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 the gunfight 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.

Might the tools and technology of ancient builders have come from distant galaxies? Evidence suggests that an ancient mountaintop fortress in Peru was constructed with laser-like tools... temples at Vijayanagara India were built to harness cosmic energy... and an acoustic chamber in Malta enabled interplanetary communication. If the ancient builders did use advanced technology, could it prove that aliens visited Earth thousands of years ago?

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... Gunpowder 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 suicide. 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?

What is the meaning behind secret messages found throughout Washington, D.C.? Did America's Founding Fathers know something about ancient aliens that the general public did not? And if so, could this knowledge have been incorporated into the symbols, architecture, and even the founding documents of the United States of America?

Mass suicides. Human sacrifices. Unholy rituals. Throughout history, people have claimed to have otherworldly knowledge, and have led followers to commit horrific acts of violence. Are they con men? Are they insane? Or might the voices in their heads really be of an extraterrestrial origin? And if so, did they simply misinterpret the messages they received? Or might there be extraterrestrials with a sinister agenda?

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?

Zombies rising from their graves... Blood sucking vampires damned for all eternity... and humans trapped in a life and death struggle between heaven and hell. For thousands of years, mankind has told tales of encounters with strange, soulless creatures. Are these beliefs merely manmade fabrications - or could there be extraterrestrial origins in earthly encounters with the undead?

Superhuman strength... Supernatural powers... And the awesome ability to fly. Throughout history, mankind has told incredible tales of gods with extraordinary powers. But are these accounts merely tall tales, or could they be based on factual events? If mythical gods really did exist, were they, as ancient astronaut theorists believe, extraterrestrial beings? And could this help to explain the enduring popularity of gods, titans and other so-called "super-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?