Denny, terrific job of sleuthing. I remain mystified, if a building was constructed on that site why it would be torn down? Costly to build and costly to remove unless it was damaged beyond use by fire. I searched the aerial photo series amongst the OpenSFHIstory collection. From 6/27/1969, section 62 of 284 images shows the lot at the SW intersection of 25th & Noriega remains undeveloped at that time. You S.I. alums from that period will be curious to see the ’new campus’ that also appears in this image.