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

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.

Istanbul is undoubtedly one of the most dynamic and exotic cities in the world. Once the capital city of three of the world's most powerful empires--The Roman, Byzantine, and Ottoman--its strategic location made it the perfect spot for empires to rise, fall...and rise again. Today Istanbul's residents are walking on top of remnants of these fallen civilizations...literally. Taxis drive over parts of Constantine's Lost Great Palace; children play on cobblestone streets concealing a massive Byzantine dungeon; a high school sits on a 3rd century wall leading to the bowels of a 100,000 seat ancient Roman Hippodrome; and basements of old Ottoman homes lead to subterranean tunnels and secret cisterns. Join host Eric Geller as he leaves the buzz of the city streets behind and follows the pull of the past. Teamed with leading archeologists and experts, Eric peels back the layers of the past--to reveal a hidden history that hasn't seen the light of day for ages.

What was the secret to the success of ancient Rome? Aqueducts, underground neighborhoods, and one of the oldest sewer systems reveal many secrets. The largest and most influential empire in history leaves clues to her greatness under nearly every street. Search subterranean locales for proof that ancient Roman design inspired many modern engineering marvels. Join host Eric Geller as he exposes city upon city and the technological marvels that allowed it.

Rome is a city where the past meets the present on every corner. A secret cult practiced right next to the Circus Maximus, and their temple still remains beneath the street. The famous Piazza Navona sits on top of Domitian's Stadium. Pieces of Trajan's Basilica can be found under a gallery owned by fashion dynasty Fendi. Rome's underground is filled with evidence of life during the Empire. Join host Eric Geller as he discovers what life was like during Nero's tyranny and Augustus' reforms and reveals the technological marvels that allowed the construction of one city upon another--literally.

Beneath the hustle and bustle of Paris streets is a world of snaking quarries, hidden catacombs, and mushroom-harvesting tunnels. Even Paris' 10.5 million residents have no idea they live on top of nearly 20 centuries of history carved into the limestone foundation below. From its Gallic beginnings to the Roman foundations of Lutetia, today's Paris may be one of the world's most sophisticated cities above the ground--but below ground it's a different story. Join host Eric Geller as he reveals the secrets beneath Paris and the Notre Dame church and what they reveal about a 2,000 year old civilization that rests underneath it.

For thousands of years London has been among the most powerful cities in the world. However, below the busy streets and marketplaces another city hides--a city of Roman baths, secret crypts, lost rivers and indestructible bunkers that could hold up to 8,000 people. Join host Eric Geller as he reveals the subterranean secrets found below London's most famous landmarks and even finds Winston Churchill's hidden war rooms.

Ethiopia is home to some of the oldest settlements in the world. This cradle of mankind is a country born from legend and shrouded in mystery. An ancient home to both Jews and Muslims, Ethiopia is also the world's second oldest Christian nation. But if you were a Christian during ancient times, and if you wanted to stay alive, the only place to practice your faith was underground. From underground engineering marvels to remote, cliff-hanging caves, Ethiopia's isolated churches allowed Christianity to evolve in ways found nowhere else in the world. From tombs of vanished emperors and subterranean cathedrals where orthodox priests have been worshipping for thousands of years, to the buried Palace of the Queen of Sheba and the possible resting place of the Ark of the Covenant, clues to Ethiopia's lost legends and tribes are littered right here...in the African underground.