It should come as no surprise that the best view of the Hollywood sign is from Batman's lair.

A 140-year-old castle with underground caves hidden in San Francisco.

Towering basalt columns, a creation of fire and ice.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

An underground mansion with fruit-bearing trees and grapes growing beneath the surface of central California.

A trash dump made beautiful by nature's power.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

A huge musical instrument played by the ocean.

The largest drain hole in the world.

The haunting ruins of Jack London's dream house.

The former Naval shipyard is open for exploring - mostly.

This infamous prison has a store where you can buy goods crafted by incarcerated people.

A working model of the entire San Francisco Bay and much of the Sacramento River Delta, complete with regular tides that change every 14 minutes.

Once close to extinction, there is no shortage of elephant seals on the beaches of Año Nuevo State Park.

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

Successful artist residence program has filled this ranch with dozens of sculptures over the years.

Subterranean house made out of a grain silo, located in the Santa Cruz Mountains.

An ominous concrete cube cuts a dystopian silhouette atop this California mountain.

A humble garage, world-famous for being the epicenter of a technology revolution.

Apple memorabilia in an undisclosed warehouse, hidden for undisclosed reasons.

A pair of pure white felines guard the entrance to a spot of California real estate established as an artist's haven.

A life-sized mammoth sculpture marks the spot where the remains of a Columbian mammoth were discovered in 2005.

A giant chess set, minus the psychedelic drug trip.