Underground Aliens Emerge Across the Globe (S2, E4) | Ancient Aliens

If extraterrestrials influenced human history, can evidence of their existence be found in hidden tunnels and caverns around the world? In Season 2, Episode 4, "Underground Aliens." Find out more about the show and watch full episodes on our site: "Ancient Aliens" explores the controversial theory...

44 min - Space & the Universe - HISTORY

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