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

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

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

This Manchester laundromat is hiding something.

The oldest inn in England served brew to the crusaders.

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

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

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

Created hundreds of years ago, the magical follies and landscapes at this park were almost lost to time before being restored.

Once thought to be the mysterious work of a witchy prophetess, a well with unusual properties turns objects into "stone".

Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

A fantastic castle rumored to be the birthplace of King Arthur.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

A kaleidoscopic warehouse-maze of handmade neon signs.

The longest hedge maze in the world.

A curious collection of mechanical moving figures.

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

Long abandoned underground complex to keep royals safe from a nuclear war that never came.

A familiar otherworldly creature guards this 12th-century Scottish abbey.

Large-scale contemporary artworks tower over fields and lurk in forests around a Jacobean manor house.

There are plenty of wonderful panoramic vistas in Edinburgh, but not many are hidden smack in the middle of the Old Town.

This stately estate house features a tower covered in a bright, modern mural.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.