This Roman amphitheater is said to be King Arthur's legendary Round Table.

Overlooking a Scottish loch, this beautifully crumbling castle once inspired a poem by William Wordsworth.

A perilous medieval road leading right into the sea.

With lush plants and flowers, huge trees, ponds, and hidden monuments, this place feels a bit like discovering Narnia.

These ancient sea caves hold Britain's highest concentration of Pictish rock carvings.

Modern megaliths form this work of cosmic, Celtic landscape art.

The quiet field that inspired one of the most famous songs of all time.

The oldest residential street in Europe also features an optical illusion.

This unchanged Victorian park is rumored to have been the inspiration behind Peter Pan's Neverland.

St. Mary's Asylum was isolated and abandoned before being converted into a Bed and Breakfast.

These ruins witnessed the final gathering of the failed Jacobite Rebellion.

Every birth, death, and marriage is recorded in these color-coded leather-bound books.

The oldest continual pilgrimage site in Britain was supposedly created by a gruesome beheading.

Human-made caves excavated to hide a secret society of wealthy pagans.

The U.K.'s first underground railway line is now a lively thoroughfare for runners and cyclists.

These lovely Turkish-styled baths were brought back to life after winning a reality show competition.

The "Bridge Over the Atlantic" lets you cross the waterway in mere seconds.

An engineering error ensured this cavernous 350-foot-long subterranean thoroughfare was never used as intended.

A meandering boardwalk across the bogland leads to a "stairway to heaven" with sublime views.

This beautiful "lagoon" is actually a toxic soup filled with cars, carcasses, and trash. When warnings couldn't stop people from going for a dip, the town dyed it black.

This giant wooden treehouse within a sprawling garden has its own eatery.

A harem-inspired Moorish fantasy design in a Victorian-era Welsh castle.

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

The abandoned transportation hub hides within the Glasgow attraction it once served.