Ancient Aliens: Top 3 UNBELIEVABLE Alien Petroglyphs

Are these petroglyphs proof that Earth has been visited by extraterrestrials?! See more in Season 19, Episode 20, “The Top Ten Alien Petroglyphs.“ Watch your favorite episodes of Ancient Aliens on The HISTORY Channel website at #AncientAliens Subscribe for more from Ancient Aliens and other great The HISTORY Channel shows: Find out more about the show and watch full episodes on our site: Check out exclusive The HISTORY Channel content: History Newsletter - Website - Facebook - Twitter - “Ancient Aliens“ explores the controversial theory that extraterrestrials have visited Earth for millions of years. HISTORY® is the leading destination for award-winning original series and specials that connect viewers with history in an inf