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

Abandoned railway line circling the city of Paris.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Folklore and history carved into Brittany's coast.

An abandoned beach resort in Normandy reclaimed by artists.

A remote hilltop covered in giant monoliths haunts the Brittany countryside.

Massive puppet-automaton machines created by French artist collective Machines de l’Ile.

Beautiful carved tunnels.

Personal garden filled with mosaics made of recycled garbage.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

A castle-like sea fort from the 17th century is now a museum to oyster farming.

This historic black and white monastery is one of Bulgaria's architectural jewels.

An ancient Thracian city where fire rituals were practiced on the largest cult altar in Southeast Europe.

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

An abandoned saucer-shaped monument in the Bulgarian mountains.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

Romania's only crater lake with water as pure as if distilled.

No one knows who built this strange cave of worship or exactly why.

A muddy alien landscape that is home to rare species of exotic plants.

This eccentric folly house was designed by Romanian thinker Bogdan-Petriceicu Hasdeu, with a helping hand from his deceased daughter's spirit.

Collapsing castle on the Hudson river was once the storage site of military surplus business.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

Hidden in an Italian forest is a completely homemade amusement park that has taken a lifetime to create.