The largest cave chamber in Britain—big enough to fit a whole cathedral inside.

A cluttered and astounding collection of antiquities and curiosities.

An small and easily overlooked archaeology museum chock full of Egyptian artifacts.

Charles Babbage's proto-computer, painstakingly brought to life.

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.

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

Where Aleister Crowley attempted to seize the Hermetic Order of the Golden Dawn in a mask and a kilt.

Fantastically decorated underground chambers built in the 1760s.

An 18th century monument regularly tagged with unsettling graffiti referencing a 1940s unsolved murder.

Eclectic final resting place of the controversial explorer.

It is against the law to obstruct the view from the top of this English burial mound.

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

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

One of the oldest trees in Britain may have been witness to some of the country's formative moments.

A historic house devoted to the teachings of a 1700's prophetess and her mysterious box of revelations.

One of the tallest maypoles remaining in England in one of its smaller villages.

A petite castle folly in the English countryside.

"The Most Wonderful Wonder that ever appeared to the Wonder of the British Nation."

Museum celebrating the history of computers, especially their role in codebreaking.

Over 100 years ago this pyramidal holding cell was reserved for rowdy drunks but now only offers five minute sentences.

Hidden in plain sight on a pair of Manhattan subway tunnels are a pair of public instruments that sing to each other.

In its day this historic fort held 100 cannons pointed in almost every direction to protect New York.

Possible relics of the ancient Roman city are hidden in this restaurant's façade.

This curved Manhattan building was built to house the opulence of John D. Rockefeller's oil empire.