A beautiful ruin of a 14th-century Plantagenet castle built by a medieval mercenary.

The rose garden in Regent's Park where Pongo and Perdita met for the first time in Disney's "101 Dalmatians."

A friendly pub with a sordid past in cock fighting.

This long-hidden space above Westminster Abbey now displays the battle gear of the legendary King Henry V.

Although it appears ancient and mysterious, the quirky folly was actually built 200 years ago by an eccentric estate owner.

This macabre monument atop an ancient well gives a nod to a brutal episode in Scottish clan history.

You'd never know the houses at 23-24 Leinster Gardens were fakes—until you see the train tracks on the other side.

Fantastically decorated underground chambers built in the 1760s.

A perilous medieval road leading right into the sea.

The remains of an ancient Roman teenager are memorialized at the base of a modern London landmark.

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

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

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

A verdant 17th-century-style garden hidden along Edinburgh’s Royal Mile.

A museum wholly devoted to juvenescence.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

The sculpture is made of more than 100,000 knives collected to raise awareness about violence.

A beautiful Greco-Roman structure houses a well once believed to have healing powers.

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

During this Shetland Islands celebration, hundreds of torch-carrying "guizers" lead a procession to burn a viking longboat.

Summer in Scotland begins with a spectacularly wild and colorful event rooted in ancient pagan traditions.

This abandoned asylum in Wales might look haunted, but it's still beautiful.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

This video store is a horror buff's dream.