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

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

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

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

This funky former tobacco factory is one of the most striking examples of Madrid's cultural diversity.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

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.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

Macabre astrological automaton clock dating to the late 1400s.

Relive a Polish uprising via an enormous, century-old cyclorama.

This open-air museum was originally a World War II testing ground for German missiles and rockets.

A striking public sculpture representing the period of martial law in Communist Poland.

These massive moving sand dunes have swallowed an entire village and are still on the run.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

The site of the first battle of World War II.

Communism's topsy-turvy effect on Poland has been brought to life in this wacky tourist trap.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.