Observation platforms usually open up broad scenic vistas but seldom let you see what’s directly below. With new creations of laminated safety glass, however, that’s changing. The Skydeck of Chicago’s Willis Tower, formerly the Sears Tower,  has added four glass-bottomed balconies, nicknamed The Ledge, which let tourists peer down from the 103rd floor to neighboring rooftops  and streets. The wrap-around observation deck of China’s Oriental Pearl TV Tower similarly shows off views of downtown Shanghai and the Huangpu River, some nine hundred feet down.

More Skydeck views:

At the Grand Canyon, visitors can stroll out 70 feet beyond its western rim to gaze upon the Colorado River—some 4,000 feet below. The engineering marvel that makes this possible is the $30 million Skywalk, a cantilevered, horseshoe-shaped bridge with special 3-inch-thick glass floors. Secured by steel rods set nearly 50 feet into the canyon wall, the Skywalk was built to withstand an 8.0-magnitude earthquake, 100-mile-an-hour winds, and 71 million pounds of pressure.

The Grand Canyon Skywalk, via ariztravel/Flickr

Check out the New York Times photo feature, “Building with Glass.”

Other images via Skydeck Chicago at Willis Tower

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Tags: Architectural, Materials