U. S. Steel is actually moving out of this tower to a new building to be constructed in its shadow, where the Civic Arena used to be. But this will always be the building that says “steel” on the skyline, or (depending on your opinion of the architecture) the building that says 2001: A Space Odyssey. When it opened in 1971, it was the tallest building outside New York and Chicago. Though there are many taller buildings now, it is still record-breakingly massive. There is no other building with a roof that big that high. All taller skyscrapers are narrower at the top; the U. S. Steel Tower is an acre on each floor and an acre on the roof. There is a good bit more office space in here than in the Empire State Building.
The architects were Harrison & Abramowitz, who also gave us the noticeably similar Westinghouse Building (now called 11 Stanwix) and the Alcoa Building (Regional Enterprise Tower for a while, but seems to be called something else now).