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

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

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

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

This Roman arena once played host to bloody gladiatorial battles.

The blowhole bursts spectacularly right next to the buildings in a medieval seaside town.

Originally planted by the ancient Carthaginians, this sprawling palm grove is one of the largest in the world.

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

A reservation-only highland forest reserve of endangered Pinsapar firs stands above a village in Andalucía.

The ruins of a 2,000-year-old Roman fishing village perched on one of the best beaches in Spain.

A complimentary beverage is offered to the bodega's resident rodents every day.

An Antoni Gaudí masterpiece in Astorga.

The oldest Roman lighthouse still in use.

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

For more than half a millennia, this automaton has rung an hourly bell.

The former home of a conniving 17th century politician is now a high-end hotel.

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

Abandoned 18th century weapons factory in the Aezkoa Valley.

The site of a legendary battle immortalized in medieval literature.

This Navarrese cave's history of witchcraft and pagan ritual is not just embraced, but recreated each year.

Abandoned blockhouses from Nazi Germany's Atlantic Wall erode into the sea on a French beach.

Northern Ireland's Brobdingnagian stepping stones.