Curious cave that stays a cool 56 degrees all year long.

Less a museum than a bizarre fantasy world created by artists and engineers.

European castle ruins in an American state park are actually the product of death and grief.

Narrow slot canyons in a badland eroded into soft sedimentary rock provide an otherworldly landscape in this remote Nevada state park.

Twelve plaster figures inspired by da Vinci's famed painting haunt the desert landscape above a real-life ghost town.

The drama of nature in full effect in this Nevada State Park.

Dyed by iron oxide over centuries, these sandstone rocks rise thousands of feet into the sky.

Odd outsider art installations surround a Gold Rush-era ghost town.

Contains a wealth of information about the first exploration and later use of the Green and Colorado Rivers.

A spectacular overlook of the Little Grand Canyon of the San Rafael River, a deep sandstone gorge streaked with orange, red and white in a remote, uncrowded part of Utah.

At this gas station in the middle of the desert, a convenience store has been carved directly into the rock.

The unusual patterns in this rock formation result from two distinct modes of weathering.

Erosion and various mineral deposits give this striking canyon its distinct color and soft appearance.

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 quiet park's strange sedimentary spires were named after Kodak's color film.

A tunnel with windows, so you don't miss out on the impressive views.

Despite its name, this route in southern Utah offers a heavenly day trip.

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

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

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

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

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

A short but powerful waterfall resides amid Colorado’s Great Sand Dunes.