The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

An architect's childhood fantasy treehouse made real.

Come for the speed, leave in love with the desert.

A 90-foot-tall psychedelic "tree" on the side of the highway has baffled passersby for decades.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

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.

When ecosystems collide in the arid Southwest.

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

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

The highest paved road in North America winds its way up Mount Blue Sky in Colorado to an altitude of 14,130 feet above sea level.

Inspired by a music box, a small town Vietnam vet carved an entire carousel full of animals by hand.

Population: 1.

The highest point in South Dakota contains the ashes of Valentine McGillycuudy, the "Holy White Man."

This replica stave church looks like a piece of Norway was simply plopped down in South Dakota.

A monument to the center of the North American continent may be off by a few miles.