The oldest residential street in Europe also features an optical illusion.

The tallest city hall in the world offers an excellent bento box.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

Ride a boat through this magnificent underground world, which now doubles as a theater.

This medieval hilltop village was abandoned at the end of the 19th century, after existing for more than 500 years.

The ruins of this medieval castle on a foggy hill tell the story of a once-mighty empire.

According to this bar, God gave an “11th commandment” to Antwerp: Thou shalt drink beer.

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

The oldest continuously operating pharmacy in Europe.

The medieval woodcut-style artwork chronicles life in medieval London.

A medieval stronghold rising over the ruins of ancient Roman villas along Rome's southern coast.

This precariously perched fortress was once ruled by a crow-worshipping baron.

This fresco-covered medieval monastery hangs from the side of a steep cliff.

Horrifically creative torture devices and shame punishments line the walls of this chilling museum.

Inside this former medieval prison is a collection of objects designed to inflict unbelievable pain and suffering on the human body and mind.

This open-air mosaic gallery honoring an English artist took hundreds of volunteers more than seven years to create.

Double spiral staircases are not unheard of, but they are very rare.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A spiral staircase twists to the top of this unusual Czech lookout tower.

What's a diner from the 1939 World's Fair doing in a remote Utah mountain town?

Eat like pre-Columbian Native Americans in this New Mexico restaurant within the Indian Pueblo Cultural Center.

A curious memento mori hangs in the magnificent Cathedral of Segovia.

A breathtaking and biodiverse wilderness in the mountain setting of Ernest Hemingway's "For Whom the Bell Tolls."

A magnificent, long-abandoned castle built in the wake of the reconquest of Spain.