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.
S1 E2: Catacombs of Death: Paris
S1 E3: City of Caves: Budapest
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.
S1 E4: Dracula's Underground: Bucharest
From secret prisons to escape tunnels, ancient caves to mines, Bucharest in Romania is ripe with folklore. Discover the history of its secret underworld.
S1 E5: Freemason's Underground: Boston...
and Philadelphia: From hidden tunnels beneath Boston to the incredible waterworld under Philadelphia, the Freemasons left behind the blueprints to America's rise.
S1 E6: Hitler's Underground Lair: Berlin
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.
S1 E7: London's Lost Cities
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.
S1 E8: New York
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!
S1 E9: Rome's Hidden Empire
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.
S1 E10: Rome: The Rise
Beneath the modern city streets, ancient underground neighbourhoods and sewerage systems reveal the technological marvels that helped advance an empire.
S1 E11: Scotland's Sin City
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.
S1 E12: Secret Pagan Underground: Cappadocia
The castles and dungeons of the Hittites are hidden beneath the sandy lunar landscape of Cappadocia. Why did this ancient empire fall?
S1 E13: Underground Bootleggers: Portland
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.
S1 E1: Beneath Vesuvius: Naples
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.
S4 E1: Mayan Apocalypse
S4 E2: America's Ancient Ancestors
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.
S4 E3: The Pirate Queen's Lair
Don explores newly discovered ruins and caves in Croatia as he uncovers the true story of a formidable queen who dared to defy the powerful Roman Empire.
S4 E4: America's Military Underground
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.
S4 E5: Murder Tunnels
Don uses brand new mapping technology to expose the dark and deadly uncharted spaces beneath American cities.
S4 E6: Secrets of The Ancient Metropolis
Don explores the massive underground cities in the mountains of Turkey that may have been home to the first civilisation on Earth.
S4 E7: The Lost Aztec Colony
Don follows the clues hidden underground as he searches for evidence of 10,000 Aztecs who fled Mexico and disappeared somewhere in America.
S4 E8: Secrets of The Ancient Metropolis