Scientists investigate the possibility that alien life-forms influenced human evolution, citing the existence of strange monuments around the world to support their theory.

Horizon investigates whether first contact with aliens has already occurred. The publication of 'Chariots of the Gods?' by Erich von Daniken is central to this documentary and some of von Daniken's claims of evidence of extra-terrestrial visitations.

An edited version of the 1970 German documentary "Erinnerungen an die Zukunft" (Chariots of the Gods), this examines the theory that aliens have landed on Earth in ancient times and were responsible for many of mankind's oldest mysteries.

An exploration into the ancient astronauts theory.

This documentary explores the historical settlement of the Sumerians in Mesopotamia during the Chalcolithic era.

Jason Martell and Tom Van Flandern lecture about Planet X, ancient astronauts at the 2008 Central Coast Science-UFO Symposium.

This documentary explores the Ancient Astronaut Theory, which posits that extraterrestrial life visited Earth in ancient times, leaving behind technological advancements and stories in which people refer to them as "gods."