The world's largest sticker ball weighs in at a mighty 231 pounds.

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

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

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

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

This spectacular track has run continuously since 1882.

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

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

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.

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

This museum glorifies the humble potato.

Natural rock water slides hidden in the remote forests of northern Idaho.

A semi-scholarly approach to sex.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

Collapsing castle on the Hudson river was once the storage site of military surplus business.

Waterway populated with abandoned projects, including a submarine.

The famous author's cottage hideaway.

One of only two commuter aerial tramways in the United States.

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

A ruined mansion hidden in the woods of the Hudson Valley, home of a tragically doomed romance.

From scholastic to sepulchral - now under reconstruction.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.