This 17th-century passageway is home to numerous bookshops, a witch legend, and the oldest pizzeria in the world.

The relics of dozens of martyrs are stored in a single chapel.

The Neapolitan Cult of the Dead still cares for the skulls at this mini-Fontanelle.

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

These ruins of a Phoenician sanctuary in Sicily have a dark history.

Tourists to the mountaintop Sicilian town often overlook its ancient fortifications.

Built on a medieval synagogue, this church has a burial crypt, tunnel system, and Jewish ritual bath hiding deep underneath.

This generously endowed statue once stood guard outside a Roman home.

Occupied for six centuries by Franciscan Order nuns, this monastery is an amazing ode to Catalán Gothic architecture.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

This cafe offers a curated collection of treats and tipples made by monks and nuns.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

Dine on Hungarian-Jewish dishes at this multigenerational, family-run institution.

Legions of Roman soldiers bathed in this ancient spa complex under a Budapest transit station.

Once the home of a hermetic monk, this cave now houses a small church.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

Dine on food tied to Viking history and legend at this subterranean Stockholm spot.

An illuminated manuscript comprising the life's work of a lone monk, inexplicably decorated with a portrait of Satan himself.

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

A museum of magic with a Sadist past.

A giant white horse drawn on an English hillside may not have been intended to be a horse at all.

Home to Alan Turing, the cracking of the Enigma code, and Captain Ridley's shooting party.