From secret prisons to escape tunnels, ancient caves to mines, Bucharest in Romania is ripe with folklore. Discover the history of its secret underworld.

The confluence of two geological forces created and continues to build the island of Iceland. They also keep the geology active with global implications. For now the massive, but retreating, glaciers are keeping the glaciers in check.

UFOs are the biggest mystery of our time and somebody - or something - seems determined to keep it that way.

Countdown To Apocalypse

Centuries ago the prophet Nostradamus had visions of the end of our modern world. Now, scholars decipher his mysterious predictions and learn of terrible tragedies and catastrophic events that threaten to annihilate global populations.

The discovery of the San Andreas Fault and efforts to understand it are described.

At the end of the 3rd century, one man rose from soldier to Emperor. Heroic Aurelian reunited the empire in just five years and became known as Restorer of the World.

From secret prisons to escape tunnels, ancient caves to mines, Bucharest in Romania is ripe with folklore. Discover the history of its secret underworld.

Could aliens have helped humans build huge ancient structures? Experts ask whether standing stones in Carnac, France, were a GPS system for ancient spacecraft.

The confluence of two geological forces created and continues to build the island of Iceland. They also keep the geology active with global implications. For now the massive, but retreating, glaciers are keeping the glaciers in check.

UFOs are the biggest mystery of our time and somebody - or something - seems determined to keep it that way.

Countdown To Apocalypse

Centuries ago the prophet Nostradamus had visions of the end of our modern world. Now, scholars decipher his mysterious predictions and learn of terrible tragedies and catastrophic events that threaten to annihilate global populations.

The discovery of the San Andreas Fault and efforts to understand it are described.

At the end of the 3rd century, one man rose from soldier to Emperor. Heroic Aurelian reunited the empire in just five years and became known as Restorer of the World.

From secret prisons to escape tunnels, ancient caves to mines, Bucharest in Romania is ripe with folklore. Discover the history of its secret underworld.

Could aliens have helped humans build huge ancient structures? Experts ask whether standing stones in Carnac, France, were a GPS system for ancient spacecraft.

The confluence of two geological forces created and continues to build the island of Iceland. They also keep the geology active with global implications. For now the massive, but retreating, glaciers are keeping the glaciers in check.

UFOs are the biggest mystery of our time and somebody - or something - seems determined to keep it that way.

Countdown To Apocalypse

Centuries ago the prophet Nostradamus had visions of the end of our modern world. Now, scholars decipher his mysterious predictions and learn of terrible tragedies and catastrophic events that threaten to annihilate global populations.

Scientists searching for evidence of past tsunamis to predict when they are likely to recur and how severe they are likely to be uncover a new phenomenon, the mega-tsunami.

As Emperor of Spain, Gaul and Britain, Constantine proved himself as a leader and changed western civilisation forever, turning the empire towards Christianity.

Cities of the Underworld

and Philadelphia: From hidden tunnels beneath Boston to the incredible waterworld under Philadelphia, the Freemasons left behind the blueprints to America's rise.

In 2008, witnesses in Needles, California, saw military helicopters carry away a glowing flying object. What was the government trying to hide? And could UFO clean-ups be common?

Ruins in Peru support legends of a sunken UFO base, and Indian texts talk of water worlds populated by humans and aliens. Could aquatic cities prove that aliens visited?