An existential riddle in the world's largest ancient castle.

A crucified and bearded female saint.

Street artists transformed an abandoned air vent into the beloved Star Wars robot.

An old asylum graveyard that's been abandoned for half a century attracts those seeking a dark thrill.

Buried five stories underground, this Soviet bunker is packed with gas masks and Cold War paraphernalia.

A Jenga-style cylindrical tower of books that appears to go on forever.

An exquisite panometer representing Dresden as it was from 1695 to 1760.

To the great disappointment of doomsdayers, this codex merely contains records of the Moon and Venus.

Nestled on the banks of a river in Nuremberg is a small museum that was once home of the city's official executioner.

This lurid German fountain plots the sad course of marriage from dating to death.

This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

The mysterious remains of a martyred teenage saint are venerated inside a small country chapel.

Seaside ruins of a settlement that date back to the first century B.C.

This chest hospital with a dark, haunted past serves as a fitting set for horror films and a paradise for ghost hunters.

This abandoned mansion has a window for every day of the year, and is a temple for ghost hunters.

This Navarrese cave's history of witchcraft and pagan ritual is not just embraced, but recreated each year.

A Spanish forest is filled with mysterious stone carvings.

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

Wonderland replication in progress by one persistent man.

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

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

This cemetery features modernist statues as strange as its name.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.