A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

The recovered bones of martyrs slaughtered during The Terror are on display in this church crypt.

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

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

Ancient paintings known as the "Sistine Chapel of Cave Art."

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

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

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

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

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

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

A museum of magic with a Sadist past.

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

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

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

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

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

What was once England's second-richest abbey is now a haunting ruin.

A nuclear bunker built to shelter the politicians and important people of Scotland in case of nuclear attack.

This shell of a historic manor house on the Isle of Wight is said to be the most haunted site on the island.

This eclectic sanctuary is a hodgepodge of various architectural styles, all crammed into one building.

The ancestral home of beloved English poet Lord Byron has a bizarre history.