A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

Memorializing the bravery of one young woman facing the monster of her age.

A chapel on a volcanic core, marking the end of a successful journey.

An unsettling shrine dedicated to the ravenous beast that prowled 18th-century France.

Hundreds of hidden passageways weave through the old quarters of Lyon.

A tiled, multi-level garden of survival in Lyon.

The fantastic architectural models of a French traveler.

Nicknamed the "Museum of Horrors," this French anatomical collection has been fascinating visitors for over a century.

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

Exquisite examples prehistoric bas-relief carvings.

One of the world's most complex timepieces.

Ivy-covered Medieval tunnels cut through this charming town in France's Loire Valley.

An enchanting work of outsider art, full of whimsical sculptures and carvings.

A self-built mosaic house and sculpture park.

The remains of 40,000 humans, meticulously stacked in a tiny churchyard shed.

Hundreds of secret cabinets built into the walls of legendary poisoner's private work room.

The remains of this ornate chapel now act as a portal to a cramped French cemetery.

A beautiful lighthouse with as many steps as days in the year, as many windows as weeks, and as many levels as months.

Personal garden filled with mosaics made of recycled garbage.

This enormous "cloth of the conquest" depicts the Norman invasion of England in mind-blowing detail.

Folklore and history carved into Brittany's coast.

The birthplace of the ferocious William the Conqueror, this castle is awash in medieval history.

This 1,400-year-old abbey was once a powerhouse for music and intellectualism known across Normandy.

Figures of unknown origin carved into the surfaces of underground caves.