Also known as Rye Castle, this 13th-century fortification later became a prison and held one of Rye's most famous criminals.

400-year-old garden, restored to beauty.

The largest greenhouse in the world is home to over one million types of plants.

Britain's oldest and biggest hole in the ground.

The world's largest collection of witchcraft regalia.

A metal tree emits eerie, melodic notes on top of Lancashire's Crown Point.

The first island in the world designated a light-pollution-free astronomical observation point.

Northern Ireland's church-turned-skate park.

Museum about life, death, and cannibalism in the Stone Age.

A 200-year-old prison that now houses a peculiar crime museum.

65 million-year-old chalk outcroppings mark the end of the Jurassic Coast.

A village on the east coast of England that has almost completely eroded into the North Sea.

Below a historic English market town lies a secret underground city complete with kitchens, laundries, storerooms, and an underground lake.

Huge concrete structures designed as an early warning system for Britain to detect enemy aircraft.

The biggest and deepest Cold War bunker open to the public can be found in southeast England.

A 1970s resort city now stands abandoned, caught in the middle of a divided island.

Fantastically decorated underground chambers built in the 1760s.