U.S. Steel Tower, also known as the Steel Building (formerly USX Tower) is a 64-story, 256.34 m skyscraper with 2,300,000 sq ft of leasable space at 600 Grant Street in downtown Pittsburgh, Pennsylvania. It is the tallest skyscraper in Pittsburgh, the fourth tallest building in Pennsylvania, the 41st tallest in the United States, and the 187th tallest building in the world. It held its opening dedication on September 30, 1971. The tower's original name when completed was the U.S. Steel Building and was changed to USX Tower in 1988.