I can’t believe I’ve never visited Duboce Park. I ride past there many times on the N Line Metro, but I’ve never stopped to walk around. It’s a really nice little dog friendly park. It rhymes with those and not with cozy, and Wikipedia says it’s “one of the few parks in the city without a roadway or walkway separating the park land from buildings.” I found some vintage pictures of Duboce Park and went over there last Thursday to do some then and nows. (Thumbnail images)
The difficulty with updating vintage pictures of Duboce Park is that I couldn’t find a lot of old photographs of the actual park; most vintage photos are looking toward the Sunset (or Duboce) Tunnel on the south side of the park. I wasn’t able to match up the location of this old photograph of Duboce Park from the San Francisco Public Library Archives. It was probably taken looking east toward Steiner or south toward Duboce, the only views that could have street traffic in the background, but the buildings don’t match up. My picture is looking northeast across the park.
Addendum: That’s the Mint Building in the upper right of the vintage picture. The view is northeast across Steiner, just to the right of my picture.
I may have gotten a match up with this circa 1910 photo of the park with my picture looking southeast; the four houses in the upper right do match up with the houses behind the trees in my photo. Check out those interesting rock formations in the vintage photo; one person’s artistic landscape, another person’s liable for injury lawsuit. (San Francisco Public Library Archives)
Looking west toward the Sunset Tunnel in 1935: The Muni Metro N Line runs through here now. (opensfhistory.org)
Another view looking west toward the streetcar tunnel in 1963: (opensfhistory.org)
Looking southwest toward the tunnel in 1964: Duboce Avenue is on the left. Buena Vista Park is in the background of all of the streetcar tunnel pictures.
San Francisco Film Locations Then & Now 
Goodness, that is a significant volume of stone, and it seems like an odd landscape feature for that time. My first thought was that it could have been unrecyclable Earthquake debris that was incorporated into the landscape so that it did not need to be hauled to an already overwhelmed landfill on San Francisco Bay. (I can remember a picture of such piles at Stanford University. Some of the stone was eventually recycled into new buildings. Some that was too pulverized to be recycled was incorporated into landscape features, or merely buried within low areas that were elevated and leveled by fill.) However, it does not appear to be shaped stone from buildings. Furthermore, the neighborhood does not seem to be the sort that included stone buildings that were big enough to generate so much unrecyclable debris. The stone does not seem to be a natural outcropping; and if it were, some of it might have been incorporated into the landscape that is there now. If the ground there is naturally rocky, the Park, prior to development, could have been a site where stone was dumped from surrounding parcels as they were developed into homes.