This rare example of a "tidefall" is a spectacular drop from the cliffs down onto the beach.

A sparse, solitary sequoia still stands as a living tribute to the famous conservationist who planted it—but it's dying.

Once the gateway to the utopian dream-village of a Civil War embalmer.

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

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

A huge musical instrument played by the ocean.

The remains of a ruined mansion memorialize the 1906 earthquake.

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

Where the alchemists dream of transmuting base metal into gold was actually achieved.

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

Barely visible foundations remain where Stow Lake’s “observatory” once welcomed visitors.

A hidden subterranean installation offers a view of the sky.

A brooding mansion of clinker brick stands out among the Victorian houses of Pacific Heights.

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

Olfactory delights in San Francisco's Botanical Gardens.

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

Golden Gate Park's historic collection of plants.

27-room home built with the fortune of a sugar magnate.

Forgotten and then destroyed by fire, this was once one of the largest saltwater swimming pools in the world.

A famous alternative culture epicenter and where Joplin serenaded young hippies.

An vast warehouse of everyday treasures in Berkeley, CA.

An overlooked and unassuming engineering marvel.

The only theatre in the world constructed specifically for sound movement.

An enormous artwork that colorfully celebrates over 150 years of US military achievements.