Construction began on April 17, 1961. The tower opened on April 21, 1962 for the 1962 World's Fair, called Century 21. It stands 605 feet tall to the top of the spire.
Edward E. Carlson's concept was a giant tethered balloon, sketched on a napkin. John Graham's concept was a flying saucer holding the restaurant and observation deck. Victor Steinbrueck added the hourglass profile and tripod design.
The revolving restaurant stopped turning on March 27, 1964, after the Alaska earthquake. A $100 million renovation reopened in August 2018, with a revolving glass floor called the Loupe.