Northern Ireland's Brobdingnagian stepping stones.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

The atmospheric road was never meant to be so creepy.

This Italian-style temple replica has been threatening to fall off the Irish coast for hundreds of years.

The final resting place of soldiers' loyal canine companions.

A six-ton wedding present for the King of the Scots.

The most loyal of little dogs, or a Victorian era publicity stunt?

360° views of the city plus five floors of optical illusions and hands-on science.

A sweet symbol marks the place where torturous executions were once carried out.

This 17th-century street hidden beneath Edinburgh was once a breeding ground for the black death.

The handiwork of a underdog clockmaker who solved an impossible problem for an Empire, and forever revolutionized seafaring.

This elaborate Byzantine-style building was designed for a not-so-pretty purpose.

This hilarious English intersection is an automotive whirlpool.

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

Europe's largest prehistoric mound – burial site of a legendary king?

The granddaddy of English geoglyphs dates back to the late Bronze Age.

The first archaeological site discovered by aerial photography.

Famously misunderstood wonder of the ancient world

A giant white horse drawn on an English hillside may not have been intended to be a horse at all.

This well-preserved Cistercian Abbey in a romantic pastoral setting has inspired artists like the poet Wordsworth.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.