A mesmerizing disco ball-like sculpture along the Sacramento River Walk.

Puzzling...this tree looks like an assemblage of dismembered monkey limbs.

The capitol city's oldest existing cemetery.

The California capital city once stood 10 feet lower than it does today.

Where America's first doomsday cult awaited the end of the world.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

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

This private residence was the template for one of the most beloved television homes of all time.

A 300-ship graveyard, with a few still visible at low tide.

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

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

The only theatre in the world constructed specifically for sound movement.

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

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

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

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

A huge musical instrument played by the ocean.

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

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