Scattered throughout London are ancient remnants of the city's former bounding wall.

A cluttered and astounding collection of antiquities and curiosities.

An incarceration museum on the spot of possibly the oldest prison in England.

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

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

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

Hear the quietest sound from across the dome.

Eighty million natural history specimens call this gargantuan museum home.

The curios of pharmacist and collector Henry Wellcome.

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

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

A student driver's nightmare.

Famously misunderstood wonder of the ancient world

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.

These "anatomical machines" are only one of the many strange items in this Italian crypt.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

The curious underground history of keeping Paris clean.

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

The very center of Paris is surrounded by a bevy of strange good luck rituals.

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