Ancient cultures around the world tell stories of strange objects witnessed flying in the sky. But are these tales fiction, or might people living thousands of years ago actually have seen extraterrestrial crafts descending from the heavens? In the Hebrew Bible's Book of Ezekiel, the prophet describes a fiery chariot containing wheels within wheels, powered by angels. In ancient Ethiopian texts, King Solomon of Israel gave the Queen of Sheba a flying carpet, and traveled on one himself throughout the Middle East. And Chinese mythology explains that the god Huang Di emerged from the belly of a fire-breathing dragon to become China's first emperor. Could these accounts of fiery chariots, flying carpets and fire-breathing dragons really be descriptions of misunderstood technology involving mysterious crafts? Have otherworldly spacecraft been soaring across Earth's skies for thousands of years? What were our ancestors really describing in their ancient stories?

All over the world there are megalithic stone structures whose construction baffle stonecutters, scientists and archeologists. Is it possible that ancient humans managed to move and cut these gigantic rocks with the help of alien technology? From the 3,000 megalithic stones in the French village of Carnac to the precision-cut blocks at Puma Punku in Peru to the 12,000 year-old circular structures of Gobekli Tepe, carved multi-ton megaliths are found throughout ancient cultures. Yet the mystery of how the stones were cut and moved to build these formations remains. One possible answer may be found at Coral Castle, Florida, where in the 1930s an anti-gravity device was allegedly used to move 30-ton coral blocks to create the giant sculpted gardens. Massive stone ruins mark what we believe to be ancient burial sites, temples and astronomical observatories--but how these megaliths were built cannot be explained.

A 2,000-year-old computer... a power plant inside the Great Pyramid... and a Nazi-era time machine with roots in the ancient history. Throughout the world, there are artifacts and stories that point to advanced technology in the distant past. Could these devices be products of our ancestors' imaginations or might ancient man have had access to extraterrestrial technology? Were ancient Egyptians able to generate electricity, perhaps even illuminating the corridors of the royal tombs with electric light bulbs? Did top-ranking Nazis secretly develop a time-travel machine that was used as an escape vehicle after their defeat in Europe? Could the Ark of the Covenant have been a sonic weapon? Many of the world's most mysterious devices have been here for thousands of years. Could they have been built with the help of extraterrestrial beings?

The Reptilian alien is a fixture of science-fiction, from H.P. Lovecraft's tales of Valusians to the Cardassians in Star Trek, to the Visitors of the television series V. But could ancient myths about reptilian creatures provide evidence that they are more than just a pop-culture creation? Legends of serpent beings can be found on every continent. The Bible, the Quran and the ancient texts known as the Nag Hammadi codices all describe reptilian entities interacting with humans. In Mexico and Central America people worshiped the feather serpent god called Kukulkan or Quetzalcoatl. In India, the Nagas are half-human half-reptile gods who live underground in a place called Patala. And in China and Japan, many emperors claim to be the descendants of dragons. Could these stories represent real Reptilian beings that people all over the world actually encountered in the ancient past?

He is one of the most prolific inventors of the 20th century--and the man that actually electrified the world. Nikola Tesla shepherded mankind to a new industrial era and laid the groundwork for today's technological age--but could that have been by some otherworldly design? A man shrouded in mystery and intrigue, Tesla would speak about obtaining insights in a flash of genius, how he could visualize his inventions in full-detail and manipulate them in his mind, and his compulsion to invent the future. But he also claimed to have direct communication from intelligent beings on other planets. Is it possible that this alleged mad scientist, so far ahead of his time, was actually a human "receiver"? A being tapped to advance mankind--and pave the way for a future reunion with our alien ancestors?

It has been called the key to the universe and possibly the most important scientific breakthrough of all time. Could the so-called "God Particle" reveal the truth about our origins? And might clues to its significance have been left here on Earth thousands of years ago by extraterrestrial beings? The age-old question, "where did we come from?" remains a mystery, but in 2012, scientists at CERN laboratory announced the discovery of the "God Particle"--the subatomic particle that is believed to give mass to matter--and offers a closer understanding of just how the universe began. The discovery seemingly pitted science against religion. But could science and religion actually be kindred spirits? Many ancient religions and mythologies describe the origins of the universe in ways very similar to today's scientific explanations and proclaim that this information was given to them by otherworldy beings.

Stories of strange encounters accompany many of history's major events. Is it merely coincidence? Or might it be evidence of extraterrestrial intervention? In ancient myths from cultures around the globe, gods are often portrayed intervening in human affairs. The Sumerian gods are said to have created mankind; the Hebrews believe God gave Moses man's first laws, the Ten Commandments, and the angel Gabriel reportedly shared divine wisdom with the prophet Muhammad. But is it possible that these supernatural visitations were not actually the work of the gods--but rather a race of extraterrestrials using advanced technology to create and shape our civilization? Ancient Astronaut Theorists believe aliens may have helped guide mankind in the remote past--and that evidence for this stunning conclusion can be found sprinkled throughout human history.

From the beginning of recorded history, humans have told stories about beings with super-human strength, super-sonic speed, and supernatural abilities. The ancients had heroic tales about Zeus, Thor, and Hanuman while today we have superhero stories about Superman, Batman, and Spider-man. Mythologists say these epic stories resemble each other because they may have all come from a common set of oral legends created eons ago by our earliest ancestors. But might there be another, more otherworldly reason that the world's heroic myths are so similar? Is it possible, as many Ancient Astronaut Theorists contend, that these stories are actually based on extraordinary-- and possibly extraterrestrial--beings that lived on Earth in the distant past?

Puma Punku in Bolivia features stone blocks, each carved with precision; the blocks lie scattered across the landscape, confusing archaeologists as to what the ancient site might have been.

The Aztecs built one of the world's most powerful and feared empires and they claimed that they were guided by a pantheon of more than a thousand gods who came to Earth from different parts of the universe. Could the incredible story of their rise to power and their sudden demise, reveal a history of extraterrestrial intervention in Mesoamerica?

Considered by many to be the greatest civilization in the history of the Americas, the Maya thrived for more than 2,000 years. Now, new evidence is being discovered that completely upends our understanding of this ancient culture... and might provide evidence that the Maya came in contact with extraterrestrial visitors.

Ancient Aliens is counting down ten of the most compelling UFO crashes that have been reported across the globe. From an acorn shaped object that crashed in the woods of rural Pennsylvania, to a mysterious craft that washed ashore in Japan and an earth shaking impact in Britain that defies explanation. Are these mysterious events proof that our planet has been visited by extraterrestrials?

Deep beneath the sands of Egypt lie 24 enormous sarcophagi, and every one of them is empty; discussing what purpose those giant tombs had served.

For more than four decades, award-winning journalist Linda Moulton Howe has covered the most mysterious phenomena on Earth. Could her investigations on everything from bizarre animal deaths to crop formations and alien abductions lead us to a profound new reality?

For thousands of years, humankind has attempted to make contact with beings from beyond Earth; now, the search for extraterrestrial intelligence is ramping up, with new technologies allowing individuals to explore the universe.

Dr. Jacques Vallée has many scientific degrees, is a best-selling author and is regarded as one of the internet's founding fathers. But he is best renowned for his groundbreaking work on the subject of UFOs, where his bold theories call into question our understanding of alien life.

Ancient Aliens is counting down ten of the most astonishing and unexplainable technologies in history. From mysterious golden orbs discovered in Mexico, to a sacred wooden box that could communicate with the heavens and an ancient tomb that is said to depict an astronaut. Might these sensational artifacts be evidence of otherworldly contact?

In the early 1900s, a modern-day prophet from the hills of Kentucky became a worldwide sensation: Edgar Cayce. He claimed to receive visions of both the past and the future while in a trance, he healed the sick, and alleged to have encounters with otherworldly beings. Could it be that Edgar Cayce was a vessel used to carry out an alien agenda?

For thousands of years, cultures around the world have held a belief in stargates through which beings have traveled to Earth from distant points in the universe and even other dimensions. Could such portals truly exist? And if we obtain the key to unlocking the stargates, will we find a cosmos teaming with life?

The discovery of the ancient megalithic site of Karahan Tepe in southern Turkey turned the world of archaeology on its head, displaying engineering skills far beyond what the people of the time were thought to be capable of. But could new evidence reveal that this more than 11,000-year-old complex was built not by humans…but giants?

For decades, incredible claims have been made about an extraterrestrial presence on Earth, and the government has gone to great lengths to discredit them.

Stories of god-like beings providing instruction to early humans, helping establish the first civilizations; exploring if mysterious figures who appear throughout history provide evidence that these otherworldly teachers have been here all along.

Many of the architectural marvels of the ancient world bear striking similarities to one another, even though they were built by civilizations that were separated by thousands of miles and are believed to have had no contact with one another. Separated by more than 7500 miles, the Giza pyramid complex in Giza, Egypt and the Avenue of the Dead in Teotihuacan, Mexico contain pyramids that are aligned with the constellation of Orion's belt. An ancient pyramid temple in Cambodia known as Baksei Chamkrong is an almost identical match for the Temple of the Jaguar in Guatemala. Many structures built using stone slabs that weighed over a hundred tons. But how did primitive people achieve such extraordinary feats? And why do we see such similarities? Could these sites have all been designed by alien architects?

Terrifying encounters at 40,000 feet. Pilot accounts of UFOs taking control of their aircraft. Entire jumbo jets disappearing into thin air. Since the dawn of aviation, pilots have experienced unexplainable events in the sky. Could they have witnessed aliens in our airspace?

In the 21st century, UFOs have gone from fringe science to mainstream obsession. A new generation of UFO hunters is employing incredible technology, and Unidentified Flying Objects are being openly investigated by the government. Are we closer than ever to understanding the strange events happening in our skies?