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.

A modern mechanical planetary system, part of a 10,000 year clock.

Once the fastest ship from San Francisco to Tahiti, the Galilee now lays in pieces in three different cities.

Visible below the waves are memorials to the city's Gold Rush dead.

The only visible piece of San Francisco's most famous shipwreck.

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

A hidden gem, named after a San Franciscan icon, offers spectacular views of the Pacific Ocean.

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

Big gun installations, built over a massive cemetery, now abandoned & hidden in trees.

A winding path built in secret on the edge of the continent.

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

A library built during San Francisco's pioneer times is a student's retreat, bibliophile's sanctuary, and chess player's delight.

A quiet nook at the top of a little-known hilltop park named after California's first poet laureate.

This bakery sits on the site of the Black Panther Party's first headquarters.

With statues of Nelson Mandela and Harvey Milk this monument has been called the Mount Rushmore of California.