The ruins of an ancient Celtiberian town with incredible rock-cut buildings and a Roman aqueduct.

See replicas of Europe's most famous cave paintings and even some of the animals that feature in the art.

These striking ruins of a castle resemble a ship's stern.

An outsider folly near Madrid.

Whimsical sculptures and caves chiseled by nature over the millennia.

Abandoned 18th century weapons factory in the Aezkoa Valley.

One of Europe's largest groups of dolmens remains largely off the typical tourist track.

Guitarist Paco de Lucía overlooks travelers as they pass through this train station dedicated to his legacy.

The remains of an encyclopedic sculpture garden later used as an internment camp.

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

This art installation at an abandoned lipstick factory has distinct anti-capitalist vibes.

A must for film lovers in Madrid and home to the Spanish Film Library's projection space.

The unfinished final resting place of some of Spain's most prominent politicians.

Locals use these rock pools and waterfalls for swimming and cliff diving.

An ornate tower shows off a local artist's architectural flair.

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

Abandoned tunnels dug for the once-thriving sea salt industry on the coast of southern Spain.

The cathedral of a controversial, conservative, schismatic sect that declared the Catholic Church heretical and founded its own succession of popes.

Fascinating exhibits of prehistoric and ancient artifacts displayed with a uniquely modern touch.

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

The ruins of a bombed medieval village memorialize the destruction of the Spanish Civil War.

Haunted tuberculosis hospital built by the patients.

A neighborhood park in the city of Cáceres hides what some believe are revolutionary examples of Neanderthal cave art.

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