This underground transport hub doubles as an art gallery.

This exquisite, alienesque piece of Soviet architecture is being threatened by modern shopping malls.

One of Europe's largest supercomputers is housed inside of a disused chapel.

Giant eggs, walls of bread, and nightmare surreality mark the largest collection of works by Salvador Dalí.

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

A trio of hidden hot tubs takes advantage of Iceland's natural geothermal vents.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

Wonderland replication in progress by one persistent man.

Week-long block party becomes a competition for the best decorated street.

Bacteria and algae give the salty water its bubblegum hue.

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

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

Monumental sculptures guard many of the graves, transforming this necropolis into an open-air fine art museum.

A Kyiv-based repository for all manners of discarded curiosities.

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

This natural Icelandic fissure allows divers to swim right between two volatile tectonic plates.

The oldest (maybe) swimming pool in Iceland is a stunning oasis built into the side of a lush hill.

In paradise, feral pigs have claimed an island all to themselves.

Beijing's version of Disneyland, completely abandoned, mostly destroyed.

Beijing's expansive subterranean hiding spot now crumbles away as a tourist destination.

The embalmed remains of the communist leader lie within a custom crystal coffin.

North Korea's massive art and propaganda factory now has an official gallery space in Beijing.

This probably wasn't what Mao had in mind.

The most famous location in China was home to whole dynasties worth of imperial rulers.