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

The celebrated eyesore created by starry-eyed sweethearts.

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

The hallucinogenic center of the ancient world.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Where commuters walk through remnants of an ancient Greek necropolis.

Eighty million natural history specimens call this gargantuan museum home.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

Spitalfields' regal market goat is said to be a monument to the area's migrant population but most are pretty sure it's just a goat.

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

This one has sailed five times as far as Sir Francis Drake's famous ship.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

A quiet memorial to those who died saving others in the heart of the City of London.

The curios of pharmacist and collector Henry Wellcome.

Dictionary Johnson’s favorite feline.

Children's hospital in London that operates on royalties received from Peter Pan, which J.M. Barrie signed over in 1929.

The remains of the great moral philosopher reside in a university in London.

A cluttered and astounding collection of antiquities and curiosities.

One part local history, 99 parts gruesome haunted house.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

A church of bones, decorated with 40,000 human skeletons.

The world's tallest boat lift stands as a massive piece of industrial tourism.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

This ghost town in Belgium will lose its street art when it ceases to exist.