The Woolworth Building is an early American skyscraper located at 233 Broadway in Manhattan, New York City. Designed by architect Cass Gilbert, it was the tallest building in the world from 1913 to 1930, with a height of 792 feet. It remains one of the 100 tallest buildings in the United States as well as one of the 30 tallest buildings in New York City. Its facade is mostly decorated with terracotta (though the lower portions are limestone) and contains thousands of windows. The ornate lobby contains various sculptures, mosaics, and architectural touches. The structure was also designed with several amenities and attractions, including a now-closed observatory on the 57th floor and a private swimming pool in the basement. The skyscraper was originally conceived by F. W. Woolworth, the founder of a brand of popular five-and-ten-cent stores, as a headquarters for his eponymous company. Woolworth planned the skyscraper jointly with the Irving National Exchange Bank, which also agreed to use the structure as its headquarters. The Woolworth Building had originally been planned as a 12- to 16-story commercial building, but underwent several revisions to its plans during its planning process. Its final height was not decided upon until January 1911. Construction started in 1910, and it was completed two years later. The building officially opened on April 24, 1913.