Adolph Sutro's little-known, geographically inaccurate, deprecated monument.

One of Mexico's least-visited archaeological sites is tucked away inside a theme park.

Amsterdam's Red Light District leaves little to the imagination.

Downieville's largest Gold Rush structure still standing has one of the longest bars in California.

A fire lookout atop a glacial pinnacle is reached by climbing three vertiginous flights of stairs.

The beauty and the beast of hydraulic mining is on full display at this California Historic State Park.

California's oldest existing theater building hosted an impressive cast of celebrities, including hosting Mark Twain's first lecture.

This fully intact Neoclassical-Greek Revival style firehouse operated until 1938.

Hidden in a hotel parking lot is a strange historical plaque erected by an obscure fraternal society.

The Empire Mine is "one of the oldest, largest, deepest, longest and richest gold mines in California."

The tallest bridge in California was constructed for a project that was eventually cancelled.

The interior of the Overlook Hotel in "The Shining" was based on this Yosemite original.

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

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

A volcanic cone that formed over 600 years ago.

Towering basalt columns, a creation of fire and ice.

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

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

Explore more than 130,000 new and used books in the "world's largest outdoor bookstore."

Hidden in the Santa Ynez Mountains off Highway 154, this tiny restaurant once served as a stagecoach stop.

California's largest steel arch bridge.

The ruins of the castle that chemicals built.

Get up close to emus and ostriches, or buy their tasty meat.

A Mysterious Masonic tomb in San Luis Obispo.