Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

This Parisian café sticks almost exclusively to an ethos of reuse.

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

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

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.

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

Abandoned railway line circling the city of Paris.

France's most famous cemetery, with some of its most curious tombs.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Once home to one of the oldest banks in the world, this building is also where Marco Polo's famous travelogue was written.

A stunning cemetery famous for its extraordinarily delicate & lifelike mourning sculptures.

A roadway designed for a visiting monarch.

The intricate geometry inside this Baroque-style dome was designed to create "terror of the human soul."

The Lowcountry color with the power to stop evil from entering a home.

In the world's oldest university is a stunning 17th century anatomical theater carved from spruce.

The remains of an ancient Roman city are hidden underneath Bologna's beautiful public library.

These steps offer a breathtaking view of one of Europe's most besieged fortresses.

Scotland's oldest purpose-built concert hall houses an incredible collection of ornate, centuries-old keyboards.