Willis Tower (formerly Sears Tower) was a large skyscraper located in Chicago. It had a height of 527 meters (1729 ft). It was completed in 1974, becoming it the tallest building in the United States, until the near completion of the Freedom Tower (1776 ft/541 meters) in New York of 2012.
During the 2012 apocalypse, Chicago was hit by massive earthquakes, which destroyed the buildings around the city and when Yellowstone Caldera Eruption (2012) occurred, the Yellowstone ash cloud devoured and caused the Willis Tower to be engulfed, killing the people inside of the building. During the Worldwide Flooding, the remains of the Willis Tower were swept away like the rest of Chicago by a gigantic tsunami at the height of 1500 meters.
When the apocalypse ended, the Willis Tower is submerged underwater along with the rest of Chicago and the United States.