Ancient Aliens - Season 21

Ancient Aliens is counting down ten of history's most astonishing discoveries – breakthroughs that challenge traditional beliefs about human history. From a lost city hidden in the Andes to mysterious metal spheres that are not of this world and a sunken city that was said to be the home of the gods, could these discoveries provide proof of extraterrestrial contact?

Ancient Aliens is counting down the world's top ten most mysterious monoliths, from a 500-ton stone believed to represent an ancient UFO, to giant statues said to have been created with advanced technology, and ornate pillars that depict otherworldly visitors. Could these extraordinary standing stones provide evidence of extraterrestrial visitation?

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?

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?

Ancient Aliens is counting down ten of history's most compelling -- and covert -- projects that study the UFO phenomenon. From clandestine government organizations to agents that silence UFO witnesses and secret programs to reverse-engineer alien technology, are these mysterious projects evidence of contact with extraterrestrials?

Ancient Aliens is counting down ten mysterious mountains that are notorious for otherworldly phenomena.  From a summit in Sri Lanka that is said to be a portal to other worlds, a volcano in Washington that was at the center of a famous UFO sighting, and a mesa in New Mexico believed to contain an alien base, could these strange peaks provide evidence of extraterrestrial contact?

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?

Across the globe, reports of mysterious glowing orbs are on the rise. Their movements frequently defy the laws of physics, and now they are even being reported near military bases, ships, and nuclear weapon facilities. Do they represent a non-human intelligence? And if so, why are they here? 

Dr. J. Allen Hynek is best known as the notorious government UFO debunker who became one of the founding fathers of ufology. Was Dr. Hynek right when he ultimately concluded that there is a non-human intelligence on Earth?

Volcanoes are Mother Nature's most fearsome and volatile creation. They have inspired countless myths and legends, but curiously, they are also major hotspots for UFO sightings.

Throughout the ancient world, there are depictions of mysterious figures that appear to be half human and half bird. In many cultures, they are revered as divine and have magical abilities.

All over the world, there are people who claim they have been abducted by aliens. Since the 1970s, a growing number of researchers have dedicated their lives to uncovering what is behind this disturbing phenomenon.

Thousands of years ago, people all over the world described encounters with enormous, human-like beings, and some archaeologists even claim to have found skeletons of extraordinary size. Could it be that the giants of myth and legend, truly existed?

In the age of smartphones and social media, more evidence of otherworldly activity has come to light than ever before. From a giant "shadow monster" witnessed outside a Miami mall to reports of ET encounters in Las Vegas.

From ancient sites like Stonehenge to the crop circle phenomenon and modern-day UFO sightings, Great Britain is a place of countless mysteries. Could it be that throughout history, this island has been a destination for extraterrestrial visitors?

The ancient legends of the Norse read like modern science-fiction, with powerful gods wielding incredible weapons and high technology. Could it be that these mythological tales are based on real encounters with extraterrestrial beings?

Japan is a land rich with ancient mysteries, and recently, it has also become known as a UFO hotspot. Could it be, as Ancient Astronaut Theorists suggest, that this island nation has a long history of extraterrestrial activity?

In every corner of the world, archaeologists have found strange, elongated skulls. Did our ancestors modify the shape of their skulls to resemble extraterrestrials? And might it even be possible that some of these skulls are of otherworldly origin?

In the western Pacific Ocean is a vast area known as Oceania that is home to the world's most remote and mysterious islands. They are known for massive stone structures, statuary strange figures, and countless legends of otherworldly visitors.