The largest self-built castle in the U.S., six decades in the making.

The highest bridge in America was built for an almost unnervingly small amount of money.

Silver in the hills led to the speedy creation of this boom town and a lack of it saw the town abandoned nearly as quickly.

Hidden beyond a kitschy giant beetle is this remarkably sprawling collection of preserved insects.

While most of the games in this arcade take quarters, that would have been a small fortune when they were made.

At one time this small mining village was the highest town in America but now it sits abandoned while the mine churns on.

Air Force Academy Chapel made of 100 identical tetrahedrons works to inspire those of all religions.

This hot dog-shaped diner has moved all around Colorado, never been to New York.

Paranormal experiences in this hotel's room 217 led Stephen King to write "The Shining."

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

Every year, over 25,000 monarchs overwinter in Pacific Grove.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

A burnt orange monolithic dome structure perched on a hillside near Interstate 280.

Rodin's famous depiction of Dante's 'Inferno', amidst a sculpture garden of many of his other works.

This concrete tangle of square pipes has stood as a proud thorn in the city's side since the '70s.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

San Francisco's newly reopened hands-on science museum.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

Depicting scenes of everyday life - and specific individuals - in Great Depression era San Francisco.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

You might know it as the Overlook Hotel, but the inside is not going to be familiar.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.