In a city that boasts four separate inclined cable railways, this is one of the busiest funicular lines in the world.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

Skulls from the plague of 1656 and World War II bombings are united by a cult dedicated to caring for the ancient dead.

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

These "anatomical machines" are only one of the many strange items in this Italian crypt.

Dug as a secret royal escape route, the tunnel became a wartime bomb shelter and dumping ground for vintage cars.