Ancient astronaut theorists speculate the causes for mysterious disappearances and sightings at Skinwalker Ranch. See more in this clip from Season 21, Episode 8, "The Glowing Orb Phenomenon." Watch full episodes and stay up to date on all of your favorite shows on The HISTORY Channel website ...

Check out these epic doomsday theories. See more in this Ancient Aliens compilation. Watch full episodes and stay up to date on all of your favorite shows on The HISTORY Channel website at http://history.com/schedule. #AncientAliens Subscribe for more from Ancient Aliens and other great The ...

Ancient astronaut theorists explain the hollow earth theory. See more in this clip from Season 1, Episode 6, "Mysterious Underground Worlds." Watch full episodes and stay up to date on all of your favorite shows on The HISTORY Channel website at http://history.com/schedule. #AncientAliens ...

A mysterious mountain in northern Italy has stood witness to strange sightings in the sky and unexplainable phenomena for hundreds of years. Could its position on a powerful Earth energy line be attracting extraterrestrial visitors? See more in Season 14, Episode 15, "The Alien Mountain." ...

Check out this epic compilation of Travis Taylor's biggest moments. See more in this Ancient Aliens compilation. Watch full episodes and stay up to date on all of your favorite shows on The HISTORY Channel website at http://history.com/schedule. #AncientAliens Subscribe for more from ...

Did aliens really help to shape our history? See more in this two hour marathon from Ancient Aliens. Watch full episodes and stay up to date on all of your favorite shows on The HISTORY Channel website at http://history.com/schedule. #AncientAliens Subscribe for more from Ancient Aliens and ...

Underneath a Mexican peninsula lies a secret Mayan Temple never spoken of before now. See more in this clip from Season 1, Episode 5, "Mysterious Underground Worlds." Watch full episodes and stay up to date on all of your favorite shows on The HISTORY Channel website at ...

Megalithic monuments linked together by electromagnetic energy... Prehistoric ruins arranged across vast distances in straight lines... And advanced mathematics carved into landmarks more than 5000 years ago. See more in Season 1, Episode 14, "Stargates and Secret Messages." Watch full ...

Have you ever wondered if aliens are real? From mysterious lights in the sky to unexplained UFO encounters, these sightings will leave you speechless! Governments, including the Pentagon and NASA, have released reports on unidentified aerial phenomena (UAPs)—but what are they really? Are we ...

The Foo Fighters UFO Encounters of World War II | Episode 19 | Full Documentary | Europe, WWII, Aerial UAP Sightings Over Combat Zones During the height of World War II, Allied and Axis pilots reported glowing, fast-moving orbs that seemed to defy the laws of physics. These mysterious ...

82 Clearest UFO & Alien Sightings Caught on Camera I Distinct Footage! Are you ready to uncover the 87 most shocking UFO encounters that defy physics and leave skeptics speechless? From mysterious metallic spheres stalking aircraft to jaw-dropping sightings during solar eclipses, these UFO ...

The Frank Smythe UFO Sighting of 1933 | Episode 18 | Full Documentary | Mount Everest, Himalayas, High-Altitude UAP Encounter This episode explores the Frank Smythe UFO sighting of 1933 during the British Mount Everest expedition—one of the earliest high-altitude UFO encounters ever ...