The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A heavenly experience, right here on Terra Firma.

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

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

A lush green oasis in the middle of Chicago.

Odd outsider art installations surround a Gold Rush-era ghost town.

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

Take a drunken tour inside the world's largest known geode.

Towering basalt columns, a creation of fire and ice.

Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

A museum befitting the city responsible for supplying the majority of the world's LSD.

Where manatees are the snowbird vacationers in these balmy Florida springs.

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

The rocks in this arid basin leave trails of movement behind them.

The first declared National Monument in the United States.

At the "Garage Mahal" in Houston, car culture is about more than just driving.

Artist James Turrell's ode to dawn and dusk on the campus of Rice University.

A large instrument played by the wind.

A living time capsule of the 1960s Richardson Bay water-front.

At night, a grove of towering redwood trees growing through the pavement block out all light from the so-called “Dark Park” of Madrone Avenue.

One man's love of natural beauty led to the creation of this hidden granite monument.

Discover for yourself what Herb Caen referred to as "the best kept secret in the Bay Area."

This abandoned boat was left in place thanks to its rotting beauty.

Massive prehistoric mammals used these stones as oversized scratching posts.