stronghold is neat. its a bit old and the graphics are outdated but its pretty much exactly what you said. you are put on a map, you have to build a small functioning society, walls, towers, have people who make weapons, armor, make military units, and defend your castle. its pretty neat because unlike most games, its not about offense.. its about complete defense. there is some goal or time limit you have to survive and basically you got to survive it and accomplish whatever goal you have to do while holding off wave after wave of armies. its not like ceasar 3 though but i think it might interest you. check out some professional reviews or a demo or somethin. as for stronghold 2.. i heard it isnt that great.. might as well stick with the first one.
another game that is awesome is rome: total war. its not like ceasar 3 where you have to place buildings and stuff.. its more along the lines of a world view. you build buildings, train units in specific cities. you then use units to defend or move about the map. whenever a city gets attacked you have to defend it. have archers on the walls, calvary, etc. if you attack cities, you have to lay siege to them and take their walls, kill off all their units and/or take the town center. then you can choose to kill their population, slave them, burn the city, capture it, etc. its a very large scale war too. you dont control single units, instead you control legions of units. aka a single unit of calvary is about 30 horses i think.. a unit of cohorts (infantry) would have probably near 50 maybe more in a group. this game is very rock paper scissors too. if you attack infantry with calvary, its only a matter of seconds before they get routed. if elephants (from carthage) attack infantry, then you are completely annihilated. spearmen take out archers. heavy infantry takes out light.. you get the idea. its very realistic. the battles are very neat lookin too. i would say this game is more of a empire building game rather than a city builder. i think it might interest you though.
thats pretty much all i got for ya.. if i think of any more ill let you know.