Naples is a time capsule of ancient life, with banks, bakeries and even Nero's famous stage hidden under the streets and in the caverns of Vesuvius.

An alternative world thrives in the shadows of this capital 'city of lights'. Host Eric Geller has special access to this dark underworld, where both the secrets of the living and the sins of the dead are revealed.

Budapest sits on top of an ancient secret. Follow Eric Geller as he uncovers a top secret WWII hospital and finds the source of the boiling healing water used by the Romans and the Turks in the caves beneath Budapest.

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

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

Host Eric Geller travels through the dark and damp recesses of Berlin's secret bunkers. Engineered by the Nazis during WWII, their dark past is revealed.

From Roman baths, secret crypts, lost rivers and even Winston Churchill's hidden war rooms, London's underground world has a plethora of stories to tell.

What's at the heart of the Big Apple? Explore a tangle of engineering, history and secrets that make up a dark urban underworld labyrinth. It's the city that never sleeps!

Host Eric Geller discovers what life was like during Emperor Nero's tyrannical reign and Augustus's reforms by peeling back the hidden history of Rome.

Beneath the modern city streets, ancient underground neighbourhoods and sewerage systems reveal the technological marvels that helped advance an empire.

From plague victims being buried alive to body snatchers, illegal distilleries and castle dungeons, Edinburgh's underground world has a myriad of stories to tell.

The castles and dungeons of the Hittites are hidden beneath the sandy lunar landscape of Cappadocia. Why did this ancient empire fall?

Slave tunnels, gambling dens and opium runners: welcome to the dark, 100 year-old underworld history of Portland, Oregon, famous for being a city full of vice.

Istanbul is one of the most dynamic and exotic cities in the world. It's where east meets west. Teamed with leading archeologists and experts, come along as we peels back the layers of the past.

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

We go beneath the streets of Japan to see the latest technology that saves the city from the many natural disasters ready to strike. Head back in time to World War II to see how Hiroshima's underground offered protection from the most powerful bombs.

Join host Don Wildman as he reveals the technological marvels that allowed the construction of Prague, a city cloaked in mystery, with an underground to match.

Join host Don Wildman as he discovers the massive CuChi tunnel system that gave soldiers the upper hand to the super-bunkers and secret caves used as shelters.

Host Don Wildman has special access to a sacred stone said to keep the world from ultimate chaos, and finds evidence of John the Baptist's apocalyptic sermons. He heads into a vast underground that ignited the violent visions of the end of the world.

From vice dens and top-secret railroad lines to sunken shipwrecks and the spark that created the A-Bomb, Don Wildman unearths the true history of the Windy City.

Host Don Wildman ducks beneath the jungles of Belize to uncover burial tombs, sacrificial altars, ritualistic caves and the literal entrances to the Mayan underworld.

Join Don Wildman as he uncovers an ancient escape route and the birthplace of Jesus. He sets out to find the truth behind Jerusalem's most mysterious and enduring prophecies, the people who foretold them and what was left underground.

Don Wildman heads beneath the skyscrapers and street vendors into a New York that few have ever seen. From a hidden Freemason tunnel and secret world of the Sandhogs, we're uncovering the secret societies that built New York.

Moscow is a city known for its ruthless leaders and abundant secrets. Below its crowded streets lie the reminders of its war-torn past � and Stalin's terrifying legacy.

During the Cold War, the Ukraine once contained the world's third largest nuclear arsenal in a secret subterranean lair. Discover the Iron Curtain's secret underworld.

When Hurricane Katrina hit, parts of New Orleans were devastated. Do the answers to protecting the city from global warming lie in its historical underworld?

Don goes deep beneath the great lakes and explores flooded caves as he searches for evidence of a mysterious, cave-dwelling society that may have been the first people to reach America.

Don goes deep beneath the great lakes and explores flooded caves as he searches for evidence of a mysterious, cave-dwelling society that may have been the first people to reach America.

Don explores top-secret military and government tunnels and looks into classified technology that could be used to build entire cities right under our feet.

Don uses brand new mapping technology to expose the dark and deadly uncharted spaces beneath American cities.

Right beneath our feet, there are cities hidden by time that may hold clues that could rewrite history. In this series, Don Wildman travels to the furthest and deepest reaches of the globe, exploring mysteries buried deep underground.

Don explores the massive underground cities in the mountains of Turkey that may have been home to the first civilisation on Earth.