Meant to resemble a massive tree, the building is the best example of Spanish organicist architecture in Madrid.

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

The 20th-century church looks like a rustic version of the Sagrada Familia.

The largest salt farm in the Canary Islands is located at the foot of an active volcano.

This Art Nouveau gate still stands at the former entrance of a 20th-century Spanish writer's colony.

A pre-Hispanic pyramid in the middle of a tourist district in the Canary Islands.

These abandoned country fairgrounds are filled with replicas of Spanish monuments.

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

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

This small Spanish village still pays homage to the Spaghetti Western films that were shot there in the 1960s.

A long strip of fossil-filled limestone makes up this natural bridge above a rushing stream.

Possibly the oldest masonry dam in all of Europe.

An abandoned airport in the middle of nowhere.

With a facade that measures just 107 centimeters, this five-story building is one of the skinniest in Europe.

Once the grandest synagogue in medieval Spain, it now stands as a memorial of the 15th-century Jewish exile.

Sanctuary on a ridge near an ancient shrine to a "Black Madonna" built by the founder of Opus Dei.

Indigenous cultures believed all life would end if this enormous rock toppled.

Sometimes called the Banksy of Madrid, Muelle was a pioneer of street art in the Spanish city.

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

To fit bodies into this Renaissance crypt, they were first left to decompose in the crypt's rotting room.

This historic electric train has operated with regularity since the early 1900s.

This multi-level, aqueduct-footbridge hybrid is one of the greatest works of the Spanish Renaissance.

A road that winds through this natural cave is the only way to access the small, appropriately-named village of Cuevas.

If you like Art Deco you will love this bridge.