The curious underground history of keeping Paris clean.

One of the greatest maze designer’s greatest mazes.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

This Parisian fountain is a little bit fantasy and a little bit nightclub.

A subterranean shelter remains intact under a busy Paris railway station.

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

A grotto-like lodge decorated with gilded mosaics, rocks and a noisy waterfall was the setting for the most sumptuous pleasure house of 1900s Europe.

The history of radiation is on safe display at the foot of a radiation science laboratory.

A majestic lion statue guards this Parisian botanical garden, and feeds on an unsettling item.

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.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

Stroll through retro Paris while shopping for old postcards and discarded doll heads.

A museum of magic with a Sadist past.

France's national museum of scientific and industrial instruments.

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

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

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

A haunting collection of the vanished and disappearing natural world.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Local lore says two enemy dragons live within these breathtaking mountain lakes.

A hidden workshop for creating and restoring Papal mosaic masterpieces.

If you want to talk to the Pope you will have to stare down this surreal vision of Jesus rising from a nuclear hell.

An American ghost town hides along a side street in Scotland's capital.