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

An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

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

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

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.

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

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.

Its buzzing collection honors vibrator history.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

An artsy hidden staircase leads to breathtaking views of San Francisco.

An ominous concrete cube cuts a dystopian silhouette atop this California mountain.

A burnt orange monolithic dome structure perched on a hillside near Interstate 280.

Eight huge lanterns lining a city street can change color on command.

It took years to decode its mysterious messages.

At night, this glittering musical tunnel draws skaters and photographers.

This 252 step staircase offers stunning views of San Jose.

A mysterious monument covered in a binary code marks the heart of tech.

Anyone can control this glittery light installation with just a phone call.

A giant chess set, minus the psychedelic drug trip.

A statue commemorate Tommie Smith and John Carlos's brave protest at the 1968 Olympics, a watershed moment for civil rights.

The largest permanent Monopoly board makes one of the longest games even bigger.

An extensive collection of ancient Egyptian artifacts and mummies.