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

An invitation-only museum of items natural and bizarre, arcane and exotic.

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

The final resting place of a space program monolith.

The largest drain hole in the world.

Eons old volcanic activity created one of the most stunning rock formations in the United States.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

Abandoned bridge hidden deep in the San Gabriel Mountains.

A Swedenborgian glass church surrounded by redwoods sits perched atop a massive landslide area.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

Behind this beachfront shop lies a spectacular, colorful sea cave with an equally colorful past.

Carved by a waterfall in a hard-to-reach rock formation, this heart-shaped rock has inspired romantics for decades.

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

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

A trash dump made beautiful by nature's power.

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

The rocks in this arid basin leave trails of movement behind them.

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

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

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

A hand-built folk art installation covered with messages of God's love.