Not far from Madrid, a set of perfectly preserved trenches date back to the Spanish Civil War.

Rumors and legends of secret Nazi activities surround this eerily remote island mansion.

An unexpected ghost village lurks on the southeast coast of Tenerife.

This abandoned naval battery stood at the ready as recently as the 1980s.

Abandoned 18th century weapons factory in the Aezkoa Valley.

An abandoned socialist utopia built in the late 19th century.

This Arab fortress was once the largest citadel in Western Europe.

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

Haunted tuberculosis hospital built by the patients.

The largest medieval water tank on the Iberian Peninsula is preserved beneath the Cáceres Museum.

The atmospheric ruins of a historic church can be found on a hill above the city of Oviedo.

This huge abandoned fortress hidden inside a mountain holds a world of subterranean secrets.

A magnificent, long-abandoned castle built in the wake of the reconquest of Spain.

The unexpectedly beloved remnants of a controversial thermal power plant.

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

The hidden ruins of an old hydroelectric plant reclaimed by nature.

One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

This ancient Spanish castle sits high upon a hilltop.

A site where “the ravages of the war are more striking…than any other place in contemporary Spain.”

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

Its appearance in "Game of Thrones" may spur on the long-awaited restoration of this medieval shipyard.

This former charity hospital for elderly clergy houses some of Seville’s most treasured paintings.

Stunning Roman aqueduct used for 1900 years and still standing.

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