A round the turn of the century, a number of huge tunnels were discovered in South America. After investigation, the scientists who discovered them found that they are not made by any humans, nor geological process. The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.

Professor of geology, Heinrich Frank, spotted a strange hole embedded in a hill at a construction site as he passed it on the highway, according to Discover . Frank returned to the tunnel, which had been uncovered during excavation, and crawled inside.

The tunnel was 4.5 meters (15 feet) long. Frank could tell that the tunnel was not made by geological forces, but nothing beyond that. At the end of the tunnel was a much bigger clue, that you probably still don't want to

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