When ecosystems collide in the arid Southwest.

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

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

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

A beautiful geyser under environmental threat.

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.

This concert pavilion on the shore of the Great Salt Lake has been destroyed by fire, water, and disinterest but keeps coming back.

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

Once a menacing challenge for trailblazers, this trail is now the most scenic drive in Utah.

Bizarre lunar-like landscape with thousands of large stone "hoodoos."

This raised bulls-eye visible from space was the subject of an intense geologic controversy.

Few things look more out of place than the electric blue ponds in the reddish-brown desert of Utah.

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

One of the world’s largest collections of petroglyphs records 2,000 years of human activity.

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

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

Dramatic river bend surrounds a natural red-rocked pedestal.

See massive fossils that are over 200 million years old in northeastern Arizona.

The largest natural travertine bridge in the world is nestled in a small canyon in central Arizona.

The capitol city's oldest existing cemetery.

The oldest orange tree in California spawned a generation of citrus farmers.

These cinderblock farmhouses were actually World War II radar stations in disguise.

A natural dome made of volcanic glass in Inyo National Forest.