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

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

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

A tiny village in Wales claims the name of a noble medieval hound slain for a crime he didn't commit.

These medieval tunnels provided water to the city above through centuries of civil war and plague.

Sometimes an island, sometimes a rocky outcropping connected to the world by a tiny suspension bridge.

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

World's largest working waterwheel has been around for over 150 years.

The remnants of a Gilded Age elegance preserved in the middle of a stark modern tower.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

A million and a half tons of earth were used to create one of the world's largest land sculptures.

Built in 1911, the Tees Transporter Bridge is one of only six transporter bridges still in operation.

The oldest inn in England served brew to the crusaders.

A giant white horse drawn on an English hillside may not have been intended to be a horse at all.

Famously misunderstood wonder of the ancient world

This historic home of the author of Lawrence of Arabia, has a history of literary celebrities and monogrammed sleeping bags.

The oldest working mechanical clock in the world.

A historic Georgian building and warm springs.

Once the largest unsupported dome in the world, beating out the Pantheon and St Peters in Rome.

This 17th-century street hidden beneath Edinburgh was once a breeding ground for the black death.

A sweet symbol marks the place where torturous executions were once carried out.

This evocatively named natural crevasse was created by a torrent of water that smashed right through a granite deposit.

Ironically this massive termite is the mascot for a company that is acclaimed for killing his kind.

The 340-year-old house that inspired the classic Nathaniel Hawthorne novel.