Found more of these urban plaques on the street and in my photo collection. I’ll post more as I find them. I’m very curious what their exact purpose was. I’m sure it was for some kind of measurement, but the odd thing is is their placement. Some are only a block or two away from each other. Others are in different neighborhoods altogether. Maybe I’ll post a map of where I find them and see if there is some kind of pattern. Also, if you see these on the street, please let me know where so I can go take a shot of them.