This Moorish fortress has guarded Málaga from the slopes of Gibralfaro hill for nearly a thousand years.

A visionary precursor to the Internet made of index cards.

Since its accidental discovery in 1977, this sarcophagus has been described as "the greatest masterpiece of Merovingian sculpture north of the Alps."

A 1st-century Roman aqueduct running straight through a children's playground

This castle has links to Portugal’s founding and struggles for independence.

Gustave Eiffel's masterpiece until the Eiffel Tower was built.

A hidden three-foot-wide house separates these two regal churches.

A stunning 18th-century site where pilgrims ascend by a series of punishing stairs only to return via funicular.

This enchanting natural park is a magical example of a temperate rainforest in Europe.

The oldest Roman lighthouse still in use.

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

Small-town scandal, transformed into timeless pop art

An abandoned 6th-century monastery features a medieval map of the known world.

Remarkably intact Roman stone fortifications have encircled this Spanish city for centuries.

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

One of few vertical lava tubes in the world accessible by foot.

The extensive relics of an ancient Roman and Phoenician fish processing plant hide in a town park.

Despite its grandiose name, this enigmatic first-century void under the town is no cave, and it's possibly not a palace either.

Look closely and you'll spot the remains of an ancient Roman aqueduct beside this fountain.

This abandoned, turn-of-the-century astronomy hub is now the subject of more photographs than it ever took.

These megalithic tombs contain some of the largest stones ever moved in prehistory.

A New York–based physician returned home to Spain to build his own elaborate monument to Christopher Columbus.

This medieval synagogue survived the Inquisition as a hospital and church.

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