The ancient ruins of Puma Punku have mystified archaeologists ever since their discovery hundreds of years ago. The massive stones are precisely carved into blocks that are unlike anything found anywhere else in the world. Is it possible that the ruins of Puma Punku offer evidence of advanced technology being used in the ancient past? And if so, might this technology have been provided by alien beings--beings who ultimately destroyed the site to conceal whatever they built? Ancient Astronaut theorist Giorgio A. Tsoukalos explores the construction and mysterious history of one of the most unique ancient sites on Earth. What was the purpose of the vast building at Puma Punku? Why is there no evidence of the precision tools required to create the unique blocks and sophisticated masonry found there? What could have destroyed this massive structure? Is it possible that Puma Punku is thousands of years older than previously thought?

Nazca remains one of the most mysterious sites on Earth. The vast desert floor is covered with hundreds of ancient geoglyphs depicting animals, human-like figures, and strange geometric designs. But, many of these glyphs are so large they can only be fully viewed from the sky. Perhaps even more intriguing are the strange flat-topped mountains that appear to have had their peaks sliced off and a band of man-sized holes that stretch for almost two miles across the desert. Could these ancient geoglyphs and mysterious landscapes hold the key to proving Earth was visited by aliens in the distant past? Ancient Astronaut theorist Giorgio Tsoukalos, along with author David Childress, investigates the origins and meanings of the mysterious symbols and shapes found in the desert of Peru.

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?

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?

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?

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?

Ancient Astronaut Theory has existed in popular culture for nearly 50 years, asking the question whether extraterrestrials visited Earth in the remote past. All around the world there are examples of physical evidence that suggest humans are not alone in the universe. But has this evidence been left behind for a purpose? Is it in fact a series of clues, or Alien Code, that we are meant to decipher? Ancient Astronaut theorist Giorgio A. Tsoukalos investigates unexplained mysteries from every corner of the world. The evidence shows that many ancient sites, and even modern ones like Roswell, all seem to be associated with legends and reports of someone or something coming down from the sky. Tsoukalos' research demonstrates that many of these sites share a common symbol or shape--concentric circles. What is the significance of these designs, and is it possible they contain a coded, mathematical message left by alien visitors in the remote past?

We are not alone. A mysterious email leads us to what could be a massive underwater UFO base off the Malibu Coast. Could an alien satellite, nicknamed the Black Knight, be spying on us from orbit? An investigation of Area Fifty-One takes a dangerous turn...and what is Area Fifty-Two?