Vintage workers

The photo below is from an early, undated real photo postcard.  While it was never mailed there is a penciled note on the back saying that brother Frank is sitting in the front row on the right with the men he worked with, so we know that is a picture of Frank.  I do not know the date of the photo but am guessing it is either pre-1900 or shortly thereafter.  I cannot tell what the industry is.  The very dark background appears to be a large building, with perhaps a windowed clerestory at the top resulting in a lot of light there.  It appears that the men in front left are sitting on a short 2-wheeled cart, and frank is sitting on a wooden box.  The man standing on the left is wearing a long coat not unlike the ones worn in foundries or steel mills.  All of the men are all wearing hats which was typical of early workers.  The man sitting second from the left appears to be wearing a tie so he may be the boss, or the boss may be the man standing 3rd from the right who appears to have a pocket watch in his vest pocket.  I find old photos fascinating.