Cities of the Underworld Season 4 Episode release dates & where to watch

1. Mayan Apocalypse

Don Wildman explores deep below ancient ruins as he searches for clues pointing to the true fate of the once-mighty Mayan empire.

2. 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.

3. America's Unmapped Murder Tunnels

Don uses brand-new mapping technology to expose the dark and deadly uncharted spaces beneath American cities. He explores the criminal underworld below Portland, Oregon; Seattle, Washington; Chicago, Illinois; and Los Angeles, California.

4. 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.

5. 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 mighty Roman Empire.

6. Templars and The Founding Fathers

Don goes deep beneath a Knights Templar stronghold in Turkey to explore a provocative theory that may link the fabled secret society to the founding fathers of America. English

7. Secrets of the Ancient Metropolis

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

8. The Lost Aztec Colony Finale

Don follows the clues hidden underground as he searches for evidence of 10,000 Aztecs who fled Mexico and disappeared somewhere in America.