The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

At the base of the Golden Gate Bridge, a small sign basically begs for a high-five.

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

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

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.

Once the largest windmill outside of Holland, with enormous 114 foot sails.

Guns that have been defending San Francisco since 1904.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

A garden oasis filled with flowers mentioned in the works of William Shakespeare.

This knobby, drooping New Orleans oak is a favorite place both for climbing and for meeting giraffes.