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

One of the largest Roman settlements in Portugal.

The "Little Ones," show Portugal in full miniature splendor.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

Elaborate tile work in this railway station tells the story of Portugal.

Ancient catacombs form the foundation for this Rococo orgy of a church.

Picturesque intersection of witchcraft and ancient Christianity.

A stunning 18th-century site where pilgrims ascend by a series of punishing stairs only to return via funicular.

The oldest Roman lighthouse still in use.

Thanks to an acoustic anomaly, this unassuming stone bench has heard one hundred years of secrets.

Two towns are linked by an engineering marvel masquerading as a boring suspension bridge.

This tiny river island switches sovereignty every six months as part of a rare, centuries-old agreement.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

For one day every month Barcelona's Estació de França transforms into a market for model trains.

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

A once-secret library of Freemason history in Catalonia.

18th century anatomical amphitheater of the Royal College of Surgery of Barcelona.

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

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the 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.

One of Europe's largest supercomputers is housed inside of a disused chapel.

This imposing modern citadel started out as a home renovation project.

A gravity-defying "devil's bridge" that has a surprising architectural feature for its stability.