Costumed elves and mountain bikers co-exist peacefully at this abandoned Christmas-themed adventure park.

One of the ghostly stops along Route 66.

The "Fun Spot of the Desert" is now a haunting ruin, and a reminder that putting a water park in a desert is a bad idea.

The site of murders and Satanic cult gatherings.

The remains of a ruined mansion memorialize the 1906 earthquake.

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.

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

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.

The ghost town that ended up on Ebay.

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

The now-abandoned tunnels were built for the transcontinental railroad on the route where the first wagon train entered California.

Experience a quartz crystal sound bath inside a storied, all-wood sound-chamber.

This grand mansion has starred in everything from Bones to Buffy.

Visible below the waves are memorials to the city's Gold Rush dead.

An outdoor sculpture park of giant pink robots and post-apocalyptic Christmas scenes.

Explore 10 acres of environmental sculptures.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

This Big Sur waterfall drops 80 feet directly into the Pacific Ocean, and inspired the hillside house up top.

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

A shop full of natural curiosities, carnivorous plants, and costumed taxidermied mice.

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

Canyon walls shrouded in ferns.

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