The Citrus Variety Collection at UC Riverside contains two trees of each of the 1,000+ varieties of citrus.

This concrete ship has had four careers - World War I tanker, floating amusement park, fishing pier, and artificial reef.

A remote desert lookout offers unparalleled views of the California badlands for those who brave the trek.

A huge collection of rocks, gems, and crystals.

An abandoned boat that's been stranded mysteriously for decades.

A massive volcanic plug is now a protected area that hosts a number of bird species.

A New England-style lighthouse along California's beautiful Highway 1 gets a re-do.

Once the largest winery in the world, this castle-like building now sits abandoned on the San Pablo/San Francisco Bay shore.

A massive hydrovolcanic explosion left a half-mile wide crater in Death Valley.

An expansive and intricately restored mansion remains from over a century ago--and so do its ghosts.

The sea once considered an ecological wasteland is now called "crown jewel of avian biodiversity" by scientists.

At this deceptively beautiful beach, nothing is what it seems.

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

The oldest lighthouse on America's west coast no longer needs keepers, yet they maintain the site anyhow.

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

Suburban observatory was personal lab of the father of modern astrophysics.

A pier that used to act as a busy ferry dock is now a decaying favorite of local fisherman and urban artists.

A herd of 150 bison live on California's Santa Catalina Island and are at the heart of an ongoing debate between environmental protection and economic expansion.

A stranded woman lived alone on this remote island for 18 years, inspiring the great children's novel "Island of the Blue Dolphins."

Centuries of crashing waves carved out this small hole in the rock, which lights up at certain parts of the year.

A mountain range on an active U.S. Navy base hides thousands of mysterious prehistoric rock carvings.

The sole surviving relic of the San Francisco neighborhood cobbled together from old horsecars and streetcars.

This historic tower in the California desert promises visitors a "vortex of good vibes".

Each winter this underground cave forms a dazzling ice palace.