What is the Gulf Tower in downtown Pittsburgh?

PITTSBURGH — You probably know what the Gulf Tower in downtown Pittsburgh is without knowing its name.

The iconic part of Pittsburgh’s skyline -- completed in 1932 -- features a light at the top that changes colors based on the weather forecast.

The light went dark in 1974 and returned in 1990, before being upgraded again in 2012.

Gulf Tower Gulf Tower

Gulf Tower The Gulf Oil Corporation building in Pittsburgh, Jan. 13, 1976. (AP Photo) (ASSOCIATED PRESS)

FREEMARKETS The full moon shines over a portion of Pittsburgh's skyline where the city's Gulf Tower at left is illuminated beside the peak of the Koppers building on Wednesday, Oct. 11, 2000. (AP Photo/Keith Srakocic) (KEITH SRAKOCIC/ASSOCIATED PRESS)

Detroit Red Wings v Pittsburgh Penguins - Game Six The Pittsburgh skyline during game six of the 2008 NHL Stanley Cup Finals between the Detroit Red Wings and the Pittsburgh Penguins at Mellon Arena on June 4, 2008. (Photo by A. J. Messier/Getty Images) (Getty Images)

Pittsburgh Prepares For World Leaders And Demonstrators Downtown Pittsburgh as seen on September 22, 2009. (Photo by Win McNamee/Getty Images) (Win McNamee)

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Gulf Tower Gulf Tower in downtown Pittsburgh on Wednesday, June 26, 2019. (AP Photo/Gene J. Puskar) (Gene J. Puskar)

Gulf Tower A full moon is visible from PNC Park through clouds as it rises between some of the buildings in the skyline during a baseball game between the Pittsburgh Pirates and the Chicago Cubs, Tuesday, Sept. 1, 2020, in Pittsburgh. (AP Photo/Keith Srakocic) (Keith Srakocic)

St. Patrick's Day 2021 Downtown Pittsburgh skyline goes green for St. Patrick's Day 2021.

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Gulf Tower Downtown Pittsburgh on Nov. 26, 2020. (AP Photo/Gene J. Puskar) (Gene J. Puskar/AP)

Gulf Tower Gulf Tower

Once the headquarters for the Gulf Oil Company, the 44-story building was the tallest in Pittsburgh until the U.S. Steel Tower opened in 1971.

The signature feature of the tower is the top of the tower, which is modeled after the ancient Mausoleum of Halicarnassus in Turkey.

The lights on the building’s pyramid became an instant landmark and popular among Pittsburghers for their color-coded weather predictions using Gulf’s corporate colors of blue and orange. The company even printed out postcards to help Pittsburghers decode the lights.