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

Wonderland replication in progress by one persistent man.

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

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

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

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.

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

A lush indoor jungle fills this bustling Madrid transportation hub.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

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

A beautiful but toxic fountain of mercury.

A Faraday Cage protects cars from a nearby high-power transmitter.

A crumbling bakery where forced laborers from the nearby concentration camp toiled to feed their fellow prisoners and Nazi soldiers.

Hitler's bleak vision of relaxation still stands as a mostly abandoned 10,000-room resort complex.

The ruins of an abandoned crematorium haunt an eerie deserted German cemetery.

An old department store turned Nazi prison turned artist commune.

The abandoned remains of this Victorian brewery hide crumbling bowling alleys and rusting industrial gear.

Come stay at a live-in art installation.

The ruined remains of the airport Claus von Stauffenberg departed in his failed attempt to kill Adolf Hitler.

One of the most easily accessible examples of the rare 1960s UFO houses.