One57, formerly known as Carnegie 57 and nicknamed "The Billionaire Building", is a 75-story (marketed as 90-story) supertall skyscraper at 157 West 57th Street between Sixth and Seventh Avenues in the Midtown neighborhood of Manhattan, New York City. Upon completion in 2014, it stood at 1,005 feet (306 m) tall, making it the tallest residential building in the city for a few months until the completion of 432 Park Avenue. The building has 92 condominium units on top of a new Park Hyatt Hotel with 210 rooms, which is set to become the flagship Hyatt property.
The building's developer is Extell Development Company, the contractor is Lend Lease Project Management & Construction, and the architect is Christian de Portzamparc.  As of January 2015, it is home to the most expensive residence ever sold in New York City.