The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

These ornate arches show how the course of the River Thames has changed.

Tucked away behind the mansions of Mayfair, this picturesque garden is a hidden London treasure with a spooky past.

Black cat statues guard this temple-like Egyptian revival factory.

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

These precariously placed ruins harken back to a 13th-century castle.

This medieval sanctuary's tree-framed door looks like a portal to a mythical realm.

A rampant horde of demons smirk and snarl at visitors to this church, home to a rare complete set of medieval-era stained glass windows.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

This tangled English forest looks like something right out of a fairytale.

"Respectful to the dead, safe and sanitary to the living, dedicated to the Genius of Memory..."

Islanders once used this dramatic, otherworldly landscape to hide their cattle from Viking raiders.

Tiny effigies of the victims of Edinburgh's famous Anatomy Murders.

Once considered one of the country's finest motte and bailey castles.

The ruins of this gorgeous clifftop castle look like something from a fantasy novel.

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

Amazing and mysterious Neolithic settlement on Scotland's Orkney Islands.

Order bagels and lox from an iconic Jewish delicatessen with nearly a century of history behind it.

A rare survivor from the age of plagues.

Baked in 1898 and still almost flawless, this floral masterpiece is considered the world's oldest complete wedding cake.

A historic pub with traditional Irish cuisine, fine drinks, and a paranormal past.

It's possible to walk inside one of the largest Neolithic tombs in Britain.

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

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