San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

San Francisco Bay's ghost town.

The unbelievably opulent home built for an infamous newspaperman.

The oldest burial ground in the city, final resting place of city founders, Ohlone natives and murderers alike.

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

A storybook European village in Berkeley.

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

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

One of the ghostly stops along Route 66.

An extraordinarily ornate museum in San Diego holds wondrous anthropological treasures.

Travelers exchange letters with woodland creatures at this mini post office.

This naturally heated mountainous creek has created a group of neon blue pools of potentially deadly boiling water.

This massive redwood tree has a hole in the base big enough to drive through.

The remains of a ruined mansion memorialize the 1906 earthquake.

This rare example of a "tidefall" is a spectacular drop from the cliffs down onto the beach.

The final resting place of a space program monolith, soon to be unveiled again to the public.

The largest drain hole in the world.

The largest permanent Monopoly board makes one of the longest games even bigger.

Once thought to be the oldest living tree in the world, Methuselah was germinated before the Egyptian pyramids were built.

The ghost town that ended up on Ebay.

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

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

Big gun installations, built over a massive cemetery, now abandoned & hidden in trees.

An inconspicuous footbridge beloved by San Diego locals.