A steampunk-styled three-floor factory churning out art, activism, and electronic beats.

Walk through Czech history in Prague's largest graveyard.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

The first museum in the world devoted to sexual gadgetry.

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

Countless grotesque faces stare out from this eerie Prague art wall.

Macabre astrological automaton clock dating to the late 1400s.

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

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

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

An abandoned Jewish sanatorium is tucked within the woods of Poland.

Disturbing works of outsider art, carved from whole logs.

On this Polish road, an optical illusion makes cars seem to roll uphill.

This hilltop ruin is of the hundreds of stone columns built in tribute to the first German chancellor.

A World War II torpedo launch station abandoned off the Polish coast.

This imposing 20th-century castle was abandoned before it was ever completed.

Deep in a Polish forest, this collection of Iron Age megaliths still holds onto many of its ancient secrets.

What was once an underground Nazi city is now Europe's largest bat reserve.

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

Once a giant gingerbread factory, this space now hosts exhibits and workshops on the historic treat.

A haunting deserted hotel is a favorite with artists and photographers.

A mysterious structure left behind on the Polish mountainside, sometimes called "Hitler's Stonehenge".

A peculiar family mausoleum built by a German nobleman captivated by the occult.

This 700-year-old structure is one of the most unique architectural and historic monuments in Gdańsk.