A popular swimming hole that hides one of America's most deadly diving spots.

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

What is the Thing?

Miniature art that tells an enormous story.

Some of the tallest ancient American ruins continue to inspire awe and curiosity.

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.

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

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

See massive fossils that are over 200 million years old in northeastern Arizona.

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

A sharp bend in a dramatic river canyon cut through red rocks.

Most-visited and most-photographed slot canyon in the American Southwest.

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

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

The largest island on the great salt lake is home to curious creatures and strange stories.

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

Come for the speed, leave in love with the desert.

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

A museum devoted entirely to the rattlesnakes and snake-related art.

This quirky hot springs town known to locals as "T or C" was named after a radio show.

A small metropolis of Pueblo cave dwellings have been carved right into the hillside of this national monument.

These ruins of a pre-Columbian cliff village are among the most beautiful and well preserved in New Mexico.

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