For billions across the globe, Jerusalem is considered ground zero for Armageddon. While most of the world's population considers it a holy land, it's also one of the bloodiest cities the world has ever known. From a hidden occult city built by the Knights Templar to the hiding place for the Dead Sea Scrolls, the evidence of the apocalypse is buried all over the holy city.

See a Vietnam that you've never seen before. During the Vietnam War the media flooded the world with images of soldiers and jungles. What wasn't seen were the tunnels, caves and passageways.

Tokyo, Japan is a city straight out of the future, above ground and below. Go beneath the busy streets to see the latest technology that will save the city from the many natural disasters ready to strike. From there go back in time to World War II to see how Hiroshima's underground offered protection from the most powerful bombs.

Dublin, Ireland is much more than a city full of pubs and pints. Burial tombs, defense tunnels, and mysterious burial crypts line the underground below the rolling hills.

Prague is a city cloaked in mystery, with an underground to match. Medieval castles line the streets & dark dungeons lie deep below them. From quarries where Hitler may have stored his secret weapons to mines that doubled as Communist slave camps, Prague has surprising stories to tell.

Visit the center of Mayan civilization. Hundreds of ruins scatter the landscape & reveal clues to bloody rituals, advanced architecture & belief in an unforgiving underworld of Mayan gods.

Chicago was once a playground for mobsters and corrupt politicians. It wouldn't be the third largest city in the U.S. today if it weren't for the shady dealings that went on just beneath its streets.

The ancient world was shaped by people who believed they foresaw the will of God. Jerusalem is at the heart of all their fiery prophecies. From bloody wars to the birth of saviors, Jerusalem has been at the center of prophetic revelations.

New York City is the biggest city in the country, but it's got some dark secrets. Founded by covert groups, overrun with gangs and mob bosses, and ruled by secret societies, this is the true foundation of the city that never sleeps.

Learn about what goes on underneath the streets of our nation's capital.

Stalin's terrifying legacy: a subterranean web is so vast modern Moscow is in danger of caving in.

Learn how New Orleans is rebuilding itself for the next "big one."

Deep within the former Soviet Union lays a classified, subterranean world of Cold War secrets.