The Pantheon is a 2,000-year-old temple with a dark secret; today, using cutting-edge archaeological methods and brand-new evidence, experts look beneath the streets of Rome to find out why it was built and how it survived so long.

According to legend, the ancient Roman city of Hierapolis hides a secret portal to the underworld beneath its streets; armed with pioneering technology, archaeologists gain rare access to investigate the deadly truth behind these hellish myths.

Venice was once a fearsome superpower home to secrets, wealth, and treachery; today, scientists use pioneering acoustic imaging technology to discover the city's ancient foundations and reveal how it's still standing.

The Tower of London is a centuries-old castle shrouded in a grisly past.

A prehistoric structure could reveal mysteries to the Bronze Age.

The secrets of the world's oldest sunken city are lost to history, but hi-tech underwater archaeology answers questions that books cannot; experts explore sunken ruins and reveal new discoveries about one of the first great empires.

Experts decode an Egyptian pyramid constructed as if it floats on water.

Deep in the Iraqi desert, the world's only ziggurat towers over the remains of the first civilization ever known in human history; armed with pioneering satellite imagery, experts investigate the dark mysteries behind this massive, ancient structure.