San Gennaro, the patron saint of Naples, greets pedestrians between these narrow city streets.

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

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

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

This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

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

Tiny museum with unusual specimens.

This deconsecrated church has seen many uses, from a tobacco storehouse to a cinema.

Two stone columns flank the grand Venice square, but there were supposed to be three.

In the past, Renaissance sex workers were encouraged to entice customers on this bridge.

Go inside to really appreciate this 500-year-old technological masterpiece.

An incredible menagerie of more than 3 million taxidermied animals at the oldest science museum in Europe.

This museum is rotten with a century of wax medical deformities.

The largest and most famous wax anatomical collection anywhere in the world.

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

The vast, legendary catacombs hold secrets much stranger than stacked bones.