Castle with a Tower

My third model I am doing for the project is a castle that I am using as environment to set the scene as 15th century Italy. I am modelling it after Vincigliata Castle, which is a medieval castle located in the region of Tuscany. The images I am using as reference are:

I started the model with the tower in one of the corners of the castle, and it didn't go too badly considering it was my first proper attempt at modelling a building. For the shape I just used a box and extruded polygons and edges where needed. I also used the bridge tool to create the slants on the top of the tower. To create the windows I cut out polygons (using the cut tool while in editable poly) where needed so that I could get that arched shape, and extruded them inwards and I did the same for the frame of the window. I used a darker brick texture for the main building and a slightly lighter brick texture for the window frame and accents.

Once I had the tower done, I made 4 more boxes for the rest of the castle and did mostly the same thing with extruding and cutting polygons. The thing I dislike most about it is the lack of detail; it's just a building with no real atmosphere. I also don't like that the windows are just black but I couldn't figure out how to make a hole all the way through the building and cap off the inside so you couldn't see inside the wall. Before I start animating, I want to edit this model more so that it has more life, and so you can see inside the windows and for there to be an actual doorway. I would also like to tweak the vertices so that lines aren't completely straight, so there are some bumps and tears in the castle walls, to add to the realism.