Hidden Beneath the Cities

Uncover a vast underground city in Turkey that served as a refuge for Christians and Jews. Investigate a mysterious chalk chamber in England, visit a secret Etruscan complex beneath an Italian wine cellar, and map an ancient tunnel network in Iran.

Marvel at the crystal caves and underground chapels of Poland's Wieliczka salt mine. Tour a secret Cold War bunker in England, unearth a 3,400-year-old royal settlement in Egypt, and try to solve the mystery of China's enigmatic Longyou Caves.

Investigate a tomb in Naples that may contain a prince who inspired the legend of Dracula. Read the desperate letters of Jewish rebels hidden in an Israeli cave, tour a 6,000-year-old labyrinth in Malta, and see the oldest human burial in Africa.

Crawl through a notorious brick-lined tunnel system in a historic Florida neighbourhood. Open a window into the lives of elite Greek families in Naples, explore a three-story underground city in Iran, and find 2nd-century barracks buried in Rome.

Explore a labyrinth built beneath Washington, D.C., by an eccentric entomologist. Admire a fresco-filled Roman mausoleum, spot intricate chambers carved into Colombia's volcanic rock, and see a sprawling network of hand-dug tunnels in Liverpool.

Walk the service tunnels hidden beneath Emperor Hadrian's lavish villa in Italy. Uncover a chilling mass grave from the Thirty Years' War in Germany, find the foundations of a Roman basilica in London, and glimpse Neolithic life on a Danish island.

Examine a Revolutionary War-era ship found in the rubble of the World Trade Center. Uncover a mass grave of Viking settlers in Oxford, visit the resistance bunkers of the Warsaw Ghetto Uprising, and tour a necropolis full of burial jars in Corsica.

Dig beneath the Treasury in Petra, Jordan, to find a sealed tomb containing 12 skeletons; unearth a hoard of coins hidden during a Scottish massacre, question the purpose of an empty grave in Peru, and inspect a Bronze Age leader's coffin in England.

Discovering a massive underground chamber hiding under the Seoul subway; visiting a medieval knight's limestone tomb in Poland; examining Roman ruins beneath a church in England; pondering the identity of a 10-million-year-old fossil in Los Angeles.

Visit a strange wood-lined tunnel beneath a Copenhagen train station. Locate one of North America's earliest schools for Black children in Virginia, excavate a warrior cemetery in Finland, and unearth a women-only burial plot beneath a Welsh castle.