San Francisco's secret public spaces that are privately owned

Marylin sez, "Even people living in San Francisco may not know there are 68 semi-secret privately owned public spaces in the city, and that's why the concerned citizens of SPUR (San Francisco Planning & Urban Research Association)has made a map that shows the locations of 45 of them, with short descriptions. A POPOS can be indoors or outdoors, on rooftops, past security guards, or beyond unmarked doors; some have been around since 1959; some are barren but others feature public art, fountains, and seating. These public spaces are (perhaps deliberately) not well marked, but the work of SPUR, recently published on Strange Maps, should help people find them."

441 – Sense of POPOS: Secret Spaces of San Francisco

(Thanks, Marilyn!)