Hidden behind a wall for decades, this masonic lodge was only rediscovered during renovations.

The sixth of London's "Magnificent Seven" cemeteries, and a source of unlikely inspiration to Beatrix Potter.

Scattered throughout London are ancient remnants of the city's former bounding wall.

The fountain marks the area where hundreds of accused witches were burned at the stake.

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

The remains of Crystal Palace Great Exhibition of 1851.

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

A 18th century graveyard and its astonishing cortege of macabre iconography.

A church that bred legends, and served as an inspiration for the Da Vinci Code.

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

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.

The site of London's first coffee house has been serving refreshments of one kind or another for 360 years.

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

A mysterious artist-run cabinet of curiosities and library.

This series of Scottish caves has no clear purpose other than baffling historians.

Catacombs turned marketplace.

Remnants of a Victorian garden feature sitting in public woodland.

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

"Respectful to the dead, safe and sanitary to the living, dedicated to the Genius of Memory..."

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

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

Hear the quietest sound from across the dome.

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.