Carlo,
This has taken two years to get this far. My guess is I have another three years. I am thinking three long barracks buildings around the parade ground. The first attempt at the barracks was judged a failure, and I am now back at square one with those. After Christmas, I may start again on the buildings. A fourth building may sit just outside the far wall - hospital.
Then the main gate, which ideally would have a drawbridge, plus a timber bridge over the ditch. You can see where the timber bridge would be in the top photo. The two sally ports are done - narrow passages through the walls. Top photo you can see a door leading to one of the sally ports.
On two of the sides, you can see a two by four inch wooden stud that the fort is sitting on. But on the top photo only, you can see that the far left wall is not on laying on a wooden stud. The two horizontal studs represents the sides of the excavated ditches. I am leaning towards the technique Mike illustrated using the plaster cloth to place over the wooden stud so that it looks like excavated earth, but that is maybe the last step.
If I was really smart, I would simply ship the fort as is to Mike;s place and have him finish it. Mike, the wood stain is Miniwax Gunstock and the finish is sem-gloss polyurethane.