This mysterious petroglyph evokes the ancient swastika symbol but was later vandalized with the more troublesome Nazi one.

The beauty and the beast of hydraulic mining is on full display at this California Historic State Park.

A Cold War site complete with rusty structures, hiking trails, and beautiful views.

The world's first permanently occupied mountain-top observatory continues to report on the stars.

An abandoned 1920s-era stretch of cabins now overshadowed by the 66 Motel.

Massive prehistoric mammals used these stones as oversized scratching posts.

From the Difference Engine to the Cray-1, all under one roof.

Salt is slowly eating away this abandoned saltworks town in the desert.

Burping, gurgling geothermal mud pots by the Salton Sea.

Machinery left over from California's once thriving mercury industry now attracts artists and explorers.

Abandoned anti-ballistic missile base.

Huge otherworldly domed rocks on the shore of a deadly lake.

This desert oddity hides in plain sight thanks to a cartographic error and a desert explorer with a punny sense of humor.

One woman's Viking Castle on Lake Tahoe.

Abandoned Air Force base that has fallen into disrepair.

Secret US military film studio in the Hollywood Hills.

The overgrown ruins of a once thriving World War I-era copper mine.

No one's quite sure why there's a metal megaphone bolted on two rocks in the middle of the Mojave Desert.

The world's largest wooden trestle stretches across this desert canyon in Anza-Borrego Desert State Park.

Ancient human, animal, and geometric figures drawn in the earth.

This Pringle-shaped ledge makes for the perfect photo op.

This old mining town, deep in the California desert, has a year-round population of one.

The location of the last stand of Charles Manson's doomsday cult.

A world-class observatory in the California desert.