This article relies largely or entirely on a single source. (March 2020)
The Longyou Caves (Chinese: 龙游石窟), also called the Xiaonanhai Stone Chambers (Chinese: 小南海石室), 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 prefecture, Zhejiang province, China. Created more than 2,000 years ago, they were not recorded in any historical documents and were rediscovered by farmers in 1992.
In June 1992, four farmers in Longyou found the caves when they drained the water of five small ponds in their village. The ponds turned out to be five large manmade caverns. Further investigation revealed 19 more caverns nearby. They have been determined to be more than 2000 years old, and their construction is not recorded in any historical documents.
About 200km to the Northwest, the Huashan Grottoes at the riverbanks of the Xin'an River somewhat resemble the Longyou Caves, but have likely been built more than 1500 years later during the late Ming Dynasty (1552–1667 AD).
The caves are notable in several respects:
- The caves are very large considering their man-made origin: the average floor area of each cave is over 1,000 square metres (11,000 sq ft), with heights of up to 30 metres (98 ft), and the total area covered is in excess of 30,000 square metres (320,000 sq ft).
- The ceiling, wall and pillar surfaces are all finished in the same manner, as a series of parallel bands or courses about 60 cm wide containing parallel chiselling marks set at an angle of about 60° to the axis of the course.
- They have maintained their structural integrity and do not interconnect with each other.
- Li, L.H.; Yang, Z.F.; Yue, Z.Q.; Zhang, L.Q. (March 2009). "Engineering geological characteristics, failure modes and protective measures of Longyou rock caverns of 2000 years old". Tunnelling and Underground Space Technology. 24 (2): 190–207. doi:10.1016/j.tust.2008.08.003.
- Zhu, Cheng; Wu, Li; Zhu, Tongxin; Li, Feng; Zhang, Yun (May 2013). "Lichenometric dating and the nature of the excavation of the Huashan Grottoes, East China". Journal of Archaeological Science. 40 (5): 2485–2492. doi:10.1016/j.jas.2012.07.023.