Limestone caves with spectacular showcase chambers.

A spiritual vortex among the red rocks in Sedona.

An urban laboratory.

America's only nuclear missile silo open to the public.

A reproduction of earth's many biomes.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

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 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.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

This ghost town was once a cult-like religious utopian settlement.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

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

Even in death, he's still your huckleberry.

A house carved into a rock in the 1940s.

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

It would be easy to walk past this unusual piece of art and have no idea it pays tribute to the odd life of a real chicken.

The spot in the Mile-High City that's exactly 5,280 feet above sea level (at least for now).

A small horde of mythical creatures lurk almost imperceptibly within the museum's wildlife dioramas.