This may end up being one of those photos that we never figure out.
Dave Parker questions the date of the photo, and the age of the cars would suggest it was more around WWI. Additionally, from what I could determine, the girl on the poster on the end car was used on multiple posters form around 1900 through WWI (may have been used later, but I couldn't find any dated later).
The fact that the poster is on the car, and not the building, is very interesting. As far as I know, that would make the car ineligible for interchange, which lends weight to Ken Akerboom's comment about the cars possibly being used for "permanent" storage. If that was the case, then 1935 would be probable for the date of the photo.
I am leaning towards agreeing with Douglass Harding that this structure has to do with byproducts. His observations about that are logical.
Finally, the brick chimney looks like it was built prior to the covering over the track. My guess is it was for heating in the building. It almost looks like it is used to help hold up the shed, but you can see a partial gap at its top, which says to me it is not holding any of the load. Makes me wonder if the chimney was still in use at this time. If it was, then some (or all) of the smoke would end up under the shed.
Probably the best way to resolve all of this is if anyone can determine anything based on the cars in the background. Will be interesting to follow other's comments on this one.
-- Bill ParksCumming, GAModelling the Seaboard Airline in Central Florida