I know it is not always tactically a good move to go for huge cities, but it is interesting to see how big you can get them. I once got my Capital City up to population 26 (difficulty Noble) without consciously trying to make it bigger. What is the theoretical maximum if all the nearby improvements were farms, and how big have you managed to get your cities? Another unrelated question - if you build a city directly over a resource (e.g. oil) do you automatically get access to that resource as soon as you discover it, without having to build improvements?