Willis Tower has an observation deck . It is called the Skydeck. It opened on June 22, 1974. It is on the 103rd floor of the building. It is 1,353 feet (412 meters) high. It is one of the most famous tourist attractions in Chicago. The observation deck is the highest public viewing area in the United States.  Tourists on the Skydeck can feel the building moving on windy days.  They can see the plains of Illinois and across Lake Michigan . Elevators take tourists to the top in about 60 seconds. People on the elevator can feel air pressure changes during the ride.