Tune in to Alien Invasion Week on History starting Monday 9/30 through Friday 10/4 for new Ancient Aliens, plus the premiere of In Search Of, new UFO Specials and More! The Carnac Stone are the largest collection of standing stones in the world, but nobody really knows why they were built in ...

There is a stone platform underneath ancient Greek and Roman ruins that ancient astronaut theorists believe was used as a platform to launch extraterrestrial aircraft in this clip from Season 8, "Mysterious Structures". #AncientAliens Subscribe for more from Ancient Aliens and other great HISTORY ...