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

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

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

The curios of pharmacist and collector Henry Wellcome.

A student driver's nightmare.

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

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

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

The longest hedge maze in the world.

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

360° views of the city plus five floors of optical illusions and hands-on science.

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

The most iconic structure in Scotland has been home to bishops, colonels, and Sean Connery characters.

Northern Ireland's Brobdingnagian stepping stones.

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

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

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.

The atmospheric road was never meant to be so creepy.

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

Famously misunderstood wonder of the ancient world

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

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