Graffiti from the 16th and 17th centuries cover the walls of this part of the Tower of London.

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.

This one has sailed five times as far as Sir Francis Drake's famous ship.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

After nearly 60 years, there's still a bear at Paddington Station looking for help.

A statue marks the exact spot where The Boy Who Never Grows Up made his first literary appearance.

The secret wartime bunker built on the platforms of an abandoned Tube station.

Once designed as the entrance to Buckingham Palace, this structure was later relocated and stands as a victory arch.

This once-controversial and slightly confusing statue of Achilles was built out of captured cannons.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

A neighborhood church's unusual abstract stained glass was the final project of avant-garde artist Jean Cocteau.

In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

This life-size bronze statue remembers the tallest recorded human in his Illinois hometown.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

Quirky water tower advertises the long-gone Brooks Tomato Products Co.

This private residence was the template for one of the most beloved television homes of all time.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

Shoot for par over the bodies of the dead on this cemetery-cum-golf course.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

Guns that have been defending San Francisco since 1904.

A working model of the entire San Francisco Bay and much of the Sacramento River Delta, complete with regular tides that change every 14 minutes.