Former police detective Dave Paulides investigates a mysterious disappearance at Mount Shasta, in this clip from Season 17, "The Mystery of Mount Shasta." Watch all new episodes of Ancient Aliens, Fridays at 9/8c, and stay up to date on all of your favorite shows on The HISTORY Channel website ...

Considered by many to be the greatest civilization in the history of the Americas, the Maya thrived for more than 2,000 years. See more in this scene from Season 20, Episode 11, "Mysteries of the Maya." Watch all new episodes of Ancient Aliens, Fridays at 9/8c, and stay up to date on all of ...