This frog-themed restaurant was frequented by Picasso, Saint-Exupéry, and more.

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

Indents in the pavement are all that remain from a grisly death machine in Paris.

Hidden in the garden of physicist Erwin Schrödinger's house is a life-size figure of a cat from his famous thought experiment.

This charming fountain honors Felix Salten, the creator of the iconic storybook deer.

A 200-year-old tavern challenges guests to finish a glass of wine while hanging from a ceiling beam.

One hundred years ago this small house in downtown Zürich became the birthplace of the Dada movement.

Once a 19th-century brasserie, this McDonald's exterior celebrates Alsatian design and the "King of Beer."

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

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

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

Paris' linguistic guide to the international language of, yes, love.

A museum of carnival attractions where you are invited to ride the rides.

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

This massive library holds what was once the largest book collection in the world.

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

Venice's island of the dead.

Stare out over the lagoon and beyond from this 10th-century campanile on the island where the city of Venice began.

The small peaceful island off the Venice tourist circuit is where the city began more than 1,500 years ago.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

Hanging within this medieval church are the bones of a beast allegedly slain by a fourth-century saint.

A 22-million-year-old sandstone cave is a natural habitat for award-winning cheese.

Lucerne's central prison was converted into a tourist hotel with a bare minimum of changes.