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

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

A sculpture outside London's oldest cathedral honors the Mohegan chief who died while petitioning the king.

A unique tribute to the millions of animals who served and died for the British military.

Originally built for London’s cab drivers, this bright green hut now serves anyone a hot drink or meal.

The fierce beast perches atop a pedestal marking where the historic City of London gates once stood.

A statue of the legendary Celtic warrior queen who fought the Roman invaders stands in one of the cities she once destroyed.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

One of the famous Czech artist's lesser-known Prague installations appears to be a glowing fetus affixed to a drainpipe.

This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

The slender brass strip in Prague's Old Town Square was used to tell time from 1652 to 1918.

Monument to a suicide protesting the Soviet invasion.

This automated sculpture of two men peeing will spell out text messages with their micturition.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Macabre astrological automaton clock dating to the late 1400s.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

A sculpture serving as an homage to Pope John Paul II.

What looks like a suicide in progress is actually a statue of Sigmund Freud.

The sculptor was instructed to add “stallion attributes” to the general's bronze mare.

One of the world's tallest Ferris wheels takes visitors high above Las Vegas in a spinning party room.