One of the famous Czech artist's lesser-known Prague installations appears to be a glowing fetus affixed to a drainpipe.

Walk through Czech history in Prague's largest graveyard.

Countless grotesque faces stare out from this eerie Prague art wall.

Two stunning 17th-century libraries and a cabinet of curiosities.

The oldest operating apothecary in the US has treated everyone from Thomas Edison to Mark Twain.

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

A New York garbage depot holds a secret collection of weird and wonderful refuse.

Try not to get slimed in Tribeca.

New York's oldest magic store.

A terrific purveyor of natural history objects and curios.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

A modern-day Lascaux cave underneath Paris.

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

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.

A counter-culture bookstore like no other hides in plain sight in the streets of Paris.

A museum of carnival attractions where you are invited to ride the rides.

This massive library holds what was once the largest book collection in the world.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

Notorious artist squat renovated into legal studios.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This top-secret nuclear bunker hidden in a Bosnian mountain has been converted to a modern art exhibition space.

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.

The place where World War I began.