Fairy Bridge, China

Xianren Bridge ("Fairy Bridge") is the world's largest natural arch by a wide margin. Carved of limestone karst, the formation bridges Buliu River in northern Guangxi Province, China. Because of its remote location, accessible only by a three-hour rafting trip, it was not discovered until recently and remains relatively obscure. An expedition in October 2010 by the Natural Arch and Bridge Society first measured the bridge's span and found it to be 400 ± 15 feet (121.9 ± 4.6 m) in length