Season
- Season 0 2009-03-08
- Season 1 2010-04-20
- Season 2 2010-10-28
- Season 3 2011-07-28
- Season 4 2012-02-17
- Season 5 2012-12-21
- Season 6 2013-09-30
- Season 7 2014-01-24
- Season 8 2014-06-13
- Season 9 2014-10-31
- Season 10 2015-07-24
- Season 11 2016-05-06
- Season 12 2017-04-28
- Season 13 2018-04-27
- Season 14 2019-05-31
- Season 15 2020-01-25
- Season 16 2020-11-13
- Season 17 2021-08-06
- Season 18 2022-01-07
- Season 19 2023-01-06
- Season 20 2024-01-05
- Season 21 2025-02-07
Ancient Aliens - Season 2 Episode 4 Underground Aliens
7.00 42 minutes If extraterrestrials influenced human history, can evidence of their existence be found in hidden tunnels and caverns around the world? Could a cave in Ecuador contain metallic books inscribed with secrets of alien technology? Was an ancient underground city in Turkey built with alien help... or as a refuge from an alien attack? Rumors of the U.S. military working alongside aliens in a secret base inside a mesa in New Mexico continue to swirl, Native American legends mention strange inner-Earth beings, and recent archaeological discoveries in the Yucatan may point to an extraterrestrial reality behind.
