An ancient figurine of a modern-day airplane. A primitive statue of a man in a spacesuit. Mysterious crystal skulls whose origins are entirely unknown. For more than a decade on Ancient Aliens, we've traveled the globe and investigated strange objects found on every continent on Earth. We're counting down the top ten alien artifacts. Objects that could provide evidence that extraterrestrials once walked among us.

We're counting down the world's top ten alien encounters, from the first reported abduction event to mass UFO sightings over New York's Hudson Valley to an incident in ancient Rome that changed the course of human history. Could these incredible accounts be actual encounters with visitors from the stars?

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? Ancient Astronaut theorists Giorgio A. Tsoukalos, David Childress and William Henry will be joined by Rabbi Ariel bar Tzadok and filmmaker Caroline Cory to investigate the mystery of the Human genome, in an attempt to determine if human beings are the product of an extraterrestrial experiment. Might the ultimate proof we are not alone in the universe be hidden in our own genetic code?

Mount Shasta in northern California is known as a hotbed of strange events, from Big Foot sightings to UFO encounters to hikers vanishing without a trace. Could the mountain's unique geology and placement on Earth be attracting beings from other worlds... and even other dimensions?

Ancient Aliens is counting down the world's top ten alien cover-ups, from the famous Roswell Incident to a secret military base rumored to be housing ET technology to recently released UFO videos captured by cameras on Navy fighter jets. Has there been a massive cover-up regarding the truth about an extraterrestrial presence on Earth?

Ancient Aliens is counting down the world's top ten most mysterious sites, from the towering Moai statues of Easter Island to the enormous megalithic blocks of Stonehenge to the precision cut stones of Puma Punku. Could these extraordinary places provide evidence of extraterrestrial visitation?

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? Ancient Astronaut theorists Giorgio A. Tsoukalos, author David Childress and investigative mythologist William Henry will examine a recently discovered "lost city" in Peru that has upended the historical timeline of South America, revealing that civilization emerged here thousands of years earlier than previously thought. Could it also provide evidence that Peru's incredible ancient sites were built with the help of extraterrestrials?