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

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

One of the world's largest collections of pathological specimens.

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

A little slice of Japan and its aesthetics in London's Holland Park.

A kaleidoscopic warehouse-maze of handmade neon signs.

It's a mystery how these curious columns wound up in an Edinburgh suburb.

This enormous, elaborate tomb looks oddly out of place next to a suburban Edinburgh bowling club.

The names Lúthien and Beren can be found inscribed on the shared grave of the famous writer and his beloved wife and muse.

The mysterious megaliths have enchanted and intrigued visitors for thousands of years.

A strange rock with a sinister reputation lurks within the crimson waters of this Scottish glen.

This 1920s Dutch barge is now a floating bookstore.

The sign at the garden gate reads: "These Plants Can Kill."

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

These fantastically named natural pools look like something out of a Scottish myth.

Legends say this red sandstone monolith and the dozens of smaller boulders that surround it were once a coven of witches—before a Scottish wizard turned them all to stone.

Amsterdam's Red Light District leaves little to the imagination.

This museum inside Amsterdam's largest cemetery explores how people deal with death.

Preserving the research tools, unexpected inventions, and odd collections of generations of college professors.

The half-finished remains of what would have been Scotland’s biggest piece of landscape art.

The recurring nature of this geographic feature might make it unique in the world.

A re-purposed wooden sculpture, depicting one of Scotland's most beloved writer's amphibious creations.

This ancient holy well is older than much of the city that surrounds it.

It's said this was once the home of King James V's pet lion.