A beautiful but toxic fountain of mercury.

This art installation at an abandoned lipstick factory has distinct anti-capitalist vibes.

A spectacular walk on the flank of a gorge.

You can soak in three relaxing pools filled daily by the tide.

Hundreds of caves once used to store grains and animal feed.

Translating as "The Jump of the Girlfriend," this stunning waterfall has a tragic legend behind it.

Spain's stunning solar energy plant.

Volcanic rocks ground down into sand make this Spanish beach as black as night.

A science fiction-inspired apartment building designed by a famous Spanish architect.

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

This house's itty bitty size means no humans allowed.

A landscape decorated with enormous skull sculptures.

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

A lush indoor jungle fills this bustling Madrid transportation hub.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

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

Wonderland replication in progress by one persistent man.

Bacteria and algae give the salty water its bubblegum hue.

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

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

An uninhabited village that preserves and documents rural architecture and an endangered way of life.