Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

A former steam-powered mill from the 1800s is now an industrial park with a giant steel dragon slide.

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.

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

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

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

A lush indoor jungle fills this bustling Madrid transportation hub.

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

A sculpture park that takes the use of clay to a whole new level.

Ha Long Bay's "Cave of Surprises" houses a popular phallic rock formation.

Time-frozen department store of dangerous and dusty relics.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

A forest of phallic offerings found in a quiet corner of a hotel car park.

A phallic shrine to a princess goddess in Krabi, Thailand.

This Bangkok high-rise looks like a rudimentary LEGO elephant.

The world's oldest known salt mine.

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

A focal point of the Cuban government, this city square features one of the most iconic images in the country.

The oldest cemetery of modern-day Athens blends the modern and ancient worlds.