A completely underwater art museum sends a stark message about humans' impact on the environment.

Considered the birthplace of the Copper Age and Bronze Age, the river is tinted red from 5,000 years of mining.

Village situated on a narrow volcanic escarpment.

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

Mysterious Spanish catacombs of unknown origins.

Cliffside houses provide a spectacular view from their perch above the valley.

An architect transformed this abandoned cement factory into his castle-like workshop.

A landscape decorated with enormous skull sculptures.

A temple to modernity, tucked away amid Barcelona's more well known museums.

An isolated village literally built into the crevices and rock formations of a mountain.

A Spanish forest is filled with mysterious stone carvings.

At the foot of a waterfall lies a peaceful swimming lagoon and evidence of over 60,000 years of human habitation.

Bacteria and algae give the salty water its bubblegum hue.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

An enchanting monastery in the Spanish countryside appears lifted from a fantasy tale.

Wonderland replication in progress by one persistent man.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

Mountain where Jesus was first tempted by the Devil.

Gaze upon chocolate sculptures depicting everything from chariot races to Gaudí's famous church at this shrine to sweets.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

This cemetery features modernist statues as strange as its name.

This semi-secret storybook hedge maze is also the oldest garden in the city.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.