A marine aquarium with an astounding variety of fish hides in the basement beneath the famous Palm House.

The largest clown school in Britain offering accredited degrees.

A wonderfully eclectic Victorian aquarium lies in the basement of the Horniman Museum.

This beautiful deer park was built so King Charles I and his court could go hunting while escaping a deadly plague outbreak.

The world's oldest family-run magic shop is hidden beneath a bustling London thoroughfare.

This unique bridge curls up like a caterpillar to let boats pass and then unfurls again to span a small canal.

A relic of Victorian grandeur hides beneath a busy South London road.

Lovers proclaim their unbreakable bond by leaving their names on locks fastened onto the Shoreditch fence in East London.

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

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

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

Catacombs turned marketplace.

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

One part local history, 99 parts gruesome haunted house.

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

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

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

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

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

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.

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

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

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