The second level of the Castle was quick and simple to create, using just the roofs of the courtyard buildings, and focusing on the living quarters for the staff and owners. On my original drawings, I had tree stumps on the first floor, and full leaf foliage on the second to show detail by leaving (ahem) the road off for clarity.
I felt early on that a simple design would work well because I didn't feel a full blown castle with all the trimmings fit TCotBO. My original map has a scrawling script across the top:
"Twin circular towers with square central building"
Presented below is the second floor of the Castle Complex: