Brandywine Realty Trust, Philadelphia's biggest office landlord, has bought almost the entire Center City block that was the site of 2013's deadly building collapse that flattened a Salvation Army thrift store.

The publicly traded investment trust bought the 37,000 square feet of land along the southern side of Market Street's 2100 block on Tuesday, president and CEO Jerry Sweeney said. He would not disclose the price.

The purchase of the site - including two buildings, a parking lot, a parking structure, and a vacant lot - is seen as a vital piece in linking Philadelphia's core office district to University City. It also nudges Brandywine further ahead as the city's dominant property owner.

The company already has 6.5 million square feet of office space, far more than the city's next biggest landlord, Equity Commonwealth, according to data provided by Jones Lang LaSalle, a commercial real estate services firm.

"We think it will be a good development site, as market conditions permit," Sweeney said. "Our immediate plan is to clean up the site, make it much more presentable."

Previous efforts to develop the block by Richard Basciano, who sold the land to Brandywine, ended with the death of six people when a building undergoing demolition collapsed onto the thrift shop on June 5, 2013.

The site of the collapsed building is now a lot that is included among 30,000 square feet of vacant space and parking that Brandywine will develop, though Sweeney said the company has not decided what it would build.

Also included are two three-story buildings that it will renovate into rental lofts, shops, and offices.

The purchase excludes the site of a memorial park to the victims at the western end of the block, where the thrift shop once stood, a fire station, and a third multi-story building that Basciano did not own.

While development has been pushing west from City Hall, the block has formed a virtual barrier for further growth on Market Street, said Craig Schelter, director of the Development Workshop, a trade group for the development community.

"Until that block gets done, you can't leap more to the west," he said.

Brandywine already has a significant presence on both sides of its newly acquired site. To the east are its twin Commerce Square high-rises and its 1900 Market Street building, which is being renovated. Near 30th Street station to the west are the mirrored Cira Centre building and the FMC Corp. skyscraper, now under construction.

The purchase follows Brandywine's acquisition this year of a parking structure on east Market Street, which is being heavily redeveloped.

"It just continues that roll-out of controlling key sites in the city, along a main corridor where there are very few good development sites available," said Mitch Marcus, a managing director at Jones Lang LaSalle.

215-854-2615 @jacobadelman