Earlier this month, tenants began occupying architect Frank Gehry’s first residential supertower, which is New York City’s eighth-tallest high-rise structure and the tallest residential tower in the Western Hemisphere. The 76-story building, with its spectacular folded facade, is the first icon to appear on the lower Manhattan skyline since terrorists destroyed the 110-story towers of the World Trade Center. The $875-million building, although not completed, is on time and on budget, says the owner, Forest City Ratner Cos. The rental building’s signature is the undulating waves of stainless steel that reflect the changing light. The skyscraper, currently called New York by Gehry, was earlier known as Beekman Tower.