Underground

Spectacular mineral formations fill these caves, which have been used for everything from smoking meat to stashing illicit liquor.

A network of underground water channels that dates back to the Middle Ages.

Nine caves filled with recently-discovered archaeological finds under the houses and the streets of the most ancient district of an old town.

The oldest known metal-mining site in England dates back to the Bronze Age.

Walk into an underground archeological dig, the site of the Roman Forum that was once the center of Valencia.

One of the few cold geysers in Europe, its eruptions are powered by carbon dioxide.

A sprawling network of century-old subterranean catacombs lies beneath a nondescript suburban home.

Underneath downtown Lincoln resides a network of caves that was also the city's first brewery.

A special area of the National Archaeological Museum of Naples is located inside a metro station.

Fortifications built for a Soviet invasion that never came now sit abandoned in a losing battle against nature.

An off-the-beaten path cave with an underground lake.

This subterranean town of over 50 dwellings lies thirty feet beneath the Earth's surface.