Catacombs turned marketplace.

The largest of London's subterranean rivers and once a mad, bad center of London life.

A historic house left in "dramatic still life."

Hear the quietest sound from across the dome.

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

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

A special shop catering to the needs of things that go bump in the night, and also helps kids become writers.

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 vast overgrown cemetery, once known as one of London's "Magnificent Seven."

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

Rebuilt remains of a temple to Roman god Mithras.

The curios of pharmacist and collector Henry Wellcome.

One part local history, 99 parts gruesome haunted house.

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

A hands-off space for graffiti artists to hone and display their skills.

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

A tongue-in-cheek arcade where the games are based on everyday life.

An unusual round church in London with a Templar past.

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

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.

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

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