A favorite photo of my Dad and some pals on a hill in a very un-treed Central Park, probably about 1942. (He’s on the left.)
I believe the two-towered building back behind them is the San Remo building, which you can read more about on this Flickr page if you are so inclined.
So, I’d guess they are probably standing somewhere in line with 65th Street or so.
I’ll have to check out that spot next time I am in the neighborhood and see if I can find that hill.