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

Since 1973, this block has been home to the most concentrated collection of murals in San Francisco.

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

This municipal playground was co-created by the father of one of the most playful characters ever.

Haunting and beautiful trees, doomed to die.

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

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

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

'Cause the fence start shaking, the earth was quaking.

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 mysterious round rocks of Schooner Gulch.

This whimsical seashell-shaped place of worship was designed to blend into its surroundings.

This historic California cemetery holds the bodies of veterans of both the Civil War and the Donner Party.

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

California's own medieval Italian castle, authentic down to the 300-year-old iron maiden in the dungeon.

The former Naval shipyard is open for exploring - mostly.

Depicting scenes of everyday life - and specific individuals - in Great Depression era San Francisco.

A miniature view of the park, caught in time.

A winding path built in secret on the edge of the continent.

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

Once the largest windmill outside of Holland, with enormous 114 foot sails.