While not Turkey's deepest underground city, this subterranean redoubt is the largest.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Roman ruins top white travertine terraces formed by ancient hot springs.

This famous city eluded concrete detection until the early 2000's.

No one is sure what to do with this WWII shipwreck that sits at the bottom of the Thames, still loaded with tons of explosives.

This charming, narrow-gauge railway in the Thames Estuary is sometimes referred to as the "Train to Nowhere."

The grounds of this Jacobean estate contain one of the oldest mulberry trees in England.

The last working windmill in the U.K. that has eight sails.

Under a church hides a forgotten 13th-century ossuary containing the remains of around 2,500 people.

Home to Alan Turing, the cracking of the Enigma code, and Captain Ridley's shooting party.

The oldest of the three remaining bridges in England with buildings on top of them.

The world's first military tank was designed in this English city amid the stalemate of WWI trench warfare.

A 600-year-old mini shrine guarded by a sword-wielding knight hides in a crumbling cliff face.

The little-known second castle that William the Conqueror built in York.

The last fully working Victorian Turkish bath in England.

A Reformation-era fiery figurehead once denoted this location as a print shop.

Makers and sellers of the original and finest York Ghosts.

Follow the original medieval paths that wind through this intriguing section of the city.

A deserted medieval village where bodies were once mutilated to prevent them rising from the dead.

This section of the Kennet and Avon Canal has been designated the same level of heritage protection as Stonehenge.

A rare labyrinth-style path carved into a historic hill.

This multicolored meandering masterpiece is Britain's longest bench.

A remarkable feat of Victorian engineering across the Firth of Forth.