Will Geer's outdoor theater started as a mountain retreat for actors, musicians, and other artists who were blacklisted during the Red Scare.

A vaudeville performer mounted this hollowed-out redwood log onto the chassis of a truck, and toured the country spreading a message of conservation.

This lonesome Monterey cypress has survived centuries of wind, salt, and at least one attempt at arson.

Colorful sedimentary rock layers provide opportunities both for hiking and photography.

Peek inside this sandy mailbox and you'll spot kids' letters to Santa.

This small shack near the entrance to Sequoia National Park has been in almost continuous operation for the last century.

A collection of anti-communist sculptures stands watch in the Mojave Desert.

At the western edge of Palm Springs, a rugged desert canyon trail leads to a waterfall at the base of the San Jacinto Mountains.

The first lookout in Yosemite.

A unique collection of old miners' cave homes carved in to the hillside cliffs near Death Valley.

Erroneously called the world's tallest flagpole, this landmark is devoted to "good neighborliness."

After the nearby mercury mine shut down, this town was abandoned and declared a Superfund site.

The only standing town in the United States that early Chinese Americans built for themselves.

Astronomers plan to launch a space telescope into orbit, to find out what exactly stands in the way of an asteroid hitting Earth.

Thousands of turbines whir at at the origin of North American wind power.

This unique formation appears as though an asteroid landed on the forest.

The second-largest giant sequoia in the world.

Deep vertical fissures like miniature slot canyons cut across the cemented volcanic rock of Black Point above Mono Lake.

In one of the hottest parts of the Mojave Desert, shallow bedrock forces the typically dry Mojave River to the surface in this canyon, providing a vital oasis for humans and wildlife.

The tallest bridge in California was constructed for a project that was eventually cancelled.

A unique museum where guests can rent and operate a locomotive.

A picturesque example of brute-force engineering conquering nature.

The oldest pictographs on this decorated rock formation in California's Carrizo Plain date back as many as 4,000 years.

Where the first "expert riders, willing to risk death daily" for the Pony Express were recruited.