"X" marks the spot of an echo chamber in the middle of a plaza.

One of the figures in this Celtic sculpture continues to puzzle archaeologists.

The childhood home of Earth's alien chameleon is a humble Brixton flat.

Two plaques commemorate the site of Shakespeare's first theatre.

The cedar tree in Highgate Cemetery earned its title by accident.

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

This 1920s Dutch barge is now a floating bookstore.

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

The monster at the center of the Darwin Center Spirit Collection.

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

This London plaque marks the spot where David Bowie's famous alien made his debut.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

An artistic tribute to the famous singer, just around the corner from where he was born.

A clock designed to run with perfect accuracy for 10,000 years.

The television series' iconic giant foot was borrowed from this classical painting.

A makeshift shrine to the late rock star is still kept up on the nondescript façade outside 1 Logan Place.

London's smallest police station is barely the size of a phone booth.

An alleyway plaque is all that remains of the independent Texas' envoy that forgot to pay their rent for over a century.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

Wedged between two buildings at the Great Ormond Street Hospital is this secret music installation.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

Rebuilt remains of a temple to Roman god Mithras.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

Banksy gives themself artistic license with this piece of London street art.