Museum dedicated to "the man who moved the Earth."

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

Poland's oldest surviving university building holds a wealth of historic science instruments including some used by Copernicus.

An abandoned Nazi explosives plant founded by the inventor of dynamite is now an underground museum.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

An underground city of salt.

Tucked in the back of this amazing antique store is an important piece of medical history.

A terrific purveyor of natural history objects and curios.

The mummified right fist of a 1,000-year-old saint-king sits inside an ornate golden reliquary.

A museum in the childhood house of a medical pioneer.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Once the home of a hermetic monk, this cave now houses a small church.

Museum dedicated to the terror regimes of Hungary.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

The mass grave of the 27 victims of the "Vampire of Hanover."

A spitting ode to a German serial killer.

This jail which was in service for over a century is now open for curious visitors.

Behold the rickety wooden glory of the world's oldest operating roller coaster.

This hidden gem of a garden has one of the only surviving Victorian ferneries in America.

Instruments, apparatus, and rare books all relating to chemistry and its related sciences.

Board a mine car and descend the #190 slope 300 feet underground into the Clark Vein of coal.