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

This old train trestle and collapsed tunnel once allowed the railroad to negotiate the steep slopes of the Colorado Rockies.

This interpretive path lets you get up close and personal with dinosaur bones.

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

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

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

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

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

This otherwise unremarkable ski town building marks the site of Butch Cassidy's first robbery.

The oldest operating cemetery in Denver is the eternal home of some of the Centennial State's most famous residents.

Hidden beyond a kitschy giant beetle is this remarkably sprawling collection of preserved insects.

The remains of the dam that unleashed a 15-foot wall of water on Denver.

The lost ruins of the forgotten ferry lie hidden beneath the silt.

Once a year, at exactly 11:11 a.m., this monument comes to life.

See massive fossils that are over 200 million years old in northeastern Arizona.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

A famous flea market artist's studio that's full of odds and ends.

Recycling meets art in this colorful barricade.

A wealth of pop culture statuary and green chile dishes give this roadside restaurant clout.

The winter home of thousands of beautiful snow geese and sandhill cranes.

In the middle of a desert subdivision, there is supposedly an impact crater site from Kcymaerxthaereal times.

Buried beneath the New Mexico sands are believed to be millions of copies of Atari's E.T. video game.

This pseudo-steampunk weapons facility is the world's largest wood and glue structure, and packs quite a wallop.

Wee (and not so wee) footprints that insects and reptiles of the Paleozoic Era left behind.