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

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

The grand, column-fronted, sculpture-adorned home of the ambitious digital library.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

A huge musical instrument played by the ocean.

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

A library and museum dedicated to typography.

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

This contorting sculpture is the tallest in San Francisco.

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

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

The second building of its name to occupy this location might be the finest flatiron building in San Francisco.

This residential door allows San Francisco muggles a glimpse at the wizarding world.

The oldest dim sum restaurant in the United States is a nostalgic jewel.

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

One of the oldest producers of hand-folded fortune cookies still uses its original secret recipe.

Faceless white figures loom over the city from the rooftop.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

The randomness of this wall of lava lamps helps encrypt up to 10 percent of the internet.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A psychedelic labyrinth on the San Francisco bay.

Recovered from the brink of extinction, at home in the Financial District.

A Barbary Coast watering hole built into a Gold Rush shipwreck.

This (occupied) house is 10 feet wide and full of spite.