Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

If you ever wanted to touch a medieval mercenary’s three testicles, look no further.

This peculiar Italian elevator runs both horizontally and vertically.

Once home to one of the oldest banks in the world, this building is also where Marco Polo's famous travelogue was written.

This grisly effigy displays an early Christian martyr who was skinned alive and beheaded.

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

The secret medieval communication system will whisk your words above the noise of the crowd.

Small on the outside, big on the inside, this church is an astonishing act of visual deception.

Built in the 1920s, this co-op in the Bronx feels more like an Italian villa than a typical New York apartment building.

The longest step street in the city.

Rome’s legendary peephole vista is also a former Crusader stronghold.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

One of the most breathtaking railways in Europe also takes one of the steepest climbs, from fjord to mountain plateau.

The ancient latrines of the Greeks, in all their public glory.

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

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

Built by a king and rebuilt by an emperor, this aqueduct transported water for 1,200 years to this ancient Mediterranean hub.

Venice's island of the dead.

An ancient fortification lives on in this Chinese city.

Once the site of the Hawaiian monarchy, this building was originally designed as a palace.

Elevated freight railway turned wildly successful urban park.

What appears to be an ancient Roman temple is actually a Catholic church.

Three floors of musical instruments coming from all corners of the world and hundreds of years of musical history.

Christ's blood allegedly preserved in a Belgian town.