Willis Tower
For 25 years, the tallest building in the world.
Key facts
- Completed 1973
- Formerly the Sears Tower
- 1,450 ft tall, 110 stories
- Tallest building in the world for 25 years
- "Bundled tube" design of nine square tubes
Narration transcript
Look to your right and up, way up, at the mighty Willis Tower, for many people the single most famous building in Chicago. When it was completed in 1973, and for the next twenty-five years, it was the tallest building in the entire world, soaring one thousand four hundred and fifty feet into the sky across one hundred and ten stories. For most of its life it was known by its original name, the Sears Tower, built for the giant Sears retail company. Its design was a brilliant new idea from engineer Fazlur Rahman Khan. Instead of one single tower, think of it as nine square tubes, all bundled tightly together like a fistful of square pencils held in your hand. Down at the bottom, all nine tubes rise together, but as the building climbs, the tubes stop at different heights and drop away, which is why the top has that distinctive stepped, notched silhouette. Bundling the tubes made it incredibly strong against the wind. Family tip: near the very top there is a famous glass balcony called the Ledge, where brave visitors step out onto a see-through floor with nothing but air beneath their feet, more than a thousand feet up.