"Ancient Aliens" is looking at alien petroglyphs around the world; from strange, human-like figures to flying craft and carvings of what appear to be astronauts...

Ancient Aliens is counting down the top ten mysteries of the deep, from sunken continents to puzzling ruins on the ocean floor and even artifacts that might be remnants of Atlantis. Could these underwater mysteries provide a record of extraterrestrial visitation?

For thousands of years, people have held the belief that everyday objects can possess hidden energy. Talismans are seen as providing protection, good fortune, and some are even thought to embody a higher power. Could it be that what fuels our faith in talismans is not superstition, but a real connection to something beyond our world?

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?

More than 3,000 years ago, the ancient Greeks built an empire that is considered the birthplace of Western Civilization, and they credited their most monumental achievements to gods like Zeus, Apollo, and Poseidon. But is it possible that these powerful beings from Mt. Olympus were, in fact, extraterrestrial visitors to Earth?

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?

Around the world and throughout history, people have reported seeing very similar types of unidentified objects in the sky. Now, Ancient Aliens is counting down the top ten alien craft, from V-shaped objects to orbs of light to flying saucers. Could the ubiquity of these sightings provide evidence of extraterrestrial visitation?

"Ancient Aliens" is counting down the world's top 10 mysterious islands, including sites said to be home to giants, remote landmasses that are home to massive megalithic structures, and even islands that disappear into thin air...

Ancient Aliens is counting down the world's top ten mysterious devices, from strange, grooved disks found in a cave in China to an ancient Greek computer to an incredible crystal skull unearthed in Mexico. Might these sensational artifacts provide evidence of extraterrestrial visitation?

Ancient Aliens is counting down the world's top 10 pyramid sites, from a valley in Peru with over 250 hidden pyramids to an ancient Greek city with mysterious 4,800-year-old ruins to Egypt's famous Giza Plateau... Could the extraordinary structures that stand at these sites provide evidence of extraterrestrial visitation?

Enormous, megalithic structures of mysterious origins. A vast underground complex containing the remains of what some believe to be otherworldly beings. Could the ancient mysteries that exist on the Mediterranean islands of Malta be connected to local legends of alien visitation–and giant hybrid beings?

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?

The vast Alaskan wilderness is well known for mysterious disappearances, electromagnetic anomalies, stories of strange creatures, and is a hotspot for UFO sightings. Could Alaska's many mysteries be due to a presence that is not of this world?

The Center for the Study of Extra-Terrestrial Intelligence defines a "Close Encounter of The Fifth Kind" as direct human contact and communication with extraterrestrial life. But is this a classification that will only be useful in the distant future, or have such encounters already taken place… and within the highest levels of the U.S. government?

Meteor impacts have significantly altered our world, creating the perfect environment for the rise of humankind and delivering metals essential to the development of an advanced civilization. But could new evidence reveal that celestial objects have been directed to Earth by an alien intelligence?

The Mutual UFO Network–better known as MUFON–is the world's leading organization devoted to the scientific investigation of unidentified aerial phenomena and other unexplained encounters. With more than five decades of investigations, could MUFON's extensive database contain definitive proof of extraterrestrial visitation?

The towering obelisks of ancient Egypt weigh hundreds of tons and each was perfectly carved from a single granite rock. While mainstream scholars identify them as monuments to the pharaohs, Ancient Astronaut Theorists suggest they may have served a technological purpose–they powered a technology that allowed for communication with the gods who came from the stars.

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?

More than 10,000 crop circle formations have been documented in over 50 countries, and many display properties that defy conventional explanations. Are they of otherworldly origin? And if so, what is their purpose? Could it be that reconnection with our alien ancestors will only come when we finally crack the crop circle code?

Studies have shown that up to 70% of all UFO sightings happen in so-called 'hotspots' where reports of visions, mysterious lights and unusual phenomena are regularly witnessed--and not only in modern times, but dating back thousands of years. Could there be something about these locations that attracts extraterrestrial visitors?