Initially the caves were thought to be natural underwater reservoirs, but it soon became clear that humans had done this work. After 17 days of pumping it was obvious he had stumbled upon something pretty mega. These weren’t just roughly chopped hovels, there were gentle curves, sharp corners, finely crafted stairways. This was impressive handiwork.

The floor space of the first cave to be discovered is around 2,000 square metres and at its highest the cavernous room reaches 30 metres. Wu was rightly amazed by his find and started pumping out water from other nearby sources. He found another four caves similar in size to the first.

There is now believed to be 24 caves in the vicinity in total. According to some dodgy maths and guess-work, some have worked out that it would take 1000 people six years to carve out these caverns. (I never pay much attention to those sorts of estimates though, after all they don’t know who did it and how). However long it took them, suffice to say, they’re big.

All of the Longyou Grotto caves that have been inspected bear a similar chiseling method. Archaeologists think that this similarity might be significant. Pottery in the region, dated to between 500 and 800 BC also show similar patterns, so that could be a clue to their date.

☛ Up Next: The Mysterious “Band Of Holes” In Peru