Concrete strongholds stand guard over the Golden Gate.

This abandoned boat was left in place thanks to its rotting beauty.

An enchanting tunnel of cypress trees leads to an old morse code station still used today.

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

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

A huge musical instrument played by the ocean.

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

The remains of a ruined mansion memorialize the 1906 earthquake.

A monumental cross hides in the trees in Golden Gate Park.

Thirteen trees representing the original thirteen colonies were planted with soil from historic Revolutionary battlefields.

A hidden subterranean installation offers a view of the sky.

An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

San Francisco's first World's Fair, dedicated to the wonders of California.

A masterpiece in Golden Gate Park by virtue of the artist’s debt.

The legendary statue-hating superintendent of Golden Gate Park is honored with... a statue.

A favorite haunt of dinosaur loving children and hallucinogen loving hippies alike.

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

The graffiti-covered remnants of a former triangulation station are balanced precariously on this California peak.

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

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

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

Here, visitors can swing with the waves of the Pacific Ocean.

A strange house built only at night, with rumored mystic inspiration.

This odd California folly seems like it was almost designed to accumulate urban legends.