Answer: Bridge

Deep in the forests of Guangxi Province in China, there is a beautiful natural structure that, until recently, was entirely unknown outside of China as few Westerners had ever seen it: a massive limestone karst arch, known as the Xianren Qiao (Fairy Bridge), that spans the Buliu River.

In 2009 Jay Wilbur, a member of the Natural Arch and Bridge Society (NABS), came across the formation while looking over the aforementioned region of China in Google Earth. The discovery of an arch of such proportions caused quite a stir among NABS members and an expedition was sent to China in 2010 to formally observe and measure the arch. And when we say expedition, we certainly mean it. Not only does seeing the bridge require traveling to China, then into the remote region of an interior province, but just getting to the arch itself requires a three hour white water rafting trip on the Buliu River.

The trip was more than worth it, however, as their measurements confirmed that the Fairy Bridge wasn’t just a large natural arch, but the largest known natural arch by a nice margin. The arch clocks in at a lengthy 400 feet (121.9 meters) +/-15 feet (+/-4.57 meters) across, 60 feet (18.3 meters) longer than the next largest natural arch (the Zhijin Natural Bridge found in Guizhou Provice, China).