Could the darkest recesses of our planet contain important information left by our ancient ancestors? And within Earth's mysterious caves, might we find evidence of otherworldly contact?

Theorists offer compelling evidence suggesting that the ancient monolith thought to depict Egyptian pharaoh Khafra once represented an alien being.

Are we being watched by otherworldly beings? Experts make surprising discoveries as they explore the ancient past for evidence of alien overseers.

Throughout history, many of the world's greatest thinkers have helped push civilization forward with their profound insights and extraordinary abilities. But the majority of these master minds say their brilliance comes from a place they don't understand-and arrives at times they're not expecting it.

For thousands of years, in cultures throughout the world, people have practiced elaborate techniques to preserve the human body after death. The ancient Egyptians believed mummification ensured entrance into the next life.

Throughout history, incredible stories have been told of the dead rising from their graves, mummies journeying into the afterlife, and people on the brink of death mingling with deceased relatives in a celestial netherworld. Are they simply legends--or could some of these stories actually be true?

There are those who believe that embedded in our most sacred religious texts, as well as in the design and location of ancient monuments, are secret messages that may reveal the purpose behind our very existence.

It is a story told in more than twelve hundred cultures around the world: the gods sent a great flood to wipe out humanity for its disobedient and wicked ways.

The Civil War nearly destroyed the great experiment known as the United States of America, but is it possible that the preservation of the republic was influenced by extraterrestrial beings?

Stories of civilisations large and small disappearing without a trace can be found throughout history and across the globe.

Ancient Astronaut theorists have long proposed that extraterrestrials played a pivotal role in our past, and some believe they continue to keep a careful watch over the progress of mankind.

While scholars, scientists and governments have now openly joined the hunt for life beyond Earth, the search for alien life has been underway for decades. In 1947, strange events forced high-level members in the US government to become alien hunters.