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

A curious memento mori hangs in the magnificent Cathedral of Segovia.

This stop on the Camino de Santiago stands high above the underwater ruins of a medieval town.

The oldest Roman lighthouse still in use.

An accidental trick of light casts the perfect shadow of a pilgrim of the Camino de Santiago against the cathedral wall.

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

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

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.

Catalonia Tradition: Beating the hollow Christmas log until it defecates in your fireplace.

The first monument in Estonia that was made by an Estonian sculptor.

Walk along the medieval fortifications that have been protecting Tallinn since the 14th century.

An 18th century wonder of the world, lost in WWII, re-created at the Catherine Palace.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

Dublin's most modern, visually spectacular bridge is modeled after Ireland's national emblem.

A floating cat sanctuary on an Amsterdam canal.

Climb inside an iron crystal magnified 165 billion times its normal size.

A little sculpture with a large wardrobe.

The chefs at El Diablo use heat generated by an active volcano to cook the food.

Visit a surreal landscape so otherworldly NASA actually used it to train the Apollo 17 crew.

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

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