A speck of nature and art in one of San Francisco’s most notorious neighborhoods.

This little blue house pokes out over the campus of UC San Diego, seven stories high.

Early prototype for Frank Lloyd Wright's Guggenheim.

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

This impressive tunnel was dug entirely by hand over the course of 36 years.

A popular tourist cave with a dark past.

The remains of a 12th-century chapter house in Golden Gate Park.

The abandoned train depot now doubles as a well-placed rest stop for those who take the road less traveled.

A house built from trash known as the poor man's Hearst Castle.

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

Built by the inventor of the radio, this abandoned hotel has housed early radio employees, military men, and a dangerous cult.

The interior of the Overlook Hotel in "The Shining" was based on this Yosemite original.

The lighthouse central to the 1980s horror classic "The Fog" is, in fact, located in one of the foggiest areas of the Pacific Coast.

Neither Spanish settlers nor anyone since has been able to tell who built these strange California rock walls.

The fossilized remains of ancient California redwoods.

One of the most unusual geological features, recognizable from a dozen hit movies.

Named after a bandit and the star of several Hollywood prehistoric landscapes, these sandstone formations are a historical part of the Los Angeles natural landscape.

Half of a house.

Sunset-colored dunes of volcanic ash make taking a poor photo impossible.

One of the oldest reform schools in the United States, home to wayward boys such as Merle Haggard, now abandoned.

Gold Rush-era tombstones line the park's paths.

This print shop boasts one of the largest pinball arcades in San Francisco.

This “living museum” at UCLA exhibits thousands of plant species from all over the world.

An overlooked and unassuming engineering marvel.