This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

Rippling sand dunes frozen in the Arizona rock.

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

This hidden art nouveau gem was designed by an architect in search of a national style.

This cave holds a surprisingly colorful variety of geological oddities.

California's own majestic geyser is powered by a subterranean volcano.

The artist James Turrell is repurposing an extinct volcano crater as an observatory to experience the cosmos.

An impressive collection of over 50,000 minerals including moon rock from the Apollo 17 mission.

If you want to take a peek at Area 51, this is legally as close as you're going to get.

This crumbling stump is all that remains of what was once thought to be the oldest living organism.

This central Nevada cave is the spiritual home of ancient and enigmatic pictographs.

These huge stone ovens in the desert fueled the Nevada silver boom, and may have also been a hideout for outlaws.

Only intact Ichthyosaur skeleton in the United States.

A gothic palace of endless stalagmites and pseudoscorpions waits within one of the world's most beautiful caves.

The longest living non-clonal organisms on Earth.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

Where NASA's satellites and rovers phone home.

This dormant volcanic crater has been converted from a roiling pit of magma to a pleasant hiking spot.

NASA's leading space science lab started by a co-founder with deep ties to the occult.

Inspiring Earthlings to Boldly Go.

This former stomping grounds of the most eminent astronomers of the early 20th century.

Suburban observatory was personal lab of the father of modern astrophysics.