The Grolier Building, formerly 575 Lexington Avenue, is a commercial office building in midtown New York. Built in 1958, the building was in need of renovation as the aluminum curtain wall was aged for the 1990's real estate demands. The building underwent a re-clad with a then-new "high-performance, energy-conserving, state-of-the-art curtain wall." Bronze-colored glass was installed into a large-scaled aluminum grid that was attached to the existing aluminum mullions. When the exterior was completely sealed, the existing interior windows were removed.