The exit of the largest prisoner-of-war escape attempt on American soil during World War II.

An abandoned car and strange wooden debris are among the scattered remains of the old sand and gravel quarry.

Spiral labyrinth hidden in the hills above Oakland, CA.

Odd stone and concrete monuments in the "Poet of the Sierras" eclectic folly garden.

The neighborhood church casts a breast-shaped shadow that locals have come to call the “two o’clock titty.”

A mysterious painting of the self-declared Emperor of the United States watches over a local hof-brau.

A speck of nature and art in one of San Francisco’s most notorious neighborhoods.

Where a demonstration led to equal rights for one of California's most marginalized communities.

A hidden subterranean installation offers a view of the sky.

Art in the form of a winding, man made crack in stone.

A masterpiece in Golden Gate Park by virtue of the artist’s debt.

San Francisco's first World's Fair, dedicated to the wonders of California.

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

This bronze statue commemorates the strange and beloved mascot of UC Irvine—the only university to be represented by a giant anteater.

The shop's owner has spent decades in the desert wearing nothing but a strategically placed sock.

Adolph Sutro's little-known, geographically inaccurate, deprecated monument.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

Concrete strongholds stand guard over the Golden Gate.

This Alamo Square mansion is rumored to have hosted satanic rituals and other occult practices.

Gold Rush-era tombstones line the park's paths.

One of few lasting examples of the brief octagon craze that developed into folly.

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

A huge musical instrument played by the ocean.

A four paneled, brightly multicolored mosaic adorns the side of this popular grocery store.