Graeme Fernie, a reader in Australia, sends along this mystery photo that he found in an album that includes images of San Francisco. He says it’s labeled San Juan. Other scans from the photo album are here.
Notice the theater named the Hippodrome. Also the style of streetlamps (I don’t recall seeing this style in Los Angeles).
There’s also a Masonic lodge (note the square and compass) and a marquee.