An eerie collection of the surviving structures from a past celebration of the future.

The world's most elegant power lines.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

Single runway interrupted by a busy road that cuts across its middle.

A site where “the ravages of the war are more striking…than any other place in contemporary Spain.”

This abandoned mansion has a window for every day of the year, and is a temple for ghost hunters.

An abandoned mine now resembles a post-apocalyptic landscape of derelict buildings and blood-red pools of water.

Originally planted by the ancient Carthaginians, this sprawling palm grove is one of the largest in the world.

Bacteria and algae give the salty water its bubblegum hue.

Vibrant street art created with mixed media.

Abandoned Nazi train station turned underground astroparticle laboratory.

The top of society once luxuriated in this world-class hotel, which continues to impress, even in ruin.

A French valley with forests so lush it was nicknamed "the Small Amazonia of the Pyrenees."

This Navarrese cave's history of witchcraft and pagan ritual is not just embraced, but recreated each year.

A museum dedicated to the Spanish occult in a town that was terrorized by the Inquisition.

Eccentric sculpture garden brings Basque mythology to life.

One of the largest ossuaries in Spain is packed from floor to ceiling with bones.

Abandoned medieval hill town.

The world's largest solar furnace uses 10,000 mirrors to concentrate the sun's rays to generate power.

A whale rib was used to advertise the store by the arch that offered exotic goods from far away.

The skulls and bones of thousands of soldiers line the walls of this small Italian chapel.

The bones of some 7,000 soldiers killed in the historic Battle of Solferino are stored here.

An Orthodox church built by the Royal Family for the Russian community exiled to the French Riviera.

An ancient rogue artist community hidden next to one of the world's most glitzy and glamorous cities.