Read between the lines of the subway map to find the hidden abandoned Civil War fort.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

This abandoned mansion has a window for every day of the year, and is a temple for ghost hunters.

A Spanish town built into the cliffs.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

This quaint Spanish village agreed to be painted blue as a marketing stunt but found that they preferred it that way.

Single runway interrupted by a busy road that cuts across its middle.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

The medieval town's star-shaped walls are geometrically dazzling, though not entirely impenetrable.

One of the largest ossuaries in Spain is packed from floor to ceiling with bones.

The Cathedral of Salamanca has a number of unusual carvings but none so surprising as a modern astronaut.

An eerie collection of the surviving structures from a past celebration of the future.

Spain's stunning solar energy plant.

A 16th-century Andalusian palace.

The world's largest wooden structure.

The final resting place of the great navigator, or maybe his brother.

Walls of stone rise up from sinkholes caused by underwater erosion.

Numerous sculptures set along hiking trails symbolize and idealize the relationship between man and nature.

A display of torture devices used in the Spanish Inquisition and other scourges of medieval Europe.

The ruins of an ancient stadium that hosted gripping chariot and horse races.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

Originally used to sell brandy, the bull-shaped billboard became an iconic symbol of Spain.

The mysterious large white cross visible from the runway is a memorial to a massacre during Spanish Civil War.