The historic Stephen Girard Building in Philadelphia's Market East district is being transformed into a hotel under Hilton's boutique Canopy brand as part of the $800 million initiative to revamp the blocks that surround it.

Plans call for the 13-story, 120-plus-year-old Beaux Arts building on 12th Street, between Market and Chestnut Streets, to accommodate about 251 guest rooms, according to documents filed with the city in connection with the project's financing.

The hotel plan is part of the East Market commercial and residential complex that is set to eventually encompass the entire property bounded by Market and Chestnut Streets, between 11th and 12th Streets, which was once known as Girard Square. Washington-based National Real Estate Development controls the property under a long-term lease with its owner, the estate of late Philadelphia tycoon Stephen Girard.

Dan Killinger, the National Real Estate managing director overseeing the East Market project, declined through a spokesman to comment on the hotel plan. Messages seeking comment from McLean, Va.-based Hilton Worldwide Holdings Inc. yielded no response.

In a 2014 conference call with analysts, shortly after the Canopy brand was introduced, Hilton chief executive Chris Nassetta characterized the hotel line as "an accessible lifestyle brand" designed to "reflect the local neighborhood flavor and culture where each hotel is located."

The company has 27 Canopy properties operating or soon to open in cities including Dallas, Atlanta, Washington, London, and Chengdu, China. Its most recent opening was last month in Zagreb, Croatia, according to its website.

In addition to the hotel plan, National Real Estate plans to build space for a restaurant and two stores on the Stephen Girard Building's lower stories, according to Department of Licenses and Inspections records.

The developer is nearing completion of its plans for the Market Street-facing northern two-thirds of the property, where the Stephen Girard Building stands. It has developed within the section a pair of apartment towers and an office building, with lower-story spaces occupied by branches of Iron Hill Brewery & Restaurant, TJ Maxx, Mom's Organic Market, and Little Baby's Ice Cream.

It recently obtained a permit to demolish a parking garage on the southern, Chestnut Street-facing third of the block, where it plans two additional "mixed-use towers" atop retail spaces, according to its website.