A seven-century-old jail tells a not-so-pleasant history of crime and punishment.

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

This centuries-old gothic monster has been converted into a sprawling, glossy bookstore.

This impressive collection of rare books on ancient mysticism inspired author Dan Brown.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

A curious collection dedicated to human and animal anatomy and pathology.

Museum preserving torture methods from the past.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

The world's only museum devoted to the wonders of fluorescence.

A curious cave church carved into the face of a cliff.

Enigmatic tombs and cave dwellings on the outskirts of a rural village.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

A hidden tunnel of bones in one of Malta's oldest churches.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

Things aren't quite what they seem at this mind-bending museum.

Museum deep in the catacombs of St. Michael the Archangel Church is explored by touch, sound, and smell.

One woman's lifelong collection is on display in this unassuming house on an Icelandic fjord.

This elderly couple's hand-picked collection of rare gems is one of the finest in all of Iceland.

The oldest hall in Iceland was written of in the Sagas and features a centuries-old escape tunnel.

The Arctic Circle runs through this isolated spot north of Iceland.

This collection of unique liquids allows visitors to wander the waters of Iceland's glaciers.

Three million year old fossils are exposed for all to see on this Icelandic shore.

A formerly glacier-tipped volcano that inspired none other than Jules Verne.