Nearly every wall in this French villa has been "tattooed" by artist Jean Cocteau and other famous painters.

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

The construction of a tram line unveiled hidden remnants of the old medieval city.

Artist's eccentric property excessively decorated with found objects and work of his own.

This massive blockhead sculpture hides an entire library.

An Orthodox church built by the Royal Family for the Russian community exiled to the French Riviera.

The largest medical and anatomical collection in France lies hidden from the public.

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

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

A unrivaled and rather horrifying collection of wax dermatological models.

Known as the "Dodo Manège," this carousel features a herd of animals that have disappeared—or may be gone soon.

Paris' fabled purveyor of exotic taxidermy and natural history curios.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

A haunting collection of the vanished and disappearing natural world.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

This museum in a Paris apartment gives a unique look at the iconic French singer's life.