The longest and tallest aqueduct in Britain can actually be sailed across.

In the U.K., a historic workhouse shines a light on the early, harsh treatment of the poor.

This English medieval castle is where King John died of dysentery.

The storied English village that pretended to be insane inspired NYC's nickname and the fictional namesake in the DC Comics universe.

The longest and steepest staircase locks in the United Kingdom.

An intriguing three-sided folly is a testament to one man's devotion to Catholicism and the number three.

The intended purpose of this unfinished Elizabethan building remains a mystery.

The sanctuary seems to either float atop the water or sink into the dirt, depending on the water level.

An engraved stone in a village church claims to be the grave of a minuscule folk legend.

According to legend, this is the site where a blind horse killed a local witch.

This lone tower casts an outstretched shadow over the site of a once-wealthy Knights Templar preceptory.

The near loss of the stately fireplaces at this medieval castle spawned some of Britain's most crucial historic preservation laws.

Single runway interrupted by a busy road that cuts across its middle.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

God's Saharan sandbox of wrath.

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

400-year-old garden, restored to beauty.

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

These "bridges" help confused bats cross the road.

This antique prison is a tourist attraction with a sordid past.

This remote castle was built to be a wealthy businessman's palace of vice but is now simply a historic vacation cottage.

A whimsical cottage from the 1300s with a preserved Victorian-era post office inside.

A 14th century castle built on the seat of a mighty giant.

The excellent acoustics of this natural amphitheater made it a popular preaching spot for the founder of the Methodist Church.