This concrete ship has had four careers - World War I tanker, floating amusement park, fishing pier, and artificial reef.

This crumbling warehouse was once the third-largest cannery in the U.S. and the first in the world to can green asparagus.

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

This 40-room dwelling tucked within a cliff was built by the basin's prehistoric residents.

This sinkhole in the Arizona desert is filled with carbonated, arsenic-rich water

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

This comprehensive collection features Native American artifacts dating back centuries.

A Wild West jailhouse that slid down the mountainside.

A spiritual vortex among the red rocks in Sedona.

A tunnel with windows, so you don't miss out on the impressive views.

The unusual patterns in this rock formation result from two distinct modes of weathering.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

A mining camp built around an unexpected occurrence of silver.

A new monument to an old grave that was uncovered during the rebuilding of a California ghost town.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

Napa's oldest building is now a Mexican restaurant.

The fossilized remains of ancient California redwoods.

A tribute to the life and work of the beloved "Peanuts" cartoonist.

Home to an apple tree that can produce 25 different varieties of fruit.

Ride on a fully-restored Nike nuclear-tipped missile elevator from the Cold War.

This lighthouse has been guiding shipping into the Golden Gate since before the American Civil War.

A working model of the entire San Francisco Bay and much of the Sacramento River Delta, complete with regular tides that change every 14 minutes.

The oldest U.S. Government building in California, and it's State Historic Landmark #1.

The first safe in this California town had to hold all the gold.