An alchemical monument that represents "Earth, Air, Fire, and Water."

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

Week-long block party becomes a competition for the best decorated street.

This semi-secret storybook hedge maze is also the oldest garden in the city.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

This colossal couch is an unlikely monument to Europe's first female Doctor of Law.

This massive library holds what was once the largest book collection in the world.

The elaborate clockwork contraptions in this Scottish gallery create small worlds of whimsy and horror.

Somewhere there is a giant who can no longer poop, but now travelers can stay inside his anus.

This unique Renaissance castle was turned into a home for Nazi occultism.

Fighting the British and making game shows for over 150 years.

When the rain falls, this drain system turns into a musical instrument.

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

Moss and stone turn this waterfall into an otherworldly liquid veil.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

Spend the night in this formerly abandoned traditional Scottish village.

This small town in the Netherlands has no roads but instead, miles of canals and over 100 bridges.

The first museum in the world devoted to sexual gadgetry.

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

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.