Mysterious meeting place for UFO hunters near Area 51.

A unique museum where guests can rent and operate a locomotive.

The viewpoint for this attractive, off-the-beaten-path waterfall is reached by a paved, wheelchair-accessible trail.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

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.

Guns that have been defending San Francisco since 1904.

Concrete strongholds stand guard over the Golden Gate.

This abandoned boat was left in place thanks to its rotting beauty.

A raised boardwalk winds through a thicket of stunted, century-old trees no more than nine feet tall.

A trash dump made beautiful by nature's power.

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

This ultra-modern California span is actually a titanic solar clock in disguise built by famed architect Santiago Calatrava.

Hidden inside a gift shop that doubles as a museum, this gargantuan yo-yo can only be operated by crane.

Home of what was the largest hydraulic mine in the world, producing gold and the first diamonds in the U.S.