The Longyou Caves are a series of large artificial sandstone caverns located at Phoenix Hill, near the village of Shiyan Beicun on the Qu River in Longyou County, Quzhou prefecture, Zhejiang province, China. They are thought to date to a period before the creation of the Qin Dynasty in 221 BCE, although no trace of their construction or even their existence has been located in the historic record.
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 a 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 appear not to interconnect with each other.