A monumental cross hides in the trees in Golden Gate Park.

San Francisco’s century-old Christmas Tree.

The remains of a 12th-century chapter house in Golden Gate Park.

Radioactivity still cause for concern at this urban explorer's paradise.

Depicting scenes of everyday life - and specific individuals - in Great Depression era San Francisco.

A quiet marker in memory of local men and women lost in WWI.

A miniature view of the park, caught in time.

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

A rococo retro-futurist future-rustic vernacular between yesterday’s tomorrow and the future that never was.

A century and a half of research in the sciences and natural history, still going strong.

A classic advertising icon immortalized in regal bronze.

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

Thirteen trees representing the original thirteen colonies were planted with soil from historic Revolutionary battlefields.

A pair of mutilated bronze octopuses slump at the base of the monument honoring California's admission to the U.S.

This teeny-tiny park built by a San Francisco man in 1962 is mostly stairs.

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

A tribute to the artist and activist who created the rainbow pride flag.

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

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.

One of the smallest parks in San Francisco honors the legacy of the "Mother of Civil Rights in California."

For nearly 50 years, this San Francisco nonprofit has been serving as a mix of recycling center and art school.

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

This colorful boulder serves as a canvas for political statements and artistic expression.

Around the perimeter of San Francisco’s second-largest park is a meandering 2.7-mile path designed to inspire contemplation.