The medieval castle built as headquarters for the Pope's secretive Knights Templar.

A unique seaside cave where Aleister Crowley faked his own death.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

Houses are tucked between, on, and underneath giant boulders.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

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

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

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.

The celebrated eyesore created by starry-eyed sweethearts.

What looks like a normal building is really a hollow facade hiding a subway vent.

This bridge was constructed from the rubble of the infamous Bastille.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

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

France's most famous cemetery, with some of its most curious tombs.

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

A towering monument in Spain has proven to be more labor-intensive than initially planned.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

Commonly acknowledged as the only public monument to the Devil himself.

An ancient Egyptian temple in the middle of Madrid, Spain.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.