If scientists, closing their eyes, call the megaliths of Siberia a "natural phenomenon", then in the case of a small archipelago in the Pacific Ocean they simply have no choice but to shrug their shoulders and admit that our modern scientific theories simply do not work here.
Nan Madol consists of many tiny artificial islands made of basalt monoliths and coral blocks. Buildings have survived here, which, of course, were dubbed "temples", and therefore the archipelago itself began to be considered a "religious center".
But if you think about it: to create entire islands of basalt for religious purposes? Historians clearly overestimate the religious component in the life of ancient civilizations.
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Naturally shaped basaltic megaliths (usually hexagonal pillars) are set on top of a coral reef. In total, there are thousands of such blocks of various sizes. Some are 5 meters long and weigh more than 5 tons, and there is a megalith and 50 tons.
Of course, the scientists assumed that these blocks were brought here from other islands on rafts. But this does not stand up to criticism, since the labor costs in this case are simply prohibitive.
The point is not so much the weight of the stones, but their quantity: not only the foundation, but the entire island was built with such a technique:
Here we can assume that the archipelago was once a single island, because now many buildings have gone under water:
There are islands with similar architecture not far from Nan Madol. These are Lelu (Kusaiye), Guam and Yap. The latter is famous for its "Rai stones":
Why the ancients needed to build artificial islands next to a large natural island is a mystery.