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

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

This stunning natural double arch, the largest in the Alps, went undiscovered until 2005.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

Beautiful carved tunnels.

The fantastic architectural models of a French traveler.

For hundreds of years, automatons moving to metallic music have been marking the passage of time.

An aluminum skeleton brings Chinese mythology to the French shore.

Two awe-inspiring globes from the reign of the Sun King hang from the ceiling of France's national library.

This salt marsh in Southern France is as pink as the flamingos that inhabit it.

Historic medieval fortified city in southwest France.

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

An icy lake tucked among jaw-dropping alpine panoramas.

The famous winding walk at Chartres is surrounded in mystery and myth.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

Do these monsters look familiar? The gargoyles on this church are all from pop culture.

Natural history museum celebrating biodiversity with a parade of taxidermy animals.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

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

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

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 subterranean shelter remains intact under a busy Paris railway station.