A 1,215-foot tunnel transports pedestrians beneath the River Thames.

A 13th-century inn where the ill-fated King Charles I spent his last night of freedom.

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

Once a palace for the Archbishop of York, these 15th-century ruins now serve as a haunt for history buffs.

The undercroft is a spectacular example of medieval Cistercian architecture.

These barriers stand as stark reminders of Northern Ireland's troubled past.

In the ruins of Glastonbury Abbey lies the alleged resting place of the legendary king.

This hilarious English intersection is an automotive whirlpool.

It was once the base for a series of domestic terror attacks.

Washington's iconic carousel has a nice piece of Civil Rights history.

Modern commuters still pass through this 2,000-year-old Roman archway.

This mysterious hilltop collection of Druid carvings isn't quite what it seems.

Scattered throughout London are ancient remnants of the city's former bounding wall.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Iceland's tribute to its thankless civil servants.

One of the largest trees of its kind in California.

One of the few remaining carousels built by master amusement park carver Charles I.D. Looff.

One of the largest free-standing structures ever built, this dirigible hangar is now simply a giant skeleton.

A pair of large white marble lions guard this stretch of the Mojave Desert, and it is utterly mysterious how they got there.

This neolithic stone grave has been altered and restored so often its now more neo than lithic.

This Welsh village gave itself a ridiculous name in a publicity stunt a century ahead of its time.

A former fisherman's hut deemed too small for habitation is now a delightful tourist draw.

Picturesque ruins once held off mighty armies.

Abandoned ship reimagined as a street art canvas.