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

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

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

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

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

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

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

A collection of 20th-century automata, penny arcade games, and musical contraptions.

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

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

A pair of slides and a tree-lined stair corridor have been an urban oasis for nearly 40 years.

Finale of "William Tell Overture" can be heard as drivers pass over grooves in the road.

A castle that was built stone by stone by an eccentric journalist.

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

A museum befitting the city responsible for supplying the majority of the world's LSD.

A prohibition-style speakeasy takes up residence in the last Victorian residence in Hollywood.

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

Panorama exhibition hall in old silent theater with a beautiful backyard garden.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

Each year these high desert hills are absolutely covered with poppy flowers in a surreal show of nature.

This strange seaside tower got its name from a wealthy eccentric who would hide coins among its stones.

Get lost in this haunting fairytale art walk through a man-made eucalyptus grove.