Radioactivity still cause for concern at this urban explorer's paradise.

A rough granite monument marks the spot where Europeans first caught sight of the San Francisco Bay.

A 1920s speakeasy that had rum runners racing up and down the shores of California.

From the sky, a kaleidoscope of color brightens the grey landscape of the San Francisco Bay.

San Francisco Bay's ghost town.

One of the largest free-standing structures ever built, this dirigible hangar is now simply a giant skeleton.

The world's first permanently occupied mountain-top observatory continues to report on the stars.

Once close to extinction, there is no shortage of elephant seals on the beaches of Año Nuevo State Park.

Haunting and beautiful trees, doomed to die.

The stately birthplace of California's statehood.

This remarkably simple jail went over a century without an escape.

A tree grown from astronaut seeds which were exposed to cosmic rays.

An old whaling station now serves to give the public a look at the commercial whaling industry, no longer a part of Monterey's economy.

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

The oldest continuously operating church in California.

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

This municipal playground was co-created by the father of one of the most playful characters ever.

The lush coastal city of Astoria is riddled with forgotten secret sidewalks.

This graveyard is the eternal home of many brave pioneers who settled the Great Northwest.

100-year-old shipwreck you can walk up to at low tide.

Where Nor'easters go to die.

Only known mainland rookery of the threatened Stellar sea lion.

Contractors in this Oregon town have been stamping their names in sidewalks since 1908.

The wooden airship was the largest flying boat ever built.