The 2,000-year-old beam is tucked within the pedestrian entrance to the old London Bridge.

This fantastical waterfall is hidden in a cave located in a cracked cliff.

Medicinal spa created with the discharge from a geothermal energy plant.

This stunning concert hall has become a symbol of Iceland's national recovery.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

A musical instrument played by the sea.

Macabre astrological automaton clock dating to the late 1400s.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

Pop culture has helped to keep this iconic British building from being destroyed.

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

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

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

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

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

This small museum in a former church crypt contains artifacts of the Elephant Man, Jack the Ripper and Florence Nightingale.

A little sculpture with a large wardrobe.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

The last bastion of Roman presence north of the Alps looms over a German town.

This 600-year-old home seems to defy physics.

World's largest barrel containing an inn.