A long-delayed development site is nearing the finish line in East Boston, just in time to join the neighborhood’s enhanced art scene and burgeoning multifamily construction boom.

Boston East, Trinity Financial’s 200-unit rental complex, is scheduled to open in September. Trinity is now accepting applications for six “live-work-sell” artist units that will be made available to households earning up to 70 percent of the area median income. The 6-story Border Street complex designed by Boston-based Icon Architecture will include a first-floor gallery showcasing local works.

Market-rate units will lease from $2,000 to $4,700, with an average rent of $2,900, said Abby Goldenfarb, a vice president for Trinity Financial. Artists’ units will rent for $1,450.

Shipbuilders, coal storage and a carriage factory once occupied the 7-acre property during the neighborhood’s industrial past, but the site sat vacant in recent decades through a series of boom-and-bust real estate cycles.

Trinity’s involvement stretches back to 2004, when the city’s Department of Neighborhood Development issued a request for proposals to develop the site. Originally, Trinity proposed the neighborhood’s first market-rate condominium development. After the recession, Trinity found a formula enabling it to make the $71 million project feasible in 2014. The final modifications reduced the building from seven to six stories, enabling wood-frame construction techniques, and shrunk the basement parking garage from 150 to 120 spaces.

The successful performance of Roseland Property Co.’s nearby Portside at East Pier apartment complex, which opened its first phase in 2014, set the stage for the neighborhood’s current development boom, Goldenfarb said.

“It really gave the investment community a lot of comfort,” she said. “There was a comp to look at for what they were getting in rents. As a bank or investor, you never want to be the first one in.”

Trinity Financial acquired the parcel from the city for $2 million in 2015. The project received a $3 million MassWorks infrastructure grant for an extension of the Boston Harborwalk.

Reflecting the emphasis on communal spaces in new developments from office buildings to hotels, Trinity Financial sacrificed potentially lucrative leasable space on the top floor in favor of an indoor-outdoor rooftop lounge.

“It seemingly could have been the best few units and we made it amenity space. Even if you’re not spending the most money, you have access to all of those views,” Goldenfarb said.

The property joins a growing art cluster along the East Boston waterfront including the Atlantic Works Gallery and East Boston Artist Group studios at 80 Border St. The Institute of Contemporary Art will arrive in the neighborhood next summer when it opens a satellite gallery at the Boston Harbor Shipyard and Marina.

Trinity Financial is working with the East Boston Art Assoc. to curate exhibits at Boston East’s public arts gallery. The six artists’ units are among 20 income-restricted residences in the development. Applications for artists certified by the Boston Planning and Development Agency are available at 31 Liverpool St., East Boston or by emailing BostonEastMgr@trinitymanagementcompany.com. The deadline is June 16.

East Boston Community Development Corp. is seeking marine industrial users for a section of the property that is a designated port area.