Rome's semi-secret peephole vista is also a former Crusader stronghold.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

On the wall of this medieval walkway, a symbol of the Spanish Inquisition.

A statue of a boy looks up at where the famous rival to the Leaning Tower of Pisa once stood.

These fly sculptures are scattered around the city and represent the patron saint of Girona.

The oldest Marian image in the Canary Islands still impresses people nearly half a millennium later.

This historic electric train has operated with regularity since the early 1900s.

A lovely look back at the manufacture and use of paper in all its forms.

More than 70 detailed dioramas—including some rather nontraditional ones—fill this charming museum.

The grotto where Saint Ignatius of Loyola lived as a hermit for nearly a year.

Medieval ruins nestled within a breathtaking swath of Spanish nature.

Peek into a cave of giant, glimmering crystals.

A delightful museum devoted to the history of books.

Hundreds of preserved dinosaur footprints can be found along a hiking trail in this small village.

This beautiful spit of land was once the summer playground of the king of Spain.

The cathedral of a controversial, conservative, schismatic sect that declared the Catholic Church heretical and founded its own succession of popes.

This enormous censer uses a pulley system installed over 400 years ago.

This charming, medieval walled village is Spain's first "book town."

The walls of these four caverns are filled with art that dates back to the earliest human presence in Europe.

A spectacular walk on the flank of a gorge.

This stunning iron gate designed by Modernist architect Antoni Gaudí is filled with mythic symbolism.

This 19th-century fountain's namesake animal isn't what you think it is.

A daily pyrotechnic celebration marks a beloved tradition during Valencia's festival season.