A group of tourists won't soon forget it, but a glass pane that shattered beneath them on a ledge atop Chicago's Willis Tower, the nation's second-tallest structure, posed no structural damage to the all-glass attraction, according to its fabricator and installer.
Designed "to prevent structural glass beneath it from being scratched, [the pane] allows visitors to walk out on the ledge in shoes rather than booties," says Mike Swanberg, president of MTH Industries, which also performs maintenance on the Skydeck on Willis' 103rd floor. The bay with the cracks is one of four that project 4.3 ft from the deck.