Astronaut Buzz Aldrin and other VIP guests make the ceremonial first steps on the Skywalk at Grand Canyon West on the Hualapai Indian Reservation in Arizona on March 20, 2007. The USD 30 million glass-bottomed walkway juts out 70 feet from the rim at an elevation of 4000 feet above the Colorado River. Robyn Beck/AFP/Getty Images/TNS
A UNESCO World Heritage Site is selected for places that possess outstanding universal value for humanity in terms or cultural, historical, scientific or natural significance. They are also designated for protection and preservation under international treaties.
