Charles Sumner Greene and Henry Mather Greene were brothers who formed an important architectural firm which went on to design a number of notable residences, including the Blacker, Gamble, Pratt, and Thorsen houses. Their substantial collection of architectural drawings, photographs, personal papers, and other manuscript materials found their way into the Avery Architectural and Fine Arts Library at Columbia University. Visitors to the site can start their exploration of this fine material by looking over the indexes, which include listings by personal names, subject headings, geographic names, and genre/medium type. It's quite a bit of fun to browse through the image index, as visitors can view drawings and photographs of notable houses, churches, and office buildings executed by the Greene brothers.