Cooper-Hewitt House, Gramercy Park, June 1925. In 1848, Peter Cooper left his longtime residence at Fourth Avenue and 28th Street (then a busy industrial area and slaughterhouse district), for a new mansion in the Gramercy Park neighborhood. Cooper shared his 35-room residence with his extended family, including son-in-law and future Mayor of New York City Abram Hewitt. Hewitt had befriended Cooper’s son Edward Cooper — himself the city’s 83rd Mayor — while traveling abroad in Europe. The Cooper-Hewitt bond was cemented when both me survived the capsizing of their return ship off of Cape May. Hewitt would go on to marry Edward’s sister, Sarah Cooper. Hewitt’s family continued to reside at 9 Lexington Avenue after Peter Cooper’s 1883 death, and even enlisted Gramercy Park neighbor Stanford White to design updates to the structure. The building was eventually replaced by a 13-story apartment building, completed in 1951.