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The Longyou Caves or Grottoes | Cosmick Traveler Ancient Humans, Ancient Aliens, Ancient Times, Ancient Art, Ancient History, Mysteries Of The World, Ancient Mysteries, Ancient Underground City, Ancient Technology
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This picture is often found together with pictures of the Longyou caves. But according to this website, it is actually from a Zhejian tunnel. Zhejian is north of Longyou. I have not found any more …