The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

Steep canyon walls hide a forested oasis in the West Texas desert.

This sacred cavern, 400 feet deep, is home to millions of bats and an ancient burial ground.

A Texas cave network is home to some of the world's most spectacular-looking and bizarrely named mineral formations.

The Grand Canyon of Texas.

An emerald-green grotto just a short trip from Austin.

These Pre-Columbian petroglyphs contain representations of birds, deer, hunters, and even some early Native flute players.

These otherworldly limestone formations jut out from the Kansas prairie.

This 41,000-acre wetland complex is the largest marsh in the interior of the United States.

Curious rock formations in a tiny Kansas state park.

A landscape of massive spherical boulders are the main attraction in this Kansas State Park.

One of the Eight Wonders of Kansas and the first official National Natural Monument these stark formations look like nature's Stonehenge.

Roaming bison and a spectacular view at the highest point in Nebraska.

Other-worldly rock formations and ancient fossils abound in this unique stretch of Nebraska badlands.

This erect, phallic geological spire wasn't always named so domestically.

This cave was hidden for thousands of years, storing the worldly goods of ancient Native Americans.

One of the most remote spots in America and the first protected wilderness area in Nevada, named after an old legend.

Water of undetermined depth has attracted rare fish and cult leaders alike.

Thousands of glyphs created by an unknown culture decorate the rock formations of this canyon.

This dry lake bed contains the oldest known petroglyphs in North America.

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

Nearly 300,000 acres of wildlife, natural splendor, and a hidden ghost town have been designated a national monument.

The largest man-made crater in the U.S. marks the spot where we once tested mining with nukes.

Singing sand that stands as the final remains of an ancient lake.