Three large boulders covered in mysterious carvings and graffiti.

The castle that provided the setting for much of 'Monty Python and the Holy Grail' is now a pilgrimage site for fans.

A public art project to commemorate a tumultuous period in Derby's history.

A pair of stone circles positioned on the bank of the River Esk.

Believed to be the smallest castle in Europe.

This extraordinary Viking artifact has traveled throughout the city.

This courtly monument celebrates an influential comedian who turned taking the piss out of the powers-that-be into an art.

One of Ireland's lesser-known megalithic structures.

In the ruins of Glastonbury Abbey lies the alleged resting place of the legendary king.

Believed to be an execution site used by King Arthur after he was embarrassed.

Though this large circular site is now named for the legendary king, its history dates back to the Neolithic era.

This supermarket offers shoppers a window into the past alongside their groceries.

A diminutive, thousand-year-old church believed to be the smallest in Ireland.

Named for its similarity to the tip of a violin's bow, this striking formation was created by millions of years of erosion.

A pair of stones embedded in an Edinburgh street memorialize one of the city's last public hangings.

An ancient stone with mysterious origins stands in a residential neighborhood.

A lone pole once used to display a man's corpse now stands empty, but the memory remains.

Also known as "Robin Hood's tree," this tree became a famed location along Hadrian's Wall before it was cut down in an act of vandalism.

Ruined castle with subterranean vaulted Goblin Ha' or "Goblin Hall."

The only place where can you share a seat with the bums of the Fab Four.

Led Zeppelin wrote some of their most iconic songs at this little 18th-century Welsh cottage.

Cascading waterfalls mark the gateway to the ancient burial place of Clan Macnab.

Possibly the oldest living thing in Europe, more likely a pagan survivor.

On this wooded path, a stained-glass window creates a spellbinding forest cathedral.