This black shoreline is made up of exploded lava particles.

These picturesque Hawaiian falls are home to a rare species of fish that uses a special sucker to climb up cliffs.

This legendary urban waterfall creates a dazzling display of rainbows.

Hide from the tourist hordes in these relatively unknown, and unguarded lava caves.

This Viking gravestone carved in a rare runic style was dug up from a London churchyard.

Graffiti from the 16th and 17th centuries cover the walls of this part of the Tower of London.

This beautiful Victorian ironwork masterpiece was built to keep London from smelling like poop.

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

A network of concealed passageways lies within a busy London Underground station.

The cedar tree in Highgate Cemetery earned its title by accident.

A Roman spa buried deep beneath the City of London.

This historic London residence was once the womb of Scientology.

The secret wartime bunker built on the platforms of an abandoned Tube station.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

The Tudor-style cottage in the middle of the square is not quite what it seems.

A kaleidoscopic warehouse-maze of handmade neon signs.

The quaint little store that is said to have inspired a famous Dickens novel was only given its name after the book was released.

An small and easily overlooked archaeology museum chock full of Egyptian artifacts.

A clock designed to run with perfect accuracy for 10,000 years.

An eccentric 18th century naval officer built a ship's quarterdeck on his roof, the inspiration for Mary Poppins's "Admiral Boom."

Eclectic final resting place of the controversial explorer.

A hidden treasure in London with a rich medieval history, and the resting place of many luminaries.

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

Where condemned pirates met their grisly end at the gallows on the River Thames.