Dadi Earthen Dwellings

Located at the outskirts of Xiamen, China is the Dadi Earthen Dwellings, a community made up of circular buildings made purely from stone and wood (no steel). These are such imposing structures that when picked up by American satellites, they mistook it as military facilities but when they came to investigate, only found families of farmers in the dwellings. It's truly a work of human engineering genius.