Created as a "model concentration camp" to hide Nazi atrocities from the international community, this former camp-ghetto now holds a museum and memorial honoring the lives lost within.

Tall columns of volcanic basalt make up this improbable-seeming rock formation.

Underneath the city that invented pilsners are a series of historic tunnels that have been storing beer for centuries.

Enormous sandstone towers loom within a Czech forest.

The deepest sinkhole in Central Europe comes with a grisly tale and an unusual nickname: “The Stepmother Abyss.”

Bohemian paradise covered in majestic forests.

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

This former quarry is now a picturesque gorge that hides a sunken lake.

Europe's largest natural bridge has a 19th century royal chateau built into its side.

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

A church of bones, decorated with 40,000 human skeletons.

Dedicated to the "father of modern education," this museum documents the history of education in Czechia.

The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

The first museum in the world devoted to sexual gadgetry.

Walk through Czech history in Prague's largest graveyard.

Two stunning 17th-century libraries and a cabinet of curiosities.

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

An extraordinary house museum and cabinet of curiosities in the heart of Florence.

Overlooked amid the tourist bustle of Florence, this museum is dedicated to the craft of stone inlay.

The graveyard is filled with beautiful funerary art and boasts breathtaking views of Florence.

Secret refuge and museum of the Duke of Florence.

The oldest operating pharmacy in the world features 800-year-old recipes.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

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