Thanks to a Mission Mission, I found out this very interesting bit about a Southern Pacific Railroad line that used to run through the Mission District. I know railway and light-rail lines once criss-crossed this City, but this is particularly interesting.
I walk past the Juri Commons "park" nearly every day (and twice a day at that). It has always been slightly baffling to me and I long suspected a MUNI railway line ran down it's corridor. But now I know better and a better man I am for knowing.