In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

A floating cat sanctuary on an Amsterdam canal.

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

Cat art as far as the eye can see.

Eighty million natural history specimens call this gargantuan museum home.

A collection dedicated to the treatment of disease, held in London's oldest hospital.

Repository for more than 22 million pickled specimens.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

A Victorian natural history and ethnographic museum with wonderful turn-of-the-century, science-book-esque evolution displays.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

The curios of pharmacist and collector Henry Wellcome.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

This South London cemetery holds the remains of more than 15,000 people.

A hands-off space for graffiti artists to hone and display their skills.

The anatomical-pathological collection of a man who changed surgery.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

Art and a pun, all in one.

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

Europe's second largest ossuary wasn't discovered until 2001.