The eclectic observatory castle of a 19th-century astronomer and explorer.

This crack in France's seaside cliffs once hid a sinister secret.

Exquisite examples prehistoric bas-relief carvings.

Guests can stay at a hotel in the former French abbey where lie the tombs of King Henry II and King Richard the Lionheart.

One of the great treasures of Neolithic art lies within this carefully constructed pile of rocks.

An atmospheric, medieval-themed book store hides in a 13th-century underground space.

This French "sea of rocks" is packed with stunning rock formations and its own medieval castle.

Folklore and history carved into Brittany's coast.

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

This triumphal arch celebrating the Sun King's conquest of Lille is a masterpiece of military architecture.

This army of concretions is an unexplained geological phenomenon unlike anything else in the world.

Resting on a hill overlooking the coast, these medieval ruins look completely deserted save for their restored chapel.

The ruins of a medieval castle linked to the murderous French lord that inspired the famous legend of Bluebeard.

A small house sits between two huge rocks, with its back to the sea.

A sublime medieval path adorns the marble floor of one of the most beautiful Gothic cathedrals in France.

For over 300 years this little carving has been the city’s good luck charm.

An underground city of ancient quarry tunnels hid thousands of Allied soldiers in WWI.

Natural mummies hidden in the crypt of a medieval French church.

There is a strange little carving of a person seemingly crushed by a pillar behind the remains of St. Thomas Aquinas.

A colorful piece of contemporary art cheerfully clashes with Lyon's historical architecture.

A remote hilltop covered in giant monoliths haunts the Brittany countryside.

The world's most famous cheese caves.

Series of underground houses inhabited continuously for centuries.

A beautiful Victorian statue shows France's enduring love of the rhinoceros.