A Roman spa buried deep beneath the City of London.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

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

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

Hidden beneath the streets of London is a secret subway that only carried mail.

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

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

One of the foremost Sherlock Holmes collections is hidden away at a Toronto library.

Lost subway station nestled beneath Toronto's busy commuter line.

This third-generation institution is one of the last in London that still cures its own salt beef for epic sandwiches.