Thought of as “bottomless,” -- this was the notion for many years towards the ponds of Longyou County. Then a local valiantly set out to see how deep they really were, and discovered the first among many massive hand-carved caves. Its origin is almost a total mystery.

Back in 1992 in the Chinese village of Longyou, a curious local named Wu Anai, pooled his money together with his neighbors to purchase a water pump. Afterwhich, he began siphoning out the water in the pond in the village. The pond was among many in the area that were used for washing, fishing, and some other chores, and considered to be endlessly deep. Anai drained the entirety of one pond and found out that it wasn’t a pond at all, but instead, a flooded entrance to an ancient, man-made cave.

Soon, all 24 ponds in the area were also drained and they too were discovered to be the same strangely massive, hand-carved caves. The large caverns sink as deep as roughly 100 feet and sprawls out at the bottom. Although none of the caves are connected, some share thin walls, which remarkably was not punctured by the primitive builders. The cave walls are also bestrewn in carved lines and symbols that remains to be deciphered yet --- and that’s hardly the only enigma.

Although dated back as far as 200 BCE, these caverns have no historical record; neither their construction, nor any evidence of the materials used to build them, or even their purpose. Furthermore, no one is quite sure where the unearthed rock went, and these caves were too big to be accomplished by a small group of villagers. It would have taken about a thousand workers to build them in their day.

Despite the origin being unknown, the caves are now open to public visitors who are willing to make the trek towards the remote village.

H/T Ancient Origins