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.

The United States' first transcontinental automobile road came to its end at this spot in San Francisco's Lincoln Park.

This massive redwood tree has stood in Northern California for nearly 2,000 years.

This airfield played a key role in both World War II and the Cold War.

This small shack near the entrance to Sequoia National Park has been in almost continuous operation for the last century.

Where a railroad loops under or over itself to rise or drop more than 70 feet in a short distance.

A sparse, solitary sequoia still stands as a living tribute to the famous conservationist who planted it—but it's dying.

Centuries of crashing waves carved out this small hole in the rock, which lights up at certain parts of the year.

A porcelain company's former dumping ground, completely covered in pieces of collectible ceramics.

This cabin from the 1850s is one of the first structures built by Chinese immigrants in California.

Piled high inside this warehouse and coffee shop are salvaged goods that span every corner of the globe.

This little valley along Highway 1 is engulfed by thousands of lilies during the spring season.

One of the most elaborate displays of Jellyfish is on display at the aquarium.

It is locally loved and ridiculed for literally looking like poop.

A futuristic hovertrain is parked unceremoniously alongside a nondescript road.

Ruins battered by centuries of war and disaster offer a wondrous glimpse of medieval Ireland.

You can walk through the first Boeing Air Force One, which famously carried JFK's casket from Dallas back to D.C.

Robot jockeys ride their humped mounts to victory as part of a 21st-century twist on an ancient desert sport.

Quite simply the largest tree in the world (by volume).

An abandoned boat that's been stranded mysteriously for decades.

One of the largest-ever mental hospitals now sits abandoned, surrounded by 25,000 unmarked graves.

The bones of some 7,000 soldiers killed in the historic Battle of Solferino are stored here.

At this California chicken ranch, four bucks will get you 18 eggs and a chorus of dancing animatronic poultry.

A shining, cold, black organ lies in San Francisco's financial district.