The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

This frog-themed restaurant was frequented by Picasso, Saint-Exupéry, and more.

Statue of death tucked in the University of Medicine courtyard.

Fur-lined metal pod dangling in the French countryside.

A Christian retreat founded to welcome refugees fleeing from the Nazis during World War II.

One of the most powerful religious centers in the Middle Ages, dubbed the founder of Western monasticism.

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

This church looks more like a spaceship than a house of worship.

During the 17th-century, orphaned infants were placed in this barrel to be cared for by the hospital.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

One of the greatest maze designer’s greatest mazes.

An architectural oddity of six stories, accessed by graceful ramps.

A gothic church dedicated to the love of wine.

The fantastic architectural models of a French traveler.

An art world insider finds himself battling for his artistic home.

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

This abandoned church in central Lyon is missing its front stairs.

This hidden garden boasts amazing views of Lyon.

Inside this museum, Christians were imprisoned when the Romans controlled Gaul.

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

Claude Monet was baptized in this lavishly ornate Paris church.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

The second-largest natural arch in the Chartreuse Mountains.

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