The White House has consistently denied having any knowledge of alien craft visiting Earth, but presidential encounters with UFOs and other strange phenomena can be found going all the way back to George Washington. Is it possible that extraterrestrials have been monitoring–and even influencing–America's presidents'

UFO witnesses have reported a wide variety of objects in Earth's skies--and not only in modern times, but for centuries. What might we learn from examining their shapes, sizes, and the way they maneuver' Could they offer important clues about other intelligent life in our galaxy'

Nestled within a remote valley in Utah, is a ranch that some believe is a hotbed of strange, inexplicable phenomena including terrifying creatures, paranormal apparitions and lights in the sky. Could the bizarre activity have a connection to an alien entity known as the Skinwalker'

Accounts of creatures that can shapeshift from one form into another can be found throughout history. Could striking similarities between the ancient stories and modern-day alien abduction accounts reveal that shapeshifters are real and have come to Earth from another world'

In the Mojave Desert, there is a structure built to bestow everlasting life--and according to the architect, the blueprint was provided by an extraterrestrial visitor. Known as the Integratron, it has been called a work of genius, but could it actually provide the key to immortality'

In numerous ancient cultures throughout the world, stories were told of ancestors that came to Earth from the Pleiades star cluster. Could new scientific findings reveal that humankind's true origins lie not on Earth… but 400 light years away'

Shocking new evidence reveals that advanced civilizations might have existed on Earth tens of thousands of years ago. Is it possible that a technologically advanced society thrived on Earth then' And did they leave behind a record that they lived alongside extraterrestrial beings'

From Egypt to Easter Island, towering figures built by ancient man stand watch over the Earth. Are these stone giants simply a testament to humanity's past or could they depict visitors from another world' And do they serve a technological purpose that modern man is just now unlocking'

The allegations that the U.S. government is plotting with space aliens.

Chile boasts the highest number of annual UFO sightings of any nation on Earth. Now, incredible new footage of a strange craft–captured by a Navy helicopter–has even the Chilean government asking if alien visitors are drawn to this part of the world. Is there a connection to the more than 5,000 ancient geoglyphs found into Chile's Atacama Desert'

In 1947 the U.S. military collected the debris of what they claimed was a crashed weather balloon outside of Roswell, New Mexico. But new evidence may prove the conspiracy theorists right--that the wreckage actually belonged to an extraterrestrial spacecraft. If true, could remnants of it still exist that the recovery teams overlooked'

Giorgio Tsoukalos and David Childress explore the mysterious chain of manmade islets in Micronesia's Nan Madol. Built from a staggering 250 million tons of volcanic rock, could the local legends be true--that strange visitors floated the massive rocks through the air? And might the site's powerful magnetic anomalies be the result of extraterrestrial technology?