What is the world's largest natural arch?

Xianren Bridge also known as Fairy Bridge, is the world's largest natural arch with a span measuring 400 feet or 120 meter. The bridge is carved through the limestone karst by the Buliu River. It is located about 40 km northwest of Fengshan in northwestern Guangxi Province, China.

Until recently, Fairy Bridge has been virtually unknown outside of China. The Natural Arch and Bridge Society (NABS) first became aware of it in 2009 when a geologist was searching the area using Google Earth and spotted what looked like a large natural bridge spanning a river. This was quickly confirmed by a Panoramio photo linked to Google Earth, taken by the Chinese photographer. Estimates using Google Earth and other photos suggested that the span might be the largest in the world. After a failed attempt, the bridge was successfully reached and measured in 2010 by a NABS team.