This Arctic mining town is home to a cat that's spent years masquerading as a fox.

This abandoned mining village was predicted to resist decay longer than any other modern human settlement.

Cold storage for agricultural biodiversity.

A maze of crosses marks the jumbled divide between the Netherlands and Belgium.

Napoleon's childhood home is now open for people to explore the beginnings of France's short general.

This futuristic observatory at the top of the Pyrénées offers unrivaled views.

The world's largest reflecting pool is just two centimeters deep.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

An icy lake tucked among jaw-dropping alpine panoramas.

This frog-themed restaurant was frequented by Picasso, Saint-Exupéry, and more.

Walk through spectacular aisles of hanging meat and wagon wheel–sized cheese at the world's largest wholesale food market.

Original cabaret handbills, posters, and feline artwork are a purrfect highlight of the Museum of Montmartre.

Statue of death tucked in the University of Medicine courtyard.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

A subterranean shelter remains intact under a busy Paris railway station.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

"In the Dark" Restaurant in Paris offers dinner in complete darkness.

France's national museum of scientific and industrial instruments.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

An early 20th-century bullring converted into a modern shopping center.

This quaint Spanish village agreed to be painted blue as a marketing stunt but found that they preferred it that way.

Abandoned Nazi train station turned underground astroparticle laboratory.