The last physical evidence of the Lewis and Clark trail is one of their autographs etched into this giant rock.

The world's largest mineral hot springs is home to a herd of bison, a free public bath house, beautiful mineral formations, and a terrifying swinging bridge.

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

At the time of its completion, it was the tallest dam in the world.

A beautiful geyser under environmental threat.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

An architect's childhood fantasy treehouse made real.

This rustic old building is said to be the most photographed barn in America.

Inside this striking glass building, visitors can see thousands of dinosaur fossils in the positions that nature deposited them more than 150 million years ago.

The location where the iconic movie character declared it was time to go home.

This balancing rock is one of Utah's most unusual geological formations.

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

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

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

Strange red rock formations that have been attributed to a higher power for hundreds of years.

A short but powerful waterfall resides amid Colorado’s Great Sand Dunes.

A picturesque (all-natural!) beach in a landlocked state.

When ecosystems collide in the arid Southwest.

A small horde of mythical creatures lurk almost imperceptibly within the museum's wildlife dioramas.

A focal point of in Denver’s skyline for over a century, inspired by a Venetian basilica.

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

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.