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

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

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

There's an exclusive Beefeaters pub hidden in the Tower of London.

An architectural oddity hides in plain sight on this iconic London bridge.

A discarded movie prop that was the original monolith for "2001: A Space Odyssey."

A defensive structure built during the Hundred Years War has remained useful in one way or another for nearly 700 years.

An impressive armored bronze effigy marks the tomb of one of the medieval era's greatest warriors.

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

This neon landmark has been posing this deadpan question to follicly-challenged Dubliners for over 50 years.

An enigmatic monument to the Irish revolutionary who plotted an uprising against British rule.

Eastern Canada's ocean playground.

Memorial to a beloved puppeteer as well as all street performers.

The statue of John Harvard isn't actually John Harvard—or even, technically, the founder of the school.

A beacon atop a downtown building provides Bostonians with weather forecasts and baseball news.

Painstakingly built dioramas sit unnoticed in a Boston office building.

Statue commemorating the use of ether in anesthesia.

The Boston square dedicated to the dark poet who was born nearby.

A men’s restroom became a sandwich shop.

Millions of numbers carved in glass represent the tattoos forced upon victims.

The site of Paul Revere's historic two lantern warning.

"Mock all and sundry things, but leave the saints alone."

A collection of full-size movie monsters opened to the public.

Statue in Salem of the woman who starred as the witch Samantha in the sitcom "Bewitched."