A 2000-year-old Roman amphitheater lies just below Guildhall Yard.

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

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

London's smallest police station is barely the size of a phone booth.

An alleyway plaque is all that remains of the independent Texas' envoy that forgot to pay their rent for over a century.

Eighty million natural history specimens call this gargantuan museum home.

Remnants of a Victorian garden feature sitting in public woodland.

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

The gloomy ruins that inspired Bram Stoker to bring Dracula to life.

A historic house left in "dramatic still life."

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

Hear the quietest sound from across the dome.

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.

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

The curios of pharmacist and collector Henry Wellcome.

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

A student driver's nightmare.

An unusual round church in London with a Templar past.

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

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

Northern Ireland's Brobdingnagian stepping stones.

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

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