The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

One part local history, 99 parts gruesome haunted house.

A magnificent tomb that was the final resting place of the Dukes of Hamilton.

An existential riddle in the world's largest ancient castle.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Macabre astrological automaton clock dating to the late 1400s.

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

The video game-themed street art first popped up in the French city.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

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

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

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

Now housed in a museum, this giant pink elephant stood in downtown Seattle for more than 60 years.

Statue of Lenin, from Cold War era Czechoslovakia, now in a neighborhood of Seattle.

Allowing humans and fish alike to migrate from freshwater to saltwater and back again.

The flock of plastic poultry is an ode to the classic comedy staple.

Residents of Fremont in Seattle have considered it the center of the universe since the 1970s.

A wall of chewing gum moonlights as collective art.

This former coal gasification plant found a curious second life as a popular public park.

A giant Troll lurks under one of Seattle's oldest bridges.

A museum dedicated to the history and exploration of both popular music and science fiction.

Taking the 3D art experience far beyond blue and red glasses.