Monty Python fans will recognize this abandoned mine as the Cave of the Killer Rabbit of Caerbannog.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

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

A memorial for public executions that dates back to the 14th century.

At almost 1,000 years old, this is the oldest known door in all of Britain.

These wire animal sculptures commemorate the exotic inhabitants that once called the Tower of London home.

A historic hill of tall tales, with one rather special tree.

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

The commemorative stone column conceals a secret laboratory.

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

The 2,000-year-old beam is tucked within the pedestrian entrance to the old London Bridge.

The first tunnel to be dug beneath a river, repurposed as an art and museum space.

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

A plaque hangs near the execution place of the Scottish Independence leader famously depicted in "Braveheart."

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

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

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

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

Where condemned pirates met their grisly end at the gallows on the River Thames.

Pop culture has helped to keep this iconic British building from being destroyed.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

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