Semi-precious Blue John stones have been mined in this cavern system for centuries.

There's a strange stone hoodoo towering atop a wooded hillside and no one is quite sure how it got there.

This landmark Victorian folly rewards visitors with spectacular views over the Peak District.

This mysterious hilltop collection of Druid carvings isn't quite what it seems.

A magnificent winding road through a steep valley, with deep natural caverns at the bottom

Some of England's last cave dwellers lived and worked within this huge cave.

As the highest point in the Mid-Atlantic range this stratovolcano offers spectacular views.

The mountaintop inspiration for Umberto Eco's "The Name of the Rose."

Giant, pink stuffed rabbit on an Italian mountain.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

Leveled by an earthquake, this Italian village is now preserved as a massive concrete art project.

Venice's "Island of the Mad."

Hidden in an Italian forest is a completely homemade amusement park that has taken a lifetime to create.

This half-finished "city of toys" was almost Italy's own Las Vegas.

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

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

An eerie, derelict amusement park in Berlin.

An unusual house built using an iso-elastic membrane.