the Grand Canyon Skywalk is a large, semicircular bridge with a transparent glass floor, allowing tourists to walk out 70 feet from the canyon rim and view the bottom from 4,000 feet above.

An Aerial view of Jinmao Tower's open-air glass skywalk. Credit: Bu bian/Imaginechina/ap For safety precautions, only a maximum of 15 people are allowed on the skywalk at one time. Management also ...