740 Park Avenue is a cooperative apartment building between East 71st and 72nd Streets in the Lenox Hill neighborhood of the Upper East Side. Units in the limestone-clad building, erected in 1929, are some of the most expensive homes in the United States. Arthur Loomis Harmon and Rosario Candela designed the building for developer James T. Lee, Jacqueline Kennedy Onassis' grandfather. 740 Park Avenue was Jackie's home growing up. It has 31 units. The building is known for its high ceilings and wide hallways. Other residents have included the artist Saul Steinberg, Chrysler heiress Thelma Chrysler Foy, chemical engineering billionaire David H. Koch and cosmetics tycoon Ronald Lauder. Stephen Schwarzman, the founder of the private equity firm the Blackstone Group, bought his 34-room spread in 740 Park Avenue from Steinberg in 2000 for $35 million, a record price for a New York City co-op at the time. Other records followed. Howard Marks, who runs investment fund Oaktree Capital, and his wife, Nancy, bought a duplex from Courtney Sale Ross, the widow of Time Warner chief executive Steven J. Ross, in 2012 for $52.5 million. Israel Englander, a hedge fund manager and billionaire, purchased a unit in 2014 for $71.3 million.