are collectively dubbed Billionaires' Row by the media. Other buildings along Billionaires' Row include 432 Park Avenue, 111 West 57th Street, One57, and Central Park Tower on 57th Street, as well as 220 Central Park South on Central Park South (59th Street). Architecture Officially named 53 West 53, the building was designed by French architect Jean Nouvel as a 77-story, 145-unit tower. The building has 77 physical stories. The top story is numbered 87 and several floor numbers are skipped. There are also two basement levels; the cellar immediately below ground is used as storage by MoMA, while the subcellar beneath it contains mechanical rooms for the upper stories. The highest occupied story is above ground. The tower technically measures tall from the lobby floor to the tip of its tallest spire. This makes it the tenth-tallest completed building in the city . The site is split between three different zoning districts, each of which had different setback requirements. During planning, Nouvel's team designed a sloping structure to follow the setback requirements and various parcel restrictions on the site. The ultimate design for the building has five spires. Facade The building's facade is framed within a concrete diagrid, which shifts the tower's structural system to the exterior, thereby allowing more open space for the interior of each floor. The diagrid was designed by WSP Global, which spent over a year modifying the details of the design. Nouvel and the WSP engineers collaborated extensively on the superstructure's design because Nouvel wanted 53 West 53's facade to reflect the arrangement of the diagrid. The diagrid includes vertical, diagonal, and horizontal girders to carry weight loads while also stiffening the frame against wind. The design of the facade around the diagrid was inspired by drawings made by Hugh Ferriss. As designed, the north and south facades slope away from the street as they rise, while the west and east facades are perpendicular to ground level. The exterior curtain wall is made of 5,747 triple-glazed panels manufactured in Germany. The curtain wall consists of glass panes, aluminum frames, and ventilation grates. Mockups of the windows were tested in a wind tunnel before being installed. The curtain wall is anchored to the concrete floor slabs. Part of the lower stories' facade, and some portions of the west and east facades that abut other buildings, are made of masonry. Custom window blinds were required for the