Ancient Aliens

According to some Ancient Astronaut theorists, entities that have been described as ghosts, angels and extraterrestrials are actually visitors from unseen realms and they walk on Earth.

Today, more people than ever believe that unidentified flying objects are of alien origin; exploring the possibility that they are capable of bending both time and space.

Giorgio Tsoukalos takes a look back at some of the structures visited all over the world that could provide undeniable evidence of extraterrestrial contact.

"Ancient Aliens" has examined the oldest and most mysterious rock art on Earth up close, and Giorgio Tsoukalos takes a look back at the incredible hieroglyphs, petroglyphs, and geoglyphs that he believes tell a worldwide story of alien visitation.

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

The team investigates the world's oldest and most incredible relics up close; Giorgio Tsoukalos takes a look back at the most mysterious artifacts from all over the globe, those he believes provide undeniable proof of extraterrestrial contact.