An artsy hidden staircase leads to breathtaking views of San Francisco.

Sprawled across the Great Hall ceiling are various constellations and images relating to the zodiac.

Old-fashioned knowledge and modern engineering create the world's only rotating boatlift.

The mystery of this small, brick pond eluded its possibly only investigator until his death.

This cramped crevasse saw the entire population of its island suffocated inside its depths.

This ethereal, rainforest-like gorge is home to waterfalls, quaint bridges, and fairy folk.

This Scottish bridge seems to compel dogs to leap to their death.

A beautiful Greco-Roman structure houses a well once believed to have healing powers.

Climb this overlooked gem's spiral staircase and you'll be rewarded with spectacular views of Glasgow.

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

The elaborate clockwork contraptions in this Scottish gallery create small worlds of whimsy and horror.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

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

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

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

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

360° views of the city plus five floors of optical illusions and hands-on science.

A 30-acre garden inspired by the principles of modern physics.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

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

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

This mesmerizing and surreal landscape features intricate patterns of white and red sandstone.

A stretch of highway even lonelier than the so-called "Loneliest Road in America."

Located in the world's highest-altitude Dark Sky Community, this observatory welcomes amateur and professional astronomers alike.