This chain of artificial lakes was an ideal test ground for the aircraft that would carry the "bouncing bombs" used by the WWII "Dambusters" squad.

Some of England's last cave dwellers lived and worked within this huge cave.

A magnificent winding road through a steep valley, with deep natural caverns at the bottom

This 47-story "M" needed 20 years to be completed

Legends surround this natural rock formation that looks like a Moorish king wearing a crown.

This magnificent tourist cave, with the highest ceiling of any in Spain, was once an anti-fascist arms dump and war factory and is now a concert venue

Legend has it the famous Robin Hood would attend mass at this 12th-century Cistercian abbey in Sherwood Forrest.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

A gorge full of caverns where early humans lived alongside cave hyenas, giant mammoths and wooly rhinoceroses.

The whimsical twist of this spire was either caused by the Devil, an unexpected virgin, or lead.

This unique sculpture of a steelworker is hidden amid the trees of Sheffield.

One of the last remnants of the Bessemer process that revolutionized steel production during the industrial age.

In the 19th century, this pit housed a fully grown black bear for the entertainment of visitors. Today there is a sculpture in tribute to the poor creature.

This sculpture marks the spot where one of the greatest Roman rulers was proclaimed emperor.

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

A century-old tradition has culminated in a small but singular collection of feline effigies.

The remains of an ancient bathhouse sit inside this aptly-named pub.

This network of narrow, medieval passages has the most delightful name.

This popular square's history as the former site of a church is right beneath your feet.

Makers and sellers of the original and finest York Ghosts.

One of the shortest streets in York has an especially odd name.

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

An incredibly well-preserved piece of ninth-century Viking poop.

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