The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A museum dedicated to the alleged Roswell Incident.

A clear blue swimming hole with hidden caves, still unexplored.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

Within the former ghost town of Cisco is a carefully restored tiny town with one resident and its own art residency.

Thousands of years ago, Indigenous people painted images onto these canyon walls that are still on display today, provocative, mysterious, and enduring reminders of the people who lived here long ago.

The unusual patterns in this rock formation result from two distinct modes of weathering.

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

A 90-foot-tall psychedelic "tree" on the side of the highway has baffled passersby for decades.

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

This raised bulls-eye visible from space was the subject of an intense geologic controversy.

One of the world’s largest collections of petroglyphs records 2,000 years of human activity.

A striking, menacing sandstone peak towering above a landscape that's equal parts Mordor and the Moon.

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

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

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

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

Bizarre lunar-like landscape with thousands of large stone "hoodoos."

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

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

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

Around half a million years ago, these magnificent columnar basalt cliffs were formed from cooling lava.

This shallow pit was once used to send over 20,000 buffalo plummeting to their death.

Long before guestbooks and hotels, frontier travelers signed their names on this rock face.