This French castle is said to have once held the Holy Grail but is now a gorgeous mountaintop ruin.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

This is what trains will look like after the zombie apocalypse.

A mosaic-tiled house built by graveyard sweeper Raymond Isidore.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

The great Italian Renaissance painter was laid to rest here in the Chapel of Saint-Hubert.

This stunning French estate was so lavish that it landed its original owner in jail for the rest of his life.

A public park off the beaten path with a beautiful waterfall and 13th century Cistercian abbey.

Sleep in a climate-controlled plastic bubble for the night.

An ancient monastery, a locked room, and a mysterious book heist.

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

Original cabaret handbills, posters, and feline artwork are a purrfect highlight of the Museum of Montmartre.

Ghosts of France's colonial past.

The fantastic architectural models of a French traveler.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

Massive puppet-automaton machines created by French artist collective Machines de l’Ile.

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

Two small chapels housed inside an ancient tree.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

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."

One of the greatest maze designer’s greatest mazes.

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.