A labyrinth hides in plain sight at each of the city's 270 Tube stations.

This 1776 beacon on the coast of Wales is said to have a ghost called Raymond, the last lighthouse keeper.

After mysteriously refusing to surrender at the end of World War II this sunken submarine was only salvaged in a search for Nazi gold.

The red letters in the literary pavement leading to the library form a mysterious code.

A familiar otherworldly creature guards this 12th-century Scottish abbey.

There are plenty of wonderful panoramic vistas in Edinburgh, but not many are hidden smack in the middle of the Old Town.

At high tide this strange footbridge appears to have no purpose whatsoever.

An alley way dedicated to graffiti and street art is a constantly changing street gallery.

The massive machine creates cracking displays of indoor lightning.

This unique bridge curls up like a caterpillar to let boats pass and then unfurls again to span a small canal.

Besieged by war, this castle ruin has crumbled into a peaceful picnic spot.

Dating back almost 400 years, the oldest public collection library in the United Kingdom was once the study hall of Karl Marx.

The largest cave chamber in Britain—big enough to fit a whole cathedral inside.

Artists and musicians now rule over this former rail station.

Surreal riveted sea forts once protected the Kent shores from German attack.

The largest greenhouse in the world is home to over one million types of plants.

The longest hedge maze in the world.

Catacombs turned marketplace.

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

The "Kill Bill Church" was transformed into a place of worship after a long Hollywood history.

Salt is slowly eating away this abandoned saltworks town in the desert.

Etched into a dry lake bed, this massive directional indicator is accurate without magnets.

Abandoned anti-ballistic missile base.

America's only nuclear missile silo open to the public.