LOOKING DOWN

The Ledge is stationary, but your knees might wobble. These four glass boxes, in the Willis Tower (Chicago’s former Sears Tower), poke out from the 103rd floor, providing a unique and exhilarating viewing experience. Each box is made of clear glass -- three layers laminated together, for strength. The Ledge is included in the $14.95 price of a ticket to the tower’s viewing deck. Lines vary, and half-hour waits and longer are common. But time on the top is unlimited, and even the elevator ride is fun.

-- Richard Derk