Has Antarctica served as a home base for extraterrestrial visitors to Earth for thousands of years?

Giorgio Tsoukalos takes a look back at the most compelling investigations of all, and events that he believes represent real encounters with extraterrestrial visitors.

Giorgio Tsoukalos takes a look back at the most extraordinary encounters that, as far as he's concerned, provide evidence of an extraterrestrial presence on Earth.

Ancient underwater cities can be found around the globe, but could these aquatic worlds be the ruins of unknown civilizations--or even proof of extraterrestrial visitations?

Could paranormal activity be explained by beings entering our world from other dimensions? According to some Ancient Astronaut theorists, entities that have been described as ghosts, angels, and extraterrestrials are actually visitors.

Telepathy. Precognition. Psychokinesis. Is it possible that the human brain possesses extraordinary untapped abilities--given to us by extraterrestrial beings? Abilities that, once harnessed, will enable the next step in the evolution of humankind?

Scientists now know that seven human-like species lived alongside Homo sapiens for thousands of years. But why is it that only humans survived? Is it possible that we were the product of extraterrestrial experimentation?

The South American nation of Peru is famous for its megalithic ruins, colossal geoglyphs and the Incan civilization. It's one of the most mysterious places on Earth--but could it also be a site of extraterrestrial visitation?

Ever since the first atomic bomb was detonated in 1945, UFOs have been reported at nuclear facilities all over the world. Is it possible that extraterrestrials are monitoring humanity's nuclear capabilities? But why? Does this constitute a threat?

When Spanish Conquistadors obliterated the historical record of the Maya in the 16th century, did they wipe out evidence that ancient people traveled to the Americas from all over the world--and in flying craft provided by extraterrestrial visitors?