These luxurious living spaces became popular in Manhattan during the 1920s, when the booming economy fueled a skyscraper construction boom. In 1925, New York City legalized these exclusive top-floor units, and businessman Condé Montrose Nast and heiress Marjorie Merriweather Post were among the first owners. Prior to being rebranded as luxury residences, a penthouse referred to smaller servants' quarters that could be hidden from view on a building's roof.