All over the world stand ancient structures so massive, precise, and baffling that they seem impossible for not just their time, but ours as well. From colossal walls and giant stone tombs to temples carved from solid rock, how did ancient civilizations achieve feats of engineering that still defy modern understanding?

Dreams have inspired humanity for thousands of years and in all this time, we have yet to answer one fundamental question: What is the purpose of dreams? From nightmares linked to unexplained deaths and more.

Throughout history, catastrophic disasters have reshaped civilizations -- yet some events defy all scientific expectations.

Africa remains one of the most mysterious continents on Earth. From lost cities buried beneath shifting sands, to the elusive tomb of history's most mighty queen, what secrets lie hidden throughout Africa's vast landscape?

The human mind is home to all our thoughts, hopes, dreams, and memories.

An exploration of strange and inexplicable mysteries; contributions from scientists, historians and witnesses as they seek to shed light on how the impossible can happen.

Every year, people risk their lives to enter places the world has marked off-limits. What is it about the world’s most dangerous places that makes them impossible to resist?

From demonic possession and cursed homes to battlefield apparitions and ancient pacts with the Devil, history is filled with chilling accounts of supernatural forces said to be working against humanity. Are these terrifying encounters simply the product of fear and belief… or could they point to a hidden war between good and evil-one that continues to this day?

Throughout history, governments have carried out top secret projects that defy belief-from experimental aircraft and staged illusions to covert experiments that crossed ethical boundaries. Hidden from the public and revealed only years later, these operations raise a chilling question: if these programs were real… what else might still be happening in secret today?

Dinosaurs have fascinated scientists for nearly two centuries, and in all that time, we have yet to answer even the most basic questions about how these animals lived, how they died, and what became of them. From an extinction event whose cause scientists to actively debate, to ancient dragon legends some researchers trace directly to fossil discoveries, to genetic technologies now being used to bring extinct creatures back to life. Content expanded.

Five centuries after the fall of the Aztec Empire, new discoveries are revealing that this lost civilization may have been far more sophisticated-and far stranger-than history has long suggested.

For centuries, certain objects have been deemed to heal the sick, summon spirits, legitimize kings, curse their owners, and even alter the fate of nations.

Across the planet are places where nature behaves in ways that seem to defy explanation. Forests where people vanish, deserts where signals fail, caves filled with toxic air and mountains no one dares to climb.

Throughout history, people have feared that ancient curses can bring misfortune, madness, and even death to those who defy them.

An exploration of strange and inexplicable mysteries. Contributions from scientists, historians and witnesses as they seek to shed light on how the impossible can happen.