Cities of the Underworld (2007)

Season 3: Episode 6

After the fall of the Roman Empire, Europe was plunged into chaos for centuries, with vicious carnage and rampant disease regularly raging through the streets. However, below the streets was another world designed to keep the people alive and the enemy guessing. Join host Don Wildman as he uncovers immense quarries of a secret society, Templar torture chambers and the tunnels of medieval "ghost knights."