Longyou Caves are a series of large artificial caverns located at Phoenix Hill, near the village of Shiyan Beicun on the Lan River in Longyou County, Quzhou prefecture, Zhejiang province, China.
In June, 1992, a villager named Wu Anai, decided to pump the water out in one of the locally known caves revealing the first of many man-made caves in the region. After 17 days pumping, enough water had been removed to reveal the cave including several carved stelae, thus confirming his idea that they were not natural reservoirs at all, but rather man-made. The floor of the grotto occupies more than 2,000 square meters, with the tallest point of the cave exceeding 30 meters. The four steles of cave 1 are symmetrically distributed. Following this discovery, he continued to pump out another four caves only to find that they all bore the same markings on the walls and ceilings.They are considered by Chinese to be the 'Ninth Wonder of the Ancient World'
How were they constructed?
A rough estimation of the workload involved in building these five caves is awe-inspiring. The quantity of rock that would have been removed in the overall excavation of the grottoes is estimated to be nearly 1,000,000 cubic meters. Taking into account the average digging rate per day per person, scientists have calculated that it would take 1,000 people working day and night for six years to complete. These calculations are based purely on hard labour, but what they haven’t taken into account is the incredible care and precision of the sculptors, meaning that the actual workload would far surpass the theoretical estimation. As for how they were constructed and what tools were used, it is still unknown. No tools have been found in the area, and, as we will explore later, scientists still don’t know how they achieved such symmetry, precision, and similarity between the different caves.
No traces of construction Despite their size and the effort involved in creating them, so far no trace of their construction or even their existence has been located in the historic record. Although the overall excavation involved almost a million cubic metres of stone, there is no archaeological evidence revealing where that quantity of stone went, and no evidence of the work. Moreover, there is not a single historic document that refers to them, which is highly unusual considering the sheer scale of the project. Their origin is a complete and utter mystery.
How did the caves remain so well preserved?
One of the most interesting and challenging questions is how the caves have been able to keep their structural integrity for more than 2000 years. There are no signs of collapse, no piles of rubble, and no damage despite the fact that in some areas the walls are only 50 centimetres thick. Over the centuries, the area has gone through numerous floods, calamities and wars, the mountains have changed their appearance and exposed stones have been weathered, but inside the caves, the form, patterns and markings are still clear and precise – it is as though they were built yesterday.
How did the builders work in the dark?
Due to the great depths of the caves, some areas at the bottom, which are not exposed to the opening above, are pitch-black. Yet even those dark areas are decorated with thousands of parallel lines on the walls, columns, and ceiling. So how did the ancient people work in the dark? According to Jia Gang, a Tongji University professor specializing in civil engineering: "There should be lamps, because the cave's mouth is very small, and the sunbeam could only shine in the cave at a certain angle during a certain period of time. As one goes deeper into the cave, the light becomes dimmer. At the cave's bottom, which is usually dozen of meters from the mouth, one could hardly see anything." However, this was at least two millennia ago and nothing that could have been used for lighting has been found.
Were the caves meant to be connected?
All of the 36 grottoes are distributed across an area of only one square kilometre. Considering such a high density, one cannot help asking whether some grottoes were meant to be connected. What would be the purpose of making so many separate caves in such a tight area without connecting them? In many areas, the walls between the caves are very thin, only 50 centimetres, but they were never linked so it appears they were intentionally kept apart. What’s more, many of the caves are almost identical to each other.
Who built them? Nobody has any idea who built the caves. Some scientists have claimed that it was not possible or logical for such as mammoth job to have been undertaken by regular village people. Only the emperor and the leaders could have organised such a huge project, like the construction of the Great Wall, which was built to defend against invasion from the outside. But if it was commissioned by an Emperor, why are there no historical records of its construction?