Floating man-made island and upscale restaurant.

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

A popular tourist cave with a dark past.

The haunting ruins of Jack London's dream house.

A world-class observatory in the California desert.

Playable, historic pinball machines fill this Alameda museum.

A playground built by the kids that is a child's wonderland, and a helicopter parent's nightmare.

The fossilized remains of ancient California redwoods.

"Only the devil could play golf here."

An "anarchical" no man's land, complete with garbage sculptures and a hobo-run "Landfillian Library."

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

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

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

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

One of the ghostly stops along Route 66.

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

Nestled in the heart of San Francisco’s bustling Financial District stands a unique homage to the Mayan and Beaux Arts.

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

One of the most unusual geological features, recognizable from a dozen hit movies.

Most famous work of one of Frank Lloyd Wright's sons.

This impressive tunnel was dug entirely by hand over the course of 36 years.

The most unique castle in all of Southern California, entirely constructed from repurposed materials.

Small museum packed with artifacts recovered by the man rumored to be the real-life inspiration for Indiana Jones.

Home to the "Circus" trees created by Axel Erlandson.