The commemorative stone column conceals a secret laboratory.

The ritual has been performed uninterrupted for nearly 700 years.

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.

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

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

Never actually a tree at all, this spot was the site of London's public hangings for nearly 600 years.

The last four extravagant street signs of London's historic banking street.

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

An eccentric 18th century naval officer built a ship's quarterdeck on his roof, the inspiration for Mary Poppins's "Admiral Boom."

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

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

This secluded walkway overlooks a magnificently wild London green space.

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

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

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

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

This legendary stone is of unknown origin, and throughout history has been a literal touchstone for British leaders.

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

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

London's old-school healing garden.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

The sixth of London's "Magnificent Seven" cemeteries, and a source of unlikely inspiration to Beatrix Potter.

Scattered throughout London are ancient remnants of the city's former bounding wall.