Willis tower, formerly the Sears Tower, is a 110-story skyscraper, and this skyscraper is Chicago's most dominant structure and 2nd tallest building in the Western Hemisphere. On a clear day, one can see approximately 40-50 miles (65 - 80 kilometers), allowing one to easily see four states – Illinois, Indiana, Wisconsin, and Michigan. Skydeck has a ledge glass box extending 4.3 feet from the Skydeck, providing a clear view of 1,353 straight down.