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

These quaint French houses dangle precariously over a precipice.

This bridge was constructed from the rubble of the infamous Bastille.

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

The Argonaute submarine was the French navy's pride and joy in the 1950's.

Beautiful carved tunnels.

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

Two small chapels housed inside an ancient tree.

The fantastic architectural models of a French traveler.

A short distance from the Eiffel Tower is the final resting place of several of the city’s more well-known and interesting characters.

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

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

The oldest and smallest cemetery in Paris is only open to the public twice a year.

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

An enchanting work of outsider art, full of whimsical sculptures and carvings.

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

The largest underground church in Europe.

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

A Gothic cathedral created from volcanic rocks.

Architect Le Corbusier built his friend a cubist house to match his impressive collection of cubist art.

A medieval military street hidden beneath a charming French fishing village.

A well-preserved medieval village nested on a rocky outcrop and surrounded by a network of cliffs, natural bridges and canyons.

A mud statue stands in the dark tunnels, seeming to hold up the weight of the city above.

An aluminum skeleton brings Chinese mythology to the French shore.