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

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

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

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

France's most famous cemetery, with some of its most curious tombs.

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

A museum of carnival attractions where you are invited to ride the rides.

This California estate was either haunted by ghosts or the Marx brothers.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

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

Rome's ancient Etruscan rival, now a park full of ruins.

Abandoned cemetery of the former Psychiatric Hospital of Volterra.

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

This picturesque Umbrian city has a subterranean side that has long remained hidden.

This 16th-century monastery has been turned into a surrealist architecture compound.

Walk through a fairytale in Tuscany.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

A complex, nine-layer maze on the grounds of a Venetian doge's playground.

The plague quarantine island home to the alleged "Vampire of Venice."

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

Gods clash with machines in a power plant regenerated as a museum.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.