7. The Willis Tower Sky Deck
Originally called the Sears Tower, it took 3 years to build and was opened to the public in 1974. It is a 110-story-tall building and was the world’s tallest office building until 1996, when the Petronas Twin Towers were built in Kuala Lumpur. The Willis Tower is 1,453 feet tall, and from a part which juts out from the Skydeck, called the Lounge, it is possible to see all of Chicago and up to 50 miles on a clear day.
