This plaque in one of London's oldest public hospitals commemorates the first meeting of two of Britain's most famous literary heroes: Sherlock Holmes and Dr. Watson.

The ruins of a church destroyed by both the Great Fire of London and the Blitz, now turned into a peaceful garden.

What might be the oldest living tree in London has survived fires, bombings, and estate agents.

The ground on which Shakespeare’s initial playhouse once stood.

Murals of the wild parties once held on the frozen River Thames.

An incarceration museum on the spot of possibly the oldest prison in England.

The ruins of a once-mighty medieval palace are hidden away in otherwise modern London

Only a few pieces remain of the structure that carried people and goods across the Thames for some 600 years.

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

The commemorative stone column conceals a secret laboratory.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

A lone medieval church tower marooned among the City of London's skyscrapers

A hidden treasure in London with a rich medieval history, and the resting place of many luminaries.

The bridge is a secret gallery of discarded gum that has been transformed into miniature masterpieces.

The barrel-made lookout from Shackleton's final ship is tucked away in the crypt of one of London's oldest churches.

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

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

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

A mysterious suspended hand greets unsuspecting visitors at the Tower of London.

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

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.

These former ticket office windows in London's underground now house pocket-size parks.

A quartet of tiled art pieces adorn the floors of this prestigious art museum.