Developer U3 Ventures plans to restore a three-story building at 40th and Ludlow Streets designed in the 1870s by architect Frank Furness that's been hidden for decades behind metal panels affixed to its facade.

U3 plans to spend as much as $5 million to renovate the historic building at 22 S. 40th St., which was built to serve as one of Philadelphia's neighborhood "institutes" that were precursors to the city's free libraries, company president Tom Lussenhop said.

U3 purchased the 15,000-square-foot building for $2.5 million last year from the Elwyn organization, a social service provider. Other past users have included the Philadelphia Electric Power Co.

The developer has begun seeking office and retail tenants to occupy the building after the completion of renovations, which are scheduled to begin in July and take less than a year.

Other works by Furness include the Pennsylvania Academy of Fine Arts building on North Broad Street, which was designed with fellow architect George Hewitt, and the Girard Trust Bank building, now the Ritz-Carlton hotel, on South Broad.