Ever since Plato first wrote about the mysterious island of Atlantis, it has captured the imagination of adventurers and academics alike. Was Atlantis merely a myth, or could it have actually existed in the remote past? Did Atlantis just disappear as Plato described? And could it have been the home of an advanced civilization that created the human race? Ancient Astronaut Theorist Giorgio A. Tsoukalos explores the most recent discoveries related to the centuries-old story of Atlantis. By investigating a series of clues, Tsoukalos endeavors to narrow down the possible location of Atlantis. Could evidence be found in a strange egg-shaped stone in Portugal? What secrets can be uncovered on the island of Santorini, Greece? Could Atlantis have been an empire with a network that stretched around the world? Or was it something else entirely? Something that, perhaps, came from the stars?

At the height of World War II, the Nazis engaged their top scientists to develop "wonder weapons"--weapons that were so scientifically advanced they could have turned the tide of the war against the Allies. According to testimony, one of the top-secret projects was code-named "Die Glocke." Die Glocke was believed to be a bell-shaped time travel device that could soar through the sky and eventually reach the speed of light and beyond. Did Die Glocke actually exist? And if so, could it have been based on alien technology? Theorist Giorgio A. Tsoukalos travels from Poland to Pennsylvania on the trail of the Nazis' "wonder weapon." Did the Nazis find advanced knowledge in ancient texts that enabled them to develop anti-gravity technology? And was the construction of a time travel device made possible by reverse-engineering extraterrestrial technology?

Host Zach Quinto sets out to discover whether Aliens exist and what evidence we have to prove it. He meets with several people who say they have encountered extraterrestrial life.

Are we alone in the universe? With every new UFO sighting, we ask this age-old question. To find out, we'll hunt for eyewitnesses to large-scale otherworldly encounters and pore through declassified government data on UFOs in our airspace.

For everyday heroes in law enforcement and the military, their mission to serve and protect is put to the ultimate test when they come face to face with dangerous UFOs. Through dramatic reenactments of actual UFO classified files and expert interviews, this special explores the lengths that people on the front lines will go to keep civilians safe from extraterrestrial encounters.

The mysterious Mediterranean island of Malta lies south of Sicily and is home to megalithic structures built by a mysterious prehistoric society. According to scholars, the massive blocks even pre-date the Great Pyramid of Giza. Just who were the people that built these sophisticated structures? Local folklore describes Malta as being the home of giants and the legendary one-eyed creature known as Cyclops. Could these stories be true--or could they offer clues to an extraterrestrial connection? Ancient Astronaut theorist Giorgio Tsoukalos investigates Matla's giant stone structures, unexplained rock carvings and mysterious elongated skulls. Could these strange antiquities be connected--and might they prove that there was a highly advanced civilization on Malta in the remote past--one that was perhaps in contact with ancient astronauts?

A mysterious rock bearing a cryptic design was discovered in Roswell, New Mexico in 2004. Now coined "The Roswell Rock," this piece of stone is unusually smooth and possesses unique magnetic properties. Even more intriguing is that the motif on the rock--a sequence of triangles and crescents--is an exact match to a crop circle found in England nearly two decades ago. Ancient Astronaut Theorist Giorgio Tsoukalos sets out to determine the origin of this intriguing stone. Through a series of experiments Tsoukalos unveils whether the Roswell Rock is merely a man-made fabrication or something much more. How could the precise design have been created without leaving evidence of altering the stone? Why does this small rock react to magnets? And most baffling of all--why does the design match a crop circle that appeared more than 4,000 miles away from the Nevada desert?