The Chicago Tribune just published a retrospective of Sears Tower's topping out on May 3, 1973, including many rare photos of construction.
Building Goliath: the making of the Sears Tower
"Willis Tower, formerly known as the Sears Tower, opened in 1973, though construction was not completed until 1974. The skyscraper was the world’s tallest building until 1998, when it was surpassed by a building in Malaysia. The 110-story tower has seen many changes in residents over the years, and in 2009 a new glass ledge was introduced on the building's 103rd floor."
Here are a couple of photos from the article (Credit: Charles Osgood and John Bartley)
The Tower Bums sing "She's the Tallest Rock" during the topping out ceremony.
Steelworkers raise the final white beam with over 12,000 signatures into place.