From the swords of barbarian hordes to the guns of the Spanish Empire, Europe's darkest days lasted 1,000 years. After the fall of the Roman Empire, Europe was plunged into chaos for centuries, with mass bloodshed, rampant disease, and vicious carnage regularly raging through the streets. But below them, another world was carved out to keep the people alive...and enemies on their toes. From the immense quarries of a secret society to Templar torture chambers and the tunnels of medieval "ghost knights," Don Wildman tracks down the darkest secrets of the Dark Continent, buried deep below Europe's streets. For more info, please visit http://www.history.com/cities-of-the-underworld
