Some might be surprised to learn that The John J. Flatley Co. is headquartered in Massachusetts, given its prominence in Nashua.

The Braintree-based Flatley Co. is one of the city’s largest property owners. The company is developing hundreds of acres of land bordering the F.E. Everett Turnpike between Exits 1 and 2 into a mixed-use industrial park.

To boot, the company’s director of planning and development, Dick Cane, is a former planner for the city of Nashua.

The Flatley Co., founded in 1985, owns property throughout Massachusetts and New Hampshire.

The company owns and operates offices, research and development complexes, and apartment communities. Its commercial tenants in Nashua include major technology and health care firms such as Dell, Aspen Technology Inc., and United Healthcare.

Development along the turnpike in South Nashua has been in discussion since the Flatley Co. bought the former Digital Equipment Corp. buildings there in 2007. Hundreds of surrounding wooded acres were already owned by Flatley and had been for four decades. But the Digital piece connected the land, creating one giant parcel that lends itself to major development.

“This is the last major development piece in the city of Nashua,” said Cane, the planning and development director, when plans for the mixed-use development were unveiled in 2012.

Plans for the 400-acre site, dubbed Gateway Hills, include upscale apartments, retail, manufacturing facilities, medical offices, technology space, walking trails, a multipurpose field, vegetable gardens and a rebranded fitness center.

This year, the company opened a retail and medical complex on the site called Tara Commons, which consists of four single-story buildings. The first phase of an 180-unit apartment complex,

Tara Heights, opened earlier this year. The complex will include five three-story buildings spread over 21 acres with one- and two-bedroom units. In September, the company got approval to build a 6,400-square-foot restaurant/retail store on the site.

In a decade or so, Flatley hopes Gateway Hills will be home to more than a million square feet of research and industrial buildings plus 420 high-end apartments.

The Gateway Hills project was formerly called Nashua Technology Park, but it was rebranded to broaden the scope of the development beyond tech firms. However, some 700,000 square feet of office space on the site – where Digital was formerly located – is being called Nashua Technology Park at Gateway Hills.

When Flatley bought those former Digital buildings in 2007, they were 75 percent vacant. But they’ve since managed to lease some 400,000 square feet of space. Flatley has spent millions of dollars to improve the buildings, including new entrances, lobbies, elevators, hallways, a theater-style auditorium and a conference center, Cane said.

Earlier this year, the company was one of three finalists for the Greater Nashua Chamber of Commerce Business of the Year award.