This 18th-century sundial was designed to calculate the date of Easter each year.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

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

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

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

One of the most photographed buildings in a city known for its Modernista architecture is an abandoned squat.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

The oldest giants in Catalonia are now displayed in a 14th-century Gothic church.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Napoleon's childhood home is now open for people to explore the beginnings of France's short general.

A quirky bookstore hidden beneath a sea of whitewashed Greek villas.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

Legend says this sacred tree was a gift from goddess Athena.

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

A section of the long chain that blocked enemy ships from entering Constantinople.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

1513 Turkish world map, full of European state secrets and snarky commentary.

A marvel of Byzantine engineering under the streets of Istanbul.

The walls of America's oldest masonry fort famously "swallowed" cannonballs.

Arrr! The most authentic collection of pirate artifacts in the world... matey.

It's a pretty creepy lock-up.