After graduating, Edward Harkness married Mary Stillman, daughter of wealthy New York attorney Thomas E. Stillman, in 1904. Mary's maternal grandfather was Thomas S. Greenman, a shipbuilder in Mystic, Connecticut, who co-founded George Greenman & Co shipyard. (This is now part of the Mystic Seaport Museum). Harkness' mother gave the couple a new Italian Renaissance mansion on the Upper East Side as a wedding present. As the building's architect, Harkness chose Yale College classmate James Gamble Rogers, who would later design many of his philanthropic building projects. The home, at 75th Street and 5th Avenue and now known as the Edward S. Harkness House, became the headquarters of Harkness' Commonwealth Fund after Mary's death.