1: Cities of the Underworld Istanbul

2: Cities of the Underworld Scotland's Sin City

3: Cities of the Underworld Hitler's Underground Lair

4: Cities of the Underworld Rome's Hidden Empire

5: Cities of the Underworld Catacombs of Death

6: Cities of the Underworld City of Caves

7: Cities of the Underworld New York

8: Cities of the Underworld London's Lost Cities

9: Cities of the Underworld Beneath Vesuvius

10: Cities of the Underworld Freemason Underground

11: Cities of the Underworld Dracula's Underground

12: Cities of the Underworld Secret Pagan Underground

13: Cities of the Underworld Underground Bootleggers

14: Cities of the Underworld Rome: The Rise