A towering baroque basilica jutting out of the French countryside.

Abandoned blockhouses from Nazi Germany's Atlantic Wall erode into the sea on a French beach.

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

The man who introduced reinforced concrete to the world demonstrated its genius by using it to build his own house.

A small museum of antique transport that's a must-see for bicycle lovers.

A castle-like sea fort from the 17th century is now a museum to oyster farming.

A crumbling island fortress that seems to be covered in a field of stone crosses but is simply incomplete.

The industrial architecture honors the laborers who brought the Exposition Universelle of 1900 to life.

The haunting concrete remains of a Nazi pebble crusher can still be found in this small French commune.

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

Longest canal tunnel in the world, abandoned in the 1960s.

A huge Megalithic chamber tomb located behind a cafe.

Trek into the depths of the cave where 17,000-year-old paintings exist alongside 400-year-old graffiti.

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

Site of one of World War I's most horrific scenes.

French Time Capsule-19th Century home revealed to the public.

Fighting the British and making game shows for over 150 years.

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

A massive, secret marina for the Nazis' most formidable weapon in the Atlantic.

His "Lionheart" is entombed separately from the rest of his body.

From carts to cars, this leftover Roman bridge in France has managed to survive for centuries.

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

A memorial to the nearly 10,000 American soldiers laid to rest on the beaches of Normandy during WWII.

These medieval ruins have survived since the 12th century, even providing shelter from the Nazis.