Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

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

Sitting on an Italian hilltop is this surreal fortress built by the mad inventor of electrohomeopathy.

This one-time health resort was used by aristocrats around the world.

The world's oldest known salt mine.

An Austrian house of bones filled with hundreds of intricately painted skulls.

This "mathematical tower" was an observatory, early skyscraper, and place to reflect on all of nature and the cosmos.

Ride a dragon train into a world of dwarves.

Relive a Polish uprising via an enormous, century-old cyclorama.

The silly symbol for an underground protest group is now scattered around the city.