Developer Brandywine Realty Trust is seeking to build a 23-story commercial and residential tower on the Market Street block that was the site of the 2013 deadly building collapse that flattened a Salvation Army thrift store.

The tower planned by Brandywine, which has owned most of the block bounded by 21st and 22nd Street between Market and Ludlow Street since 2015, would have 553,000 square feet of offices, dwellings and retail, the company’s chief executive, Jerry Sweeney, said this week.

The proposal calls for 326,000 square feet of office space and 147 residential units, with shopping and dining on the first and second floors, Sweeney said.

The company is seeking approvals for the building, to be designed by Philadelphia-based Erdy McHenry Architecture, but will not begin construction until an anchor tenant is secured for its office space, he said.

Maggie Mund, president of the Center City Residents Association, said her group supports Brandywine’s request for a change in the 2120 Market St. site’s zoning to permit the high-density project.

City Council’s Rules Committee is scheduled to vote next month on legislation to change the zoning to the city’s most permissive designation.

The bill also would designate the memorial to the June 5, 2013, accident on the block’s western edge as public space. The accident claimed the lives of six people when a building undergoing demolition collapsed onto the thrift shop.

The 0.7-acre development site for the proposed tower spans from the memorial to the fire station on the block’s eastern half. Brandywine cleared the parcel of an aged industrial building in 2016 and has since operated a parking lot at the property.

The land, along with two three-story buildings that Brandywine has since renovated at the block’s eastern end, were acquired for $16.6 million from property investor Richard Basciano. The properties were among a number sold by Basciano as he faced lawsuits over the building collapse.

Philadelphia-based developer Parkway Corp. said earlier this year that it wants to build an 18-story office building on land just a block to the west that it acquired around the same time from Basciano, who died in May 2017.