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.

Ancient Aliens has followed investigators across the globe as they've gone directly to the sites where signs of alien life have been found. Now, Giorgio Tsoukalos takes a look back at the most incredible evidence ever uncovered that could offer definitive proof that we are not alone in the universe.