Science fiction's grandfather has a fittingly marvelous tomb.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

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

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

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

One of the greatest maze designer’s greatest mazes.

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

The largest medical and anatomical collection in France lies hidden from the public.

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.

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

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

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

Egyptian Revival movie palace abandoned for decades and restored in 2013.

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

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

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

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

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

A surrealist timepiece by the artist of melting clocks.

A mechanized clock where a man fights off a dragon, crab, and rooster.

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.

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