JLL’s Pete Bekarian and Molly Heath lead the leasing team.

Greystar had more than 14,000 apartment units under development in 2021, according to the National Multifamily Housing Council, earning the top spot in its annual rankings.

Editor’s note: This story has been updated to correct the number of stories of 74M.