One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

An architect's childhood fantasy treehouse made real.

The fifth-longest natural arch in the world, and the longest outside China.

Oddly shaped rock formation, misassociated with a nearby utopian community.

The world's largest military aircraft cemetery.

Limestone caves with spectacular showcase chambers.

A wild west cemetery in Tombstone, Arizona, provides a window into the Old West.

The world's largest rose bush has literally outgrown the pioneer museum it was planted behind.

An old saloon in the West filled with history, and according to some, a few dozen ghosts.

These aggressively sustainable art homes look like something out of 1970's science fiction.

A multi-storied adobe complex has been inhabited for more than a thousand years.

Legends surround this jagged rock formation in the New Mexico desert.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

A sprawling collection of over 106,000 toys from around the world.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

The oldest continuously occupied public building in the United States.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

Thousands of pieces of art have been carved into the rock at the site of an ancient volcanic eruption.

It's easy to see why this eclectic architectural wonder has been dubbed the "Spaceship House."

This immigrant bridge once spanned the Thames but is now a fixture of an Arizona city.

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.