The Longyou Caves are a mysterious set of underground caves located in the Zhejiang Province of China. Discovered in 1992, the caves are believed to have been carved out of soft rock by human hands over 2000 years ago. The caves are vast, with an estimated total length of
From Wikipedia
The Longyou Caves, also called the Xiaonanhai Stone Chambers, are a group of 24 artificial sandstone caverns located at Fenghuang Hill, near the village of Shiyan Beicun on the Qu River in Longyou County, Quzhou City, Zhejiang Province, China. It is unknown when the caves were created; they are mentioned in a 17th-century poem by the Yu Xun, and clay from pots dated to between 206BC and 23 AD were found in silt within the caves.