The ruins of an 800-year-old monastery boasts the tallest round tower in Ireland.

A rocky Irish outcropping with a history of wealth, conflict, and ruin.

This ancient Irish religious site is covered in ancient carvings, many of which have barely aged.

One of Ireland's most infamous prisons for rebels including men, women and children.

One of the most popular megalithic sites in Ireland stands as a humbler version of Stonehenge.

The ancient tomb acts as a calendar that keeps perfect time.

An Irish church where an 800-year-old mummy is reaching out of his coffin as if to shake hands.

This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

This lovely little burbling creek is actually a deadly waterway that has dragged down everyone who ever set foot in it.

It is said the legendary wizard once lived in this sea cave beneath Tintagel Castle.

In Twickenham sits a small whitewashed castle that inspired Mary Shelley's 'Frankenstein.'

Stonehenge has nothing on Castlerigg’s views.

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

Fantastically decorated underground chambers built in the 1760s.

These stark white cliffs were spat up by the sea and are slowly being retaken by it.

This foolish Victorian sea fort was converted to a deluxe hotel.

Besieged by war, this castle ruin has crumbled into a peaceful picnic spot.

The largest stone circle in the world has ended up bringing up more questions than it has answered.

One of the oldest and certainly best preserved Cistercian abbeys still in existence.

Western Europe's only representation of a Roman goddess still in its original location sits in an unassuming park.

A 6th-century stone lies at the site of the mythical battle waged between King Arthur and his nemesis Mordred.

These ancient sunken lanes were naturally tunneled into the soft ground by countless footsteps.

Fascinating town where normal life interfaces with the occult.

The largest cave chamber in Britain—big enough to fit a whole cathedral inside.