Longyou Grottoes

The Longyou Grottoes, in Shiyan Beicun village of Longyou County under Quzhou's administration, comprise 24 large man-made caves carved from sandstone bedrock, discovered by local villagers only in 1992 when they pumped water from what had been assumed to be a natural pond for centuries. No historical documents, inscriptions, or artifacts recovered from the caves definitively date their excavation, though geological and tool-mark analysis suggests they were carved sometime before the Ming dynasty, with some researchers proposing an origin as early as the Warring States or Han period based on regional quarrying practices. Each cave features chiseled walls, ceilings, and support pillars cut with remarkably uniform parallel tool marks, and cave interiors reach heights of up to 30 meters, representing an estimated combined excavation volume of over 300,000 cubic meters of rock removed without any known written record of the labor or purpose behind it. Theories about the caves' original function range from ancient quarries supplying construction stone, to military storage or shipbuilding sites, to religious or burial complexes, but none has been conclusively proven, and the absence of any historical reference to caves of this scale in Chinese records remains a central mystery for regional archaeologists. Since their discovery, several caves have been pumped dry, lit, and opened to visitors, while others remain flooded and unexplored, and a small on-site exhibition presents the competing theories without endorsing any single explanation.