The iconic, decades-old Williams Tower in Houston’s Uptown has a new owner after an energy firm purchased it for more than $300 million.

Oklahoma-based Williams Companies, which transports about a third of the nation’s natural gas, closed on the 1.4-million-square-foot office tower on Monday. The company already has about 700 employees operating out of Williams Tower and another 100 working in downtown Houston.

Sitting next to the Galleria, the 64-story skyscraper helped transform Uptown into a major business district.

Here’s what to know about the historic building that defined Houston’s Uptown skyline:

The skyscraper first opened as Transco Tower in 1983. It was the tallest building in the world outside of a traditional downtown.

The late real estate developer Gerald D. Hines, who had already transformed downtown with towers such as One Shell Plaza and Pennzoil Place, operated much like the wildcatters who helped build Houston’s fortune. They gambled on underground oil reserves; he gambled on skyscrapers.

Transco Energy commissioned real estate developer Gerald D. Hines to build a skyscraper just west of Loop 610. Hines had previously designed other towers in the city, such as the One Shell Plaza and Pennzoil Place.

As oil prices plunged in the 1980s, many producers were forced into bankruptcy and energy companies had to merge with others, sell themselves or disappear altogether.

In 1995, Williams Companies acquired Transco Energy, and the Transco Tower was subsequently renamed Williams Tower.

During the daytime, Houstonians might see what appears to be a shadow of a cat extending down the corners of Williams Tower, created by the vertical lines on each face of the building.

It’s unclear whether the optical illusion was intentional. However, in the book “Secret Houston: A Guide to the Weird, Wonderful, and Obscure,” author William Dylan Powell wrote that building designer Philip Johnson loved cats and frequently incorporated them into his designs.

A Chron article also reported that Mark Clegg, vice president of corporate communications for Hines’ real estate firm said the cats visible on the building weren’t put there by accident.