The attic of a four-century-old canal house hides a clandestine church.

A church of bones, decorated with 40,000 human skeletons.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

This abandoned Greek island was the last active leper colony in Europe.

A Trabant car, a kangaroo statue, and a plethora of plants take over this abandoned-factory-turned-bar.

A dream-like maze full of strange art, surreal spaces, and fantasy landscapes to get lost in.

This medieval castle was painted pink as part of a now-abandoned children's theme park.

A UFO-shaped event building originally intended to be a science museum showcasing the future.

A church filled with the bones of hundreds of virgins martyrs—or so they say.

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

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

A haunting collection of the vanished and disappearing natural world.

A curious collection dedicated to human and animal anatomy and pathology.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

Increasingly decayed figures stand as a powerful reminder of the human costs of Czech Communism.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

Synagogue built from the stones of Solomon's temple contains the golem of Prague.

The hidden lair of an alchemist rediscovered in a 2002 flood.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

This artificial cave looks like something out of a fairytale.

A random tree outside a Budapest hotel has become a DIY shrine to the late singer.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.