THE SKY'S THE LIMIT reveals the apartment-swapping adventures of many celebrities - from Jerry Seinfeld to Barbra Streisand, from Tommy Hilfiger to Gloria Vanderbilt - whose adventures in promiscuous apartment swapping and renovating are told with typical Gaines verve and style. And Gaines digs much deeper to tell us the fascinating story of how boxes stacked on boxes came to be seen as the ultimate in status for the rich. He explores the development of the cooperative apartment, originally conceived as a way to house the poor. He introduces us to a fascinating, diverse cast of carriage trade brokers, whose most important task is to get their anxious clients past the dreaded co-op board. And he gives us finely etched portraits of a few of the discreet, elderly society ladies who are the real arbiters of who gets into the so-called Good Buildings.