This once-popular otherworldly landscape was formed by one of the largest volcanic eruptions in history.

In the middle of a suburban Denver neighborhood is a cave that once provided solace for a prominent Ute chief and his family.

These decaying bridges 1,000 feet high are a reminder of the skill it took to cross the Colorado Rockies by rail.

One of the largest Buddhist stupas in North America is built of concrete designed to last 1,000 years.

While most of the games in this arcade take quarters, that would have been a small fortune when they were made.

At the tallest peak in Colorado, an electrifying mix of thin air, lightning, and rivalry.

Colorado's only true geyser is hidden within the San Juan National Forest.

An architect in Aspen used psychedelics as his muse while building this mushroom masterpiece.

Despite being one of the most photographed vistas in the Rockies these twin peaks are rightfully known as the "Deadly Bells."

This spectacular track has run continuously since 1882.

The superstar of Cold War nuclear bunkers has been featured in countless films but is now barely operational.

When ecosystems collide in the arid Southwest.

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

This naturally-sourced hot spring is now home to a clothing-optional resort.

A breathtaking array of ancient Pueblo structures and artifacts counterintuitively preserved by neglect.

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

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

Wondrous sandstone hoodoos where Native Americans collected clay for pottery, 9,000 years ago.

This 100-foot tall bluff located in the western plains of Kansas overlooks a massive reservoir.

These otherworldly limestone formations jut out from the Kansas prairie.

Journey up the capitol building's cupola for an amazing view of Topeka.

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

It's big, it's a ball, and it's made of twine—the world's largest of its kind.

The United States's largest hand-dug well is topped with a state-of-the-art museum.