Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

A surrealist timepiece by the artist of melting clocks.

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

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

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

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

A counter-culture bookstore like no other hides in plain sight in the streets of Paris.

A haunting collection of the vanished and disappearing natural world.

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.

One woman's decades-long obsession with the "La Fée Verte."

A rooftop restaurant hides in plain sight atop Vienna's Palace of Justice.

Dine amidst exotic plants at this former royal greenhouse.

Discover for yourself what Herb Caen referred to as "the best kept secret in the Bay Area."

At night, a grove of towering redwood trees growing through the pavement block out all light from the so-called “Dark Park” of Madrone Avenue.

George Lucas donated this park to honor the birthplace of his two biggest movie franchises.

The haunting ruins of Jack London's dream house.

After it was swallowed by a Georgian mansion, this medieval castle remained forgotten for centuries.

A devastating booze inferno poured through the streets, claiming several victims who drank it.

Amidst the bustling streets of Dublin, there is a hushed garden that is dedicated to "All those who gave their lives in the cause of Irish Freedom."

A nun spent 16 years painting the stunning Celtic mural that covers the interior of this WWI memorial.

Experience what life was like in Ireland during the Viking and medieval ages.

An Irish church where an 800-year-old mummy is reaching out of his coffin as if to shake hands.

Dublin's "Dead Zoo" serves as a window to Victorian museum design.