The One Market Plaza building armors its public space along Mission Street by folding up and locking most of its benches during non-business hours. [To clarify: we found these benches locked on a Sunday afternoon. I don't know the exact hours they are locked.]
Here's the Sunday afternoon look of the place.
By the way, that colorful bit on the far corner is the 1934 Bloody Thursday monument.
I'm adding the "Lunching in Public" tag to this item but in truth it didn't occur to us to eat lunch here. We clearly weren't welcome. We kept walking and ate at the Ferry Building.