The Grand Canyon Skywalk is a glass bridge suspended 4,000 feet above the Colorado River at the edge of the Grand Canyon. Construction began in 2004 and was completed in 2005, passing tests by withstanding over 71 million pounds, the weight of 71 fully loaded 747 airplanes. The bridge can withstand winds over 100 mph from all directions and an 8.0 magnitude earthquake within 50 miles, using over 1 million pounds of steel in its construction.