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

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

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.

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

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

Hear the quietest sound from across the dome.

Eighty million natural history specimens call this gargantuan museum home.

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

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

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

An unusual round church in London with a Templar past.

One part local history, 99 parts gruesome haunted house.

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

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

The pretty iron lamp is a reminder of the architecture underneath London's streets.

A massive volcanic plug is now a protected area that hosts a number of bird species.

The neon signs from Las Vegas' past find their final resting place at this unusual graveyard.

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

The museum chronicling a treasure hunter's dream, fulfilled.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

The blinking light atop the iconic landmark has been sending secret messages for decades.

Giant, friendly pelicans in Central London, the most unlikely of places.