Stroll through retro Paris while shopping for old postcards and discarded doll heads.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

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

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

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

Two awe-inspiring globes from the reign of the Sun King hang from the ceiling of France's national library.

Notorious artist squat renovated into legal studios.

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

The risqué mixed-media sculptures are supposedly a metaphor for Czech politics.

An abandoned mine now resembles a post-apocalyptic landscape of derelict buildings and blood-red pools of water.

Considered the birthplace of the Copper Age and Bronze Age, the river is tinted red from 5,000 years of mining.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

This narrow path was cut right into a French mountainside to feed the country's early naval expansion.

"Alleys of Stone" form natural mazes in Spanish natural park.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

The studio of Catalonia's most famous theatrical designer remains exactly as he left it.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

Mountain where Jesus was first tempted by the Devil.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

A beautiful but toxic fountain of mercury.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

A narrow strip of land is home to the tallest migrating dunes in Europe.

An old hill fort covered in over 100,000 crosses is a symbol of Lithuanian nationalism and beliefs.

Non-profit time travel mart sells goods you would need for a trip through the fourth dimension.