The Zeckendorf Towers, sometimes also called One Irving Place and One Union Square East, is a 345 ft-tall (105 m), 29-story, four-towered condominium complex on the eastern side of Union Square, Manhattan, in New York City. Completed in 1987, the building is located on the former site of the bargain-priced department store S. Klein. Designed by architectural firm Davis, Brody & Associates, and named in honor of prominent American real estate developer William Zeckendorf, it was one of New York City's most important development projects of the 1980s.

Union Square is a historic intersection and surrounding neighborhood in Manhattan, New York City, United States, located where Broadway and the former Bowery Road – now Fourth Avenue – came together in the early 19th century. Its name denotes that "here was the union of the two principal thoroughfares of the island". The current Union Square Park is bounded by 14th Street on the south, 17th Street on the north, and Union Square West and Union Square East to the west and east respectively. 17th Street links together Broadway and Park Avenue South on the north end of the park, while Union Square East connects Park Avenue South to Fourth Avenue and the continuation of Broadway on the park's south side. The park is maintained by the New York City Department of Parks and Recreation.