The ruins of this temple were later chosen by Pope Celestine V to found an abbey and a hermitage.

A holy stone inside this spectacular hermitage is said to have healing properties.

A fairy-tale-like forest that was sacred to Jupiter and Saint Anthony.

Shakespeare, David Bowie, Dr. Who, the Saxons, Druids and Romans are all claimed to have all made their mark on these massive man made tunnels.

This quaint mortuary chapel hides a stunning Celtic Revival and Art Nouveau interior.

The Neolithic megalith was one of the first archaeological ruins protected by the British government.

A Neolithic burial site built 1,000 years before Stonehenge.

One of the oldest trees in Britain may have been witness to some of the country's formative moments.

A subterranean playground in an abandoned slate mine.

A passage grave used in neolithic rituals.

A quiet country churchyard holds a monument to the last known sin-eater in England.

Near this allegedly haunted pub, you can find strong spirits on the rocks.

A writer's tiny retreat built from salvaged shipwreck timbers.

A beautiful drive through the foot of the Alps traces the path of 15th-century Turkish raids.

This abandoned Slovenian military barracks has become a punky-political art squat.

A crumbling World War I fort that is reached through a series of concrete tunnels.

An otherworldly alpine pasture with its own unique microculture that recalls Middle Earth.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

This massive subterranean fissure is known as the "underground Grand Canyon."

Man-made cave with enigmatic carvings, some say made by the Knights Templar themselves.

An architectural oddity hides in plain sight on this iconic London bridge.

Where condemned pirates met their grisly end at the gallows on the River Thames.