Perched 4,000 feet above the Colorado River on the very edge of the Grand Canyon is one of the most recent and innovative engineering marvels of our time. The Grand Canyon Skywalk, opened to the public in March 2007, is an engineering masterpiece united with natural wonder. It is the first ever cantilever designed glass bridge. Constructed in a horseshoe shape, visitors are given the chance to walk out over the edge of the canyon and look straight down. It's about 4,000 feet above the canyon, which is higher than any of the world's largest buildings and extends 70 feet from the edge. Take a closer look at the Skywalk's design, construction and the people that made it a reality. (thetvdb.com)