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

A hidden medieval crypt where a famous legend says the devil used to teach black magic.

These "mermaids" that surround a plaza in Segovia are rather sphinx-like.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

A breathtaking and biodiverse wilderness in the mountain setting of Ernest Hemingway's "For Whom the Bell Tolls."

A subterranean relic of the Spanish Civil War hides below this picturesque park.

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

This postmodern apartment block was designed to be a vertical neighborhood.

A towering monument in Spain has proven to be more labor-intensive than initially planned.

A reproduction of the famous prehistoric cave paintings is hidden underground at the National Archaeological Museum.

This enigmatic artifact is a rare depiction of an ancient Iberian noblewoman.

An iconic and controversial ancient Iberian funerary urn with a hauntingly penetrating gaze.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

For decades, Puerta del Sol has been illuminated by a giant, guitar-wielding bottle of sherry.

This small museum tucked within a subway station holds pieces from Madrid's past.

Part of the medieval watchtower is displayed in an otherwise ordinary parking garage.

An ancient Egyptian temple in the middle of Madrid, Spain.

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

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

The fragmented remains of a massive public bath connected to the city's water supply.

Whether they are bulls or pigs, these ancient animal sculptures are fascinating relics.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

According to tradition, King Phillip II supervised construction of the seat of his empire from this seat carved into rock.