Giant eggs, walls of bread, and nightmare surreality mark the largest collection of works by Salvador Dalí.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

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

Gaze upon chocolate sculptures depicting everything from chariot races to Gaudí's famous church at this shrine to sweets.

Bask in the 19th century grandeur of an eccentric Freemason millionaire's private gardens.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

Mountain where Jesus was first tempted by the Devil.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

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

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

A psychedelic labyrinth on the San Francisco bay.

A huge musical instrument played by the ocean.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

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

The last remnants of a massive medieval wall that once encompassed the city of Berlin.

The final resting place of many of Germany's most famous communists.

A restaurant and observation deck built in a unique broadcasting antenna.

Floating swimming pool within a moored vessel.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

Art and a pun, all in one.

Started as a kitchen garden, now the second largest botanical garden in the world.