The curious underground history of keeping Paris clean.

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

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

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

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

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

Down a cobblestone alleyway is a museum dedicated to Romanticism, with a secret garden.

"In the Dark" Restaurant in Paris offers dinner in complete darkness.

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

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

This museum houses an imposing skeleton army comprised of creatures great and small.

France's national museum of scientific and industrial instruments.

A museum of magic with a Sadist past.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

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

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

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

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

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

Abandoned railway line circling the city of Paris.

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