As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

The final resting place of the poets Shelley and Keats.

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

The oldest operating pharmacy in the world features 800-year-old recipes.

Thousands of well-dressed mummies below a monastery.

Stalactites and stalagmites in a beautifully lit cave.

Renaissance villa and gardens complete with a tormented colossus.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

A submerged archeological park still holds the wonders of a Roman Sodom.

A 16th-century horror show built in a lovely Italian garden.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

The haunting cadaver tomb of a famous French poet, playwright, and filmmaker.

The home where the famous astrologer wrote some of his most telling prophecies.

The first modern cemetery of Lyon is complete with more than 200 chapels and monuments.

The mummified heart of Louis XVII, the lost dauphin of the French Revolution.

Perfume museum and library.

This recessed garden protects thousands of mountain plants by creating its own microclimates.

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

Nicknamed the "Museum of Horrors," this French anatomical collection has been fascinating visitors for over a century.

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

The deserted pirate-themed restaurant still entices explorers.

This collection of French root art looks like an indoor fairy wonderland.