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

Europe's second largest ossuary wasn't discovered until 2001.

The mystery of the Putim Ossuary involves a tricorn hat.

A museum of alchemy and a basement laboratory all housed in an ancient building in a Gothic tower.

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

A collection of anatomical samples from one of the first anthropologists to suggest that humans reached North America by crossing the Bering Strait.

A bizarre form of natural mummification was discovered in the church of this Frisian village.

Two gravestones clasp hands over the religious divide.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

A former plague hospital turned medical museum.

This small town in the Netherlands has no roads but instead, miles of canals and over 100 bridges.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

Italian poet Dante Alighieri is entombed in this small mausoleum in Ravenna, and his hometown of Florence has never been too happy about it.

This sword isn't waiting for a king to pull it out. It was placed there by a saint.

This museum is rotten with a century of wax medical deformities.

A three-shelf library serves as a memorial in the Jewish cemetery of Krems.

The resting place for anonymous victims of the Danube's dark waters.

This rare collection of human deformities displays fetuses with two faces, one eye, and "mermaid" legs.

A 200-year-old collection of oddities and medical paraphernalia.

A 16th-century horror show built in a lovely Italian garden.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

A famous burial ground with a history both grim and literary.

An small and easily overlooked archaeology museum chock full of Egyptian artifacts.