Willis Tower is one of the most remarkable landmarks in Chicago. Formerly known asSears Tower, Willis Tower was the tallest building in the world from 1973 to 1998. Currently, it is the second tallest building in the United States. It surpassed One World Trade Center in 1973 to become the tallest building in the world while surpassed by Petronas Twin Towers (Malaysia) in 1998.
The Skydeck, is an observation deck at the 103rd floor of Willis Tower. It is one of the most popular tourist destination in Chicago and receives about 1.5 million tourist visitors annually. Indiana, Illinois, Michigan and Wisconsin can be viewed from the deck on a clear day.
The weight of the building is over 222,500 tonnes while there 1,500 hundred miles of electric wiring, 25 miles of plumbing and 145,000 light fixtures in the building.
The design of Willis Tower was inspired by an advertisement of a cigarette package. According to Bruce Graham (one of the architects of the building), he was holding his package of cigarettes during lunch and took inspiration for this building.
The elevators of the building just spend about 1 minute to take the tourists to the top floor.