A hidden network of subterranean passageways lies tangled beneath Indianapolis' bustling City Market.

This natural wonder drops 16 stories straight down through rare flora and streaming waterfalls.

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

This naturally-sourced hot spring is now home to a clothing-optional resort.

This frequently-photographed waterfall takes only a short hike to visit.

Hollowed out cedar log tubs set in an ancient towering forest.

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

A one-of-a-kind collection of a unique medium.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

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

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

A bizarre house filled with an astounding array of collections.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

These picturesque Hawaiian falls are home to a rare species of fish that uses a special sucker to climb up cliffs.

This WWII plane died a quiet death, and is now a garden eel playground.

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

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.