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

A beautifully eclectic mix of architectural styles.

The footprint of a frustrated devil in Munich's Cathedral.

Two stone columns flank the grand Venice square, but there were supposed to be three.

The oldest of Venice's plague quarantine stations, designed to keep the medieval city safe from disease.

Those who own or stay at this 500-year-old, allegedly cursed house often meet terrible fates.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

The world's brightest bioluminescent bay.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

An ever-evolving wall of graffiti art off East Liberty Street.

The city is full of whimsical portals to another world.

Less a museum than a bizarre fantasy world created by artists and engineers.

The fifth-longest natural arch in the world, and the longest outside China.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

Go inside to really appreciate this 500-year-old technological masterpiece.

Museum preserving torture methods from the past.

A fantastical 13th-century fortification sandwiched by a modern hotel in central Brussels.

A little sculpture with a large wardrobe.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

Climb inside an iron crystal magnified 165 billion times its normal size.

Go surfing on this urban wave, "hacked" by local surfers.

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