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

Giant topiary dog once played a role in a terrorist bomb plot.

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

Geological storytelling.

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

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

Mountain where Jesus was first tempted by the Devil.

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

Three bridges and one giant canyon make up this fantastic Spanish settlement.

The "dragon babies" of southeastern Europe.

A miniature train-ride through Slovenia's largest cave system.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.

Moscow's imposing monument to the Space Age.

The oldest museum in Russia is home to a fascinating collection of nearly two million anthropological artifacts and anatomical curiosities.

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

This Transylvanian church has changed its denomination four times.

A medieval church built up to defend its village.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

A countryside Romanian cemetery filled with colorful crosses bearing lyrical, ironic, or satirical rhymes.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.