The largest source of fossilized insects anywhere.

Climb to the top of this spiritual tower, and you'll be rewarded with spectacular views.

Unlike most arches, this geological oddity formed in a volcanic dike.

This deserted Gold Rush town is home to a Masonic lodge that, strangely enough, still holds meetings.

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

This hot dog-shaped diner has moved all around Colorado, never been to New York.

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

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

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

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

The site where a nuclear bomb was lowered over 8,000 feet underground and detonated as an experiment in natural gas extraction.

A coal fire has been burning underground here since 1896.