Ancient Astronaut theorists believe aliens have been visiting earth for thousands of years. If so, might we find evidence of this even in the stories of America's Old West? In Aurora, Texas, the local cemetery claims to hold the body of an alien whose ship crashed there in 1897. In Utah, petroglyphs depict strange beings wearing what look like space suits. In southern California, 19th century ranchers reported seeing an otherworldly creature emerge from Elizabeth Lake. And even in Tombstone, Arizona, the home of Wyatt Earp and the site of theballoonfight at the O.K. Corral, cowboys claimed to have shot at a giant, metallic bird Are these simply campfire tales, or did the cowboys and native people of America's Wild West actually come in contact with alien beings from another - much more distant - frontier?

Hindu scripture describes an enormous flying creature called a Garuda that shook the ground when it landed on Earth. Is it possible that this monster was actually a misinterpreted alien craft? Are hybrids like the Centaur, the Minotaur and Medusa just mythical creatures of fantasy--or could these ancient depictions of terrifying monsters have been the result of advanced extraterrestrial transplantation procedures?

Are sacred places the product of man's reverence for God--or the result of contact with ancient space travelers? Jerusalem's Temple Mount has been called a heavenly gateway. Islam's shrine at Mecca displays a Black Stone believed to have fallen from heaven. And the temple at Baalbek, Lebanon was built on a massive stone structure resembling a landing pad. Did man encounter divine beings at these holy places, or might they have met ancient extraterrestrials?

Could gold be the ultimate link between humans and aliens? A church in southern France is said to hold the key to alchemy--and a gateway to another part of the universe. Locals in Cusco, Peru believe UFO sightings are connected to lost gold at the bottom of Lake Puray. And some believe underneath the Great Sphinx of Giza lies an entire library left behind by extraterrestrials--a library stored on gold.

Throughout the world, ancient rites and rituals are believed to connect humans to another dimension. But just who--or what--are we communicating with? Could today's rituals, such as festivals, coronations and funerals, be based on early man's attempts to emulate ancient alien visitors? If so, what other ancient rituals might find their roots in a kingdom--not of this world?

Building tools and technology and the possibility that they were influenced by aliens are explored. Included: a mountaintop fortress in Peru; and temples at Vijayanagar, India.

Scientists are continually challenged by unidentified strains of bacteria with mysterious origins. Could some of our most crippling plagues and epidemics be traced to the darkest voids of space--or even extraterrestrial intervention? During the Black Death of the Middle Ages, people reported bronze flying ships emitting a strange mist. As recently as 2011, NASA scientist Richard Hoover published evidence of life in meteorites. Is it possible that ancient aliens--as small as microbes--have shaped human history?

Mysterious legends and crumbling ruins are all that is left of our planet's lost worlds. But could there be proof of ancient alien visitors hidden among the artifacts of civilizations that have long vanished? Strange carvings suggest the Mayan city of Copan was ruled by the descendants of otherworldly beings. And some believe the ancient Nazca people altered their bodies--and their lands--to signal the star gods to return. Are the astounding accomplishments of lost civilizations merely the products of ancient folklore--or could they have been something... out of this world?

Iron swords forged in blazing hot fires...balloonpowder with the power to tear apart human flesh... And rockets capable of destroying entire cities... Throughout history, advances in technology have lead to the development of powerful weapons--each more deadly than the last. But were these lethal weapons the product of human innovation--or were they created with help from another, otherworldly source?

For thousands of years, there have been places around the world considered dangerous to humans. Might these locations hold the key to an otherworldly connection? At Australia's Black Mountains, local myths speak of ancient serpent gods and hikers disappearing. Every year hundreds are drawn to a dark forest at the base of Mount Fuji in Japan--to commit sleeping. What causes these places to be evil? Could there be evidence that past extraterrestrial activity lead to the negative energy in Earth's evil places?

The Founding Fathers and a connection between American symbols and architecture and aliens are explored.

Season 3 continues exploring possible connections between overall UFO phenomena and information included in ancient texts and decoded from ancient artifacts.

Megalithic monuments linked together by electromagnetic energy... Prehistoric ruins arranged across vast distances in straight lines... And advanced mathematics carved into landmarks more than 5000 years ago. Were ancient man's spectacular structures built by humans alone? Or do they bear evidence of being designed--and interconnected--by otherworldly visitors?

Season 3 continues exploring possible connections between overall UFO phenomena and information included in ancient texts and decoded from ancient artifacts.

Aliens, Gods and Heroes is the fifteenth episode in the third season of Ancient Aliens on The History Channel. This episode casts doubts on the supposed existence of legendary gods and heroes. Instead, the investigators in the episode suggest that the characters in these legends were actually extraterrestrial beings and not gods or heroes.

Why are humans so different from every other species on Earth? Did we evolve from ape - or is our intelligence the result of contact with an otherworldly source? Could unexplained advances in human evolution be the work of interstellar beings? 10,000-year-old petroglyphs link our ancient ancestors with star beings. Might evidence of alien contact help unlock the mystery of the Creation of Man?