This modern arts center is built around a gem of late-Baroque architecture.

This museum is housed in an unassuming building that witnessed one of the most daring feats of satire in modern history.

This French chateau is home to the world’s largest private collection of fighter jets.

One of the largest Roman settlements in Portugal.

This star-shaped military outpost is now simply trying to protect itself from neglect.

This abandoned gold mine found a second life as a post-apocalyptic film set.

One of the most well-preserved castles in Italy also contains a rare medieval example of a port fortification.

The deepest hole drilled in the name of science, where evidence of Precambrian life was found.

Built to power trains, the engines in this building provided the entire city of Madrid with electricity during the Spanish Civil War.

This 18th-century project to build the world's tallest gravity dam was never completed.

Long tunnels run under the ancient chariot racing circuit to the tower.

This ancient tunnel is one of the most important examples of Roman hydraulic engineering in Spain.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

Seaside ruins of a settlement that date back to the first century B.C.

This amended headstone marks the grave of a participant in one of the most successful military deceptions of all time.

The unexpectedly beloved remnants of a controversial thermal power plant.

Hundreds of caves once used to store grains and animal feed.

The largest prehistoric cemetery on the Balearic Islands dates back over 2,500 years.

Two towns are linked by an engineering marvel masquerading as a boring suspension bridge.

This ancient Spanish castle sits high upon a hilltop.

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

Volcanic rocks ground down into sand make this Spanish beach as black as night.

A Romanesque tower appears when water levels drop.