St Bartholomew's Cathedral in Frankfurt, Germany

Ghosts of empires past. It's Halloween!

Forget the fog machine. Frankfurt, Germany, has something far more effective: a Gothic cathedral with a tower that looks ready for a midnight séance. St Bartholomew's Cathedral, seen here, has the medieval silhouette Halloween practically ordered for itself. But the festival's own history is even stranger.

Halloween was already perfecting the spooky atmosphere long before anyone invented fun-sized chocolate bars. Some of its traditions have been linked to Samhain, an ancient Celtic festival marking the harvest season's end and winter's beginning. Tradition held that the boundary between the living and the dead blurred then, allowing supernatural beings to wander our world. People responded with bonfires, offerings and disguises designed to blend in with the otherworldly crowd.

The Christian calendar later added All Saints' Day on 1 November and All Souls' Day on 2 November. The night before All Saints' Day became All Hallows' Eve, eventually Halloween. So while St Bartholomew's supplies the Gothic backdrop, Halloween brought ghosts, disguises and supernatural drama. Honestly, the festival came prepared.