From the fort you can make small army, giant cannon, and diggers. IF you went orient, then u can make an Oriental fort, I think at the 5th level of prestige u can earn by turning in those signed letters of friendship from your starting point empire npc town.
As a europe focused town u can make small army, big army, and trebuchet from the castle. When you reach Pat level in town's people, u get a castle, which is represented by a giant knight's helmet, u ca only make military from there, or from an assassin's building found on islands. Usually if u want noblemen in your town you'll need around 2.5k pat's, 1.5k citz, 1k peasants, and 500 at least beggars [by having beggars in your town in their Alms House, you automatically get more 'advancement' tickets to use to get to the next class of people in your town. Other then that, you might just need to increase the size of your town, usually for me, if my highest current class of towns people is around 1k and I want nobles, I usually need to build more housing, as it seems they made it to be somewhat realistic, in that u need a lot more of the lower class population to raise the population of the upper class by little.
If you get stuck, it's usually that your town lacks something the highest class of people in your town need.
