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

Ancient Aliens has investigated the world's oldest and most incredible relics up close and in person. Now, Giorgio Tsoukalos takes a look back at the most mysterious artifacts from all over the globe – artifacts that he believes provide undeniable proof of extraterrestrial contact.