If CTP2 is like previous civ-type games, then a granery is a MUST-BUILD first city improv since it halves how much food is needed to grow. Granerys and recycle centres are the only two improvs I definitely rush buy. Put them down as quickly as possible is my theory. I haven't read the manual yet so I can't know for sure if a granery works like this, but I always build a granery ASAP. Plus, it supposedly stops starvation (though I've never had starvation in a city under 30).
Rommell to a sub-commander outside Tobruk: "Those Australians are in there somewhere. But where? Let's advance and wait till they shoot, then shoot back."