Every half hour the eye-rolling clock face sticks out its tongue to mock the good citizens of Koblenz.

This fountain of a little boy that spits on passersby at erratic intervals is a town icon.

The 20-mile causeway that separates the Netherlands from the sea.

The last of Amsterdam's original sea level markers remaining in place.

Lumps of significant stone from around the world surround a flaming monument for peace.

This enormous storm barrier is one of the largest moving structures on Earth, with each arm taller than the Washington Monument.

This Dutch windmill has its roots in an American invention.

This bird-loving brewery is situated in an old municipal bathhouse, nestled beside a 300-year-old windmill.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

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

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

Inside this metro station is a section of the city's former medieval fortification.

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

The former home of a mad diplomat is said to still be marked in bloody, arcane scrawls.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

Museum preserving torture methods from the past.

Amsterdam's Red Light District leaves little to the imagination.

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

This unattributed sculpture in Amsterdam is hiding in plain sight.

This tiny island featuring 9th-century Viking ruins is only accessible at low tide.

The most visited, and possibly most controversial, museum in Germany.

The prototype for all Nazi concentration camps.

At 929 pounds and 26 feet tall, this stainless steel fork can only be used by the likes of King Kong.

Lucerne's central prison was converted into a tourist hotel with a bare minimum of changes.