This historic Amsterdam bar used to accept sailor's monkeys as payment.

The attic of a four-century-old canal house hides a clandestine church.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

The former home of a mad diplomat is said to still be marked in bloody, arcane scrawls.

A beautifully eclectic mix of architectural styles.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

Cat art as far as the eye can see.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

This basement museum explores the art and artistry of fascism.

This impressive collection of rare books on ancient mysticism inspired author Dan Brown.

The world's only museum devoted to the wonders of fluorescence.

A floating cat sanctuary on an Amsterdam canal.

An abandoned beach resort in Normandy reclaimed by artists.

Unable to build support structures on glaciers, the engineers for this tramway were forced to design a unique system.

An icy lake tucked among jaw-dropping alpine panoramas.

Trek up this glacier before it disappears.

A modern-day Lascaux cave underneath Paris.

The recovered bones of martyrs slaughtered during The Terror are on display in this church crypt.

The floorboard scrawling of a tragic madman is on public display outside a Paris hospital, much to the dismay of its opponents.

Noirish green neon marks the location of one of the oldest private detective agencies in France.

The former home of France's controversial pop maestro is almost completely covered in ever-changing tributes and graffiti.

This surreal statue brings a famous French novel about a supernatural cad to arresting life.

Pitié-Salpêtrière was the dumping grounds for women who received the dreaded diagnosis of "hysterical."