When zealous marijuana enthusiasts kept stealing the "Mile 420" highway marker, the State of Colorado got creative.

This fully restored synagogue explores the American Jewish experience along the old frontier.

A beautiful combination of living flora with preserved bones covers the shelves of this shop.

This nearly abandoned town was once a thriving mining community until a series of fires.

This National Natural Landmark is one of the best examples of a “mass wasting” in the world.

The remnants of the base where US Army troops learned how to fight in extreme conditions.

This 19th-century ranch is being transformed into a residential library with thousands of books about the natural world.

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

Historic, 19th-century wagon wheel ruts cut into soft volcanic ash.

Paleoamericans built these ancient walls high in the Colorado Rockies as part of an extensive hunting system.

The giant stump of the once towering cottonwood where Ute people held tribal meetings.

Happen to come across a dead eagle? Send it to America's official dead eagle warehouse.

This now-abandoned outcrop is an important Native American spiritual site, overtaken by European settlers and mining pollution.

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

This three-mile concrete levee in Pueblo, Colorado was transformed into the world’s longest painting.

Open-air cremations in Colorado's self-proclaimed spiritual mecca.

Birds with backpacks expedite film development for a rafting company on a remote Colorado river.

Hidden high on a remote mountain peak is a humbling and mysterious Vietnam War memorial.

A prehistoric rock shelter that's literally in someone's backyard.

A seven-story 1920s mausoleum outside Denver houses thousands of remains.

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

The site of the "Bone Wars" between two rival paleontologists during the dinosaur rush of the 19th century.

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

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