Famed for its pie, this eatery has a hidden tunnel that allowed Catholics to secretly walk to church during the Reformation.

Seven mini rowhouses fill the gap between 54 and 70 Westerstraat.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

A floating cat sanctuary on an Amsterdam canal.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

A saintly relic hidden in a Prague church basement.

This charming wooden church was disassembled and moved not once but twice before settling in this Prague garden.

Street artists transformed an abandoned air vent into the beloved Star Wars robot.

Buried five stories underground, this Soviet bunker is packed with gas masks and Cold War paraphernalia.

A collection of anatomical samples from one of the first anthropologists to suggest that humans reached North America by crossing the Bering Strait.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

The hidden lair of an alchemist rediscovered in a 2002 flood.

Two stunning 17th-century libraries and a cabinet of curiosities.

A prison tower–like edifice honoring a beloved local benefactor.

A curious urban windmill once owned by a renowned British mathematical physicist.

The English Civil War began right here in 1642.

When it came to designing his own small office building, the eccentric architect wasn't afraid to show the world what he could do.

When the public was consulted about a new piece of street art, they naturally asked for an enormous metal dragon.

A labyrinthine underworld of tunnels and caverns hides beneath the city.

Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

A quartet of brightly colored mythical beasts stand sentry at this gateway.

This 15th-century structure had a long, tortuous journey to its current location.