During his chairmanship for the Department of Architecture at Harvard University, Walter Gropius continued his professional practice. He later formed TAC, The Architects' Collaborative, in 1945. The highly criticized and praised Pan Am Building, with its unusual shape, is a familiar landmark at the soutern end of Manhattan's Park Avenue. The glass wrapped structure, which once featured the letters PAN AM boldly across the top, rises up conspicuously behind Grand Central Station to the south. (Adapted from A Field Guide to Landmarks of Modern Architecture in the United States, by Miriam F. Stimpson)