A relic of Victorian grandeur hides beneath a busy South London road.

This tiny island featuring 9th-century Viking ruins is only accessible at low tide.

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

The largest oak in England is said to have been the hideout of Robin Hood and his Merry Men.

The Stonehenge of Wales is one of the grandest neolithic dolmens still in existence.

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

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

Climb this overlooked gem's spiral staircase and you'll be rewarded with spectacular views of Glasgow.

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

Follow the original medieval paths that wind through this intriguing section of the city.

This allegedly haunted 16th-century tower house-turned-museum exhibits thousands of spectacular objects.

The remains of a grand castle that may have inspired Bram Stoker's Dracula.

J.R.R Tolkien, C.S. Lewis, and other "Inklings" met at the Oxford pub to discuss the now legendary fantasy stories they were writing.

The ruins of an 11th-century Norman castle with a rare, perfectly circular shape.

A remarkably well preserved tower dating all the way back to the Iron Age.

The oldest inn in England served brew to the crusaders.

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

Three bridges straddle a stream, one stacked upon the other.

Dating back almost 400 years, the oldest public collection library in the United Kingdom was once the study hall of Karl Marx.

A red sandstone freestanding monolith rises out of the sea in northern Scotland.

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

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

England's oldest surviving hedge maze has been confusing visitors for over 300 years.

The names Lúthien and Beren can be found inscribed on the shared grave of the famous writer and his beloved wife and muse.