Step out onto The Ledge, glass balconies that extend more than four feet outside of Willis Tower. Chicago is literally at your feet, 1,353 feet below. Watch the trains, expressways and river traffic from 103 floors above the Loop. Print out a kids' scavenger hunt from the website and see whether your family can spot Lincoln Park Zoo, Wrigley Field and other landmarks. "Knee-High Chicago" exhibits are also geared toward kids. The elevators travel at 1,600 feet per minute, so chew gum to help your ears pop.