Central to every village, town, city, capital in Feudal times; was a place to worship. Christian, Pagan, and Mongolian (Tengri) structures should be an option since those correspond with the races in the game. Just like housing and keeps, it would be nice to have various sizes of structures. A small chapel for a village, a church for a town/city, and a Cathedral for a capital. The game already has Bishops, and a Pope. Now we just need a place for them. It would really spice up the village building since there really isn't an option for other types of buildings.
As mentioned in other topics, it would be the best and most logical place to put the city bell for warnings or alerting others around the area for whatever reason.