The signs of a long buried road can still be found hidden beneath a London sewer grate.

Hear the quietest sound from across the dome.

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

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

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

The curios of pharmacist and collector Henry Wellcome.

Rebuilt remains of a temple to Roman god Mithras.

A student driver's nightmare.

Eighty million natural history specimens call this gargantuan museum home.

Hidden beneath the streets of London is a secret subway that only carried mail.

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

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

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

A kaleidoscopic warehouse-maze of handmade neon signs.

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

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

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

The celebrated eyesore created by starry-eyed sweethearts.

This lesser-known Frank Gehry building houses a treasure trove of cinema history.

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

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

Notorious artist squat renovated into legal studios.

France's most famous cemetery, with some of its most curious tombs.

The vast, legendary catacombs hold secrets much stranger than stacked bones.