Northern Ireland's Brobdingnagian stepping stones.

A house of bones — but nobody is quite sure to whom they belong.

Surreal riveted sea forts once protected the Kent shores from German attack.

A 550-square-meter micro-nation off the coast of Britain.

The sculptural remains of the last home of a legendary Dada artist.

Famously misunderstood wonder of the ancient world

A village on the east coast of England that has almost completely eroded into the North Sea.

The anatomical-pathological collection of a man who changed surgery.

The decaying ruins of Wales' first asylum for the mentally ill.

Europe's second largest ossuary wasn't discovered until 2001.

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

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

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

Ancient cliffs resembling a kilt on Scotland's second largest island emit an entrancing sound.

A metal tree emits eerie, melodic notes on top of Lancashire's Crown Point.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

A musical instrument played by the sea.

Huge concrete structures designed as an early warning system for Britain to detect enemy aircraft.

A visionary precursor to the Internet made of index cards.

A giant pineapple, a symbol of hospitality, and an amazing vacation rental option.

A petite castle folly in the English countryside.

Fantastically decorated underground chambers built in the 1760s.

Hydraulic systems in an ancient underground Iranian city.

Gothic tower mentioned in Thomas Hardy poem "The Channel Firing."