Dating over 2,000 years ago, the Longyou Grottoes are some of the most mysterious and fascinating finds in China. Discovered in 1992 by a local Chinese villager, over 36 grottoes had been discovered covering a 30,000 square foot area. With man-made rooms, massive pillars, bridges, and pools, no one really knows how they were built so long ago and for what purpose. No known written history has been recorded about them.