One of the best examples of the modernist movement in Madrid.

One of the most important Celtic-Roman archaeological sites in Spain.

These old towers extract salt from the sea.

This 15th-century aqueduct with distinctive pointed arches was used for irrigation in the Vinalopó valley.

The prolific artwork of a self-taught sculptor.

A rocky face gazes out over an enormous volcanic crater.

Fragments of human bones are embedded in the walls of this quaint alley.

Drink the 'Blood of Christ' in this Roman Catholic fever dream.

An otherworldly art experience.

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

This ancient amphitheater was restored in the early 1990s.

This small Spanish village is home to dozens of public paintings meant to trick the eye.

Disturbing winged beings decorate the walls of this strange abandoned hermitage.

A small house in Tazones, completely covered in shells.

An elaborately decorated house sits on an otherwise quiet street.

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

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

A series of well-preserved ruins show the culture of the ancient Benehoaritas people.

Nicknamed the "Spirit of Paul Klee," this colorful apartment building features an array of multicolored panels.

This house covered in small stones was the work of one man over the course of nearly 30 years.

This magnificent brick dome was made with an unusual design method.

This Gothic church houses ornate royal tombs and a magnificent gilded altarpiece.

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

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