A cheeky architectural easter egg.

Be(w)ar(e) the moat around this historic Czech castle.

The soulless eyes of 82 bronze children stare on forever in remembrance of a horrifying World War II massacre.

This unusually shaped mountaintop tower looks like a UFO floating over the city.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

Europe's largest natural bridge has a 19th century royal chateau built into its side.

Two monstrous faces loom over a village in Czechia.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

A church of bones, decorated with 40,000 human skeletons.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

Roughly 17 million letters to Santa have found their way to this Arctic Circle post office.

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

A hidden church in a hidden courtyard tells the story of the Miracle of Amsterdam.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

Amsterdam's former hotspot for public executions and dissections.

A fearsome dragon clings to a corner of Munich's city hall.

This amazing piece of modern art honors the hundreds of fishermen killed during Cambrils' "year of misfortunes."

Long tunnels run under the ancient chariot racing circuit to the tower.

One of the few surviving street funiculars in the world.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

A fairytale island floats in the middle of Italy's little-known Lake Orta.

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

A centuries-old forgotten underworld lies beneath Malta.