520 Park Avenue holds 35 residences within a 64 story limestone condominium tower. It was designed by Robert A.M. Stern Architects and developed by Zeckendorf Development. The tower is located at 60th Street between Park and Madison Avenue. 56 Leonard's 17,000 square feet of facilities include a 75 ' infinity swimming pool, indoor / outdoor cinemas, outdoor sundeck, gym, therapy facilities, steam room, sauna, lounge and a playroom for children. One of the Penthouses was sold for about $68 million dollars.