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

These millipedes glow not out of attraction, but as a not-too-subtle warning.

A hidden subterranean installation offers a view of the sky.

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

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

San Francisco Bay's ghost town.

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

Abandoned bridge hidden deep in the San Gabriel Mountains.

An inconspicuous footbridge beloved by San Diego locals.

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

An unfortunate geological resemblance to Satan has labeled this Pasadena gorge as a passage to the underworld.

A meditative space out of a fantasy story.

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

The "world's biggest dinosaur" once housed a creationist museum in its abdomen.

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

A ghost town at the airport is now a refuge for blue butterflies.

The ghost town that ended up on Ebay.

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

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

Stripes of flowers bloom each spring in a 50 acre rainbow of color.

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

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

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

Carved by a waterfall in a hard-to-reach rock formation, this heart-shaped rock has inspired romantics for decades.