The villages of Longyou County, in Zhejiang province, China, have long been renowned for their scatted ponds of extraordinary depth, which have become over the centuries wellsprings of myth and folklore and which are often collectively called the “Bottomless Ponds,” said to stretch infinitely down into the bowels of the earth. It was at one such pond that in 1992 a local farmer by the name of Wu Anai, from the village of Shiyan Beicun, got it into his head to see how true the legends were, and how deep the pond near his own village really was. To this end he went about gathering up a powerful water pump to actually begin emptying the pond. What he found in the “Bottomless Pond” would astound everyone who saw it, become known as the “‘the ninth wonder of the ancient world,” and launch an intriguing historical mystery that has never been solved.
As the water was laboriously siphoned out, a process that took days, it became apparent that this was no normal, naturally made pond, but rather an immense, underground cavern system that seemed to be manmade, carved right into the sandstone beneath them and inundated with water. The cave sprawled out beneath them was fully equipped with stone rooms, pillars, all decorated with cryptic lines and symbols that have been meticulously etched into the stone and with meanings unknown. This discovery soon had other nearby villages draining their own ponds, until over the years 36 similar grottoes were unearthed, all within an area of just one square kilometer. They penetrate down into the earth for 100 feet or more, each an average of 11,000 sq. ft. in area, and although not connected they are often separated only by very thin walls, and were obviously made by the same builders. Despite being examined by numerous experts and scientists, no one has any more understanding of them they did back when that first cave was discovered, and their mysteries are deep.
Perhaps the biggest mystery of what have come to be called the Longyou Caves is that no one really knows who built them, why, or how. They have been estimated as dating back to perhaps 200 BC, but there is absolutely no record of their construction in any of the historical records, nor even any reference to their existence, and so that is about all we know. The purpose of the caves is equally evasive, with no artifacts to show that they were used as tombs, no signs of any mining having been done, and there are no traces of anyone ever having inhabited them. They are just there, their meaning for existing just as inscrutable as the identity of their creators. All that can be known is that these caves took an enormous amount of manpower and time to create, so they must have been important for something to justify such a massive and ambitious project.
Just as perplexing is the mystery of how they were built. In total, it is estimated that around 1,000,000 cubic meters of rock and dirt would have had to be removed, which would have taken around 1,000 workers working 6 years straight, laboring day and night to accomplish, and yet there is no mention of any such project underway in the historic records, nor any clue as to where all of that rock went. Then there is the remarkable precision in the workmanship and the way the caves are so incredibly symmetrical and accurately laid out. Interestingly, the caves are all very similarly designed and laid out, with indeed some of the caves almost identical to each other, so how did they do that without any modern equipment? One Yang Hongxun, an expert at the Archaeological Institute of Chinese Academy of Social Sciences, has said of this:
At the bottom of each cave, the ancient builders wouldn't be able to see what the others were doing in the next grotto. But the inside of each cave had to be parallel with that of the other, or else the wall would be holed through. Thus the measure apparatus should have been very advanced. There must have been some layout about the sizes, locations, and the distances between the caves beforehand.
This is not to mention that it is uncertain even what tools the builders used, with no signs of any tools and no hints as to how these caves were dug. Also odd is the strange presence of numerous tiny chisel marks along the walls that are so symmetrical and uniform to look almost as if they were produced by some sort of machine, and which would have taken a mind-boggling amount of work to meticulously etch by hand. Their significance, of course, is just as enigmatic as anything else about this place. Adding to all of this is that the builders would have had to have done this down in the dark, yet there is no evidence of torches having been used, nor any other source of light, so how could they see down there in the eternal gloom? However they did all of this, it is a remarkable feat of engineering and made even more so by how incredibly well-preserved the caves are. Considering that they are thousands of years old, one would expect that there would be some collapses or signs of wear or damage, yet there are none and the caves are remarkably pristine.
Although they have been studied by scientists and a few are even open to tourism, no one has ever been able to figure out all of the pieces to the mystery of the Longyou Caves. We don't know who built them, how they did it, or why. They are a complete enigma, buried down there underwater for millennia with their secrets long gone with those who crafted them. In the void of any new findings on the mysterious complexes it is quite likely that we will never get the answers we seek, and that these caves will continue to remain curious anomalies flitting out past our understanding.