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

Abortion, prohibition, religion, war, and fear all play a part in the history of this idiosyncratic Pacifica castle.

A large instrument played by the wind.

Another of California's unused Cold War missile defense complexes has become a graffiti gallery.

This controversial depiction of the "Founder of California" looks as though it was sculpted from mashed potatoes.

A burnt orange monolithic dome structure perched on a hillside near Interstate 280.

The old Niles Canyon Aqueduct in the San Francisco Bay Area is a bemusing and secret trail through nature for wayward travelers.

An archive of nearly every day of Buckminster Fuller's life.

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

A giant can of fruit cocktail is all that remains of what was once the world's largest cannery.

A statue commemorate Tommie Smith and John Carlos's brave protest at the 1968 Olympics, a watershed moment for civil rights.

Elephant seals and sea lions have turned the abandoned buildings on this island into their endangered love shack.

Every year, over 25,000 monarchs overwinter in Pacific Grove.

Massive prehistoric mammals used these stones as oversized scratching posts.

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

This collection of hand fans doubles as a history of femininity.

California's own majestic geyser is powered by a subterranean volcano.

A tribute to the life and work of the beloved "Peanuts" cartoonist.

The official atomic museum of the United States explores the explosive and productive history of a much maligned energy source.

A "gravitational anomaly" located in the redwood forests just outside of Santa Cruz, California.

A bronze monument to the infamous radio broadcast in the real New Jersey town where the fictional Martians crash-landed.

An unrealized dream to wirelessly electrify the entire Earth.

This beautifully deceptive waterfall is something far different from what it appears to be.

High on a hill overlooking Los Angeles lives a world famous, high power conical Tesla Coil.