A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

The oldest stone house in Paris was built by its most famous alchemist.

The sign at the garden gate reads: "These Plants Can Kill."

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

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

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

This giant radio telescope would be a rusting ruin if it hadn't become such a beloved relic.

Nestled in the woods lies this land art project: a hybrid between park, maze and natural monument.

The nerve center of a massive, state-of-the art radio telescope that sprawls across Western Europe.

A radio telescope for listening to the stars, based in one of the cloudiest countries in the world.

Most complete collection of Gymnosperms in the world.

This stately council chamber hasn't changed since 1545.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

Abandoned railway line circling the city of Paris.

The world's only museum devoted to the wonders of fluorescence.

This Netherlands museum holds a gloriously mechanical collection of ornate musical automata.

The giant scales in this museum can still tell if someone is one of the devil's brides just by weight.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

A collection of objects supposedly singed by the hands of souls in purgatory.