The now-popular Grand Canyon destination The Skywalk solves some of the problems in structural designs since Galileo's time. The project is a good demonstration of the structural challenges that Galileo encountered especially the cantilever concept. Las Vegas-based entrepreneur David Jin was the investor of the project and consulted the architectural firm MRJ Architects and Lochsa Engineering as well as construction firm Apco Construction. Located at the Eagle Point on the western rim of the canyon, The Skywalk has a three layer glass walkway 3 inches deep wherein the top layer is replaceable when cracks and scratches happen. Visitors are given shoe covers so as not to slip or scratch the glass that much. The structure passed engineering requirements by 400% or a factor of safety of 4. The 65-foot-long cantilever is six-foot-deep and was opened in March 28,2007. Only 120 people are allowed at a time. The structure weighs 500 tons and is said to be the tallest man-made destination in the world.