Longyou Caves, Ancient cave complex in Longyou County, China

The Longyou Caves are 24 artificial chambers cut into sandstone at Fenghuang Hill. Each averages over 1,000 square metres, with ceilings up to 30 metres high, and the total excavated area exceeds 30,000 square metres. Walls, ceilings and thick pillars share the same finish: parallel bands about 60 cm wide, filled with chisel marks set at roughly 60° to the band's axis.

In June 1992 four farmers from Shiyan Beicun drained five ponds, which proved to be man-made chambers; 19 more were found nearby. Clay from pots dated 206 BC–AD 23 was later recovered from silt inside. A 17th-century poem by Yu Xun mentions the caves, but no record explains their excavation.

The name of the complex comes from the county where farmers first uncovered the flooded chambers decades ago. Visitors today can see the parallel grooves on rock surfaces, showing traces of the tools and working methods used by those who excavated them.

The site opens in the morning and closes in the late afternoon, allowing enough time to visit several chambers. Walkways lead through the lit spaces, and sturdy shoes help on the sometimes uneven floors.

Individual chambers measure anywhere from 1,000 to 3,000 square meters, with each cave holding three or four massive columns that merge seamlessly into the ceiling. Despite the scale, no clues about their original purpose appear in any of the rooms, leaving questions that remain unanswered.