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

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

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

The anatomical-pathological collection of a man who changed surgery.

The curios of pharmacist and collector Henry Wellcome.

The quaint little store that is said to have inspired a famous Dickens novel was only given its name after the book was released.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

An unusual round church in London with a Templar past.

The site of London's first coffee house has been serving refreshments of one kind or another for 360 years.

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

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

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

This South London cemetery holds the remains of more than 15,000 people.

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

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

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

A kaleidoscopic warehouse-maze of handmade neon signs.

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

Saint Joseph was said to heal the deaf and blind, but it was a much smaller miracle that got him canonized.

A cemetery in Barcelona's Poblenou district is home to this touching funerary statue, which depicts death in the form of a winged skeleton.