Colorado's only active volcano last erupted around 4,000 years ago.

A little-known hot spring haven right below the highway.

This Rocky Mountain mansion was the luxurious home of the authoritarian leader of a company town.

The site of a defunct mill, that once supplied marble for the construction of the Lincoln Memorial.

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

This distinctive snowfield on the slopes of a Colorado fourteener has several legendary origin stories.

A fake mine that was made using real mining techniques which is also used as a community center.

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

These towering cliffs crystalize each winter, forming sheer walls of ice that are open for climbing.

A multicolored mineral mound dribbles piping hot spring water right off the side of a highway.

A hotel with a rich Wild West history of miners and bootleggers.

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

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

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

Ute tour guides have been sharing the ancient dwellings and rock art inside this large park with visitors for more than 40 years.

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

Stay in a luxury cabin or refurbished Airstream in this former mining camp-turned-retreat.

The decaying ruins of a failed mining company’s water diversion project cling to the side of a desert canyon.

A river runs through this remote valley in a very unexpected way.

A unique arch graces the Dolores River Canyon near the Hanging Flume.

A remote sandstone plateau named for a legendary cattle rustler.

Two creeks flow out of either end of this canyon in opposite directions.

For over a century, it has been a tradition to raise a flag at the top of this 450-foot sandstone pillar on the 4th of July.

This remote Colorado canyon is home to the second-largest collection of natural arches in the world.