In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

This isolated outpost was once the only place to cross the Colorado River for hundreds of miles.

These mid-century motels once housed the workers who built the Glen Canyon Dam.

Dramatic river bend surrounds a natural red-rocked pedestal.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

A monument to the one-armed geologist who led the first documented expeditions through the Grand Canyon.

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 remnants of a creative early method of wildfire prevention.

Legends surround this jagged rock formation in the New Mexico desert.

This small interfaith chapel lies not far from the rim of the Grand Canyon.

Home of the International Space Hall of Fame.

If drivers cross the rumble strip on this stretch of Route 66 at just the right speed it plays "America the Beautiful."

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

An homage to everyone's favorite prehistoric cartoon family.

The eroded core of an ancient volcano is now accessible by a short hike.

A wealth of pop culture statuary and green chile dishes give this roadside restaurant clout.

This historic national park is covered in the stunning ruins of red rock pueblos.

A one-of-a-kind sundial at the Very Large Array honors a radio astronomy pioneer, incorporating the original piers from his breakthrough radio telescope.

Twenty-seven massive radio antennas on the high plains of New Mexico search for life on other planets.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

Ancient pueblos built into the base of a natural canyon wall.

A Wild West jailhouse that slid down the mountainside.