The Regional Enterprise Tower is a 410-foot-tall (120 m) skyscraper in Downtown Pittsburgh, Pennsylvania, formerly known as the Alcoa Building. It was completed in 1953 and has 30 floors. It is the 15th tallest building in the city and is adjacent to Mellon Square. A unique radiant heating and cooling system is contained in the ceiling: since there are no pipes, radiators, or air conditioning units along the exterior walls, an additional 15,000 square feet (1,400 m2) of rentable space was gained. Also, the windows rotate 360 degrees so they can be washed from the inside.