I've been getting back into Civ4 the last couple months, and I'm trying to make the leap from Monarch to Emperor. I've read a good bit on the forums about the importance of specializing cities, and I think I get that as far as placing National Wonders and choosing between food/specialists and towns. What I don't understand so much is what to do with my cities once they've gotten obvious key buildings in place. I've read people saying I shouldn't build every building everywhere- but what should I do instead? For instance, in the mid-game,let's say one of my second-tier cities has a granary, library, forge, and courthouse. I'm not particularly close to the happy- or health-caps. I'm not planning a war in the immediate future. What should I build? Just keep choosing the next best city improvement until I've "built everything"? Build military units even though I suspect they'll be outmoded by the time I would want to use them? Or flip over to research/wealth? Any advice would be welcome!