Gulf's former headquarters, originally referred to as "the Gulf Building" (now the Gulf Tower office condos), is an Art Deco skyscraper. The tallest building in Pittsburgh until 1970, when it was eclipsed by the U.S. Steel Tower, it is capped by a "step pyramid" structure several stories high. Until 1973, the entire top was illuminated, changing color with changes in barometric pressure to provide a weather indicator that could be seen for many miles. After 1973 until the 2000s, only a beacon on top would change colors.