Here you can see an overview (very over, as high as I could reach, in fact) of the layout of the fortress. The upper left is the keep, the lower right the church. The barbican got chopped off a little on the left. It really got chopped off in the citadel's restoration, but more on that later.
Carcassonne has one of the most elaborate and impressive
defensive designs I've ever seen. Multiple high walls, plus being on a hill. Its greatest enemies were time, and the French government, which wanted to demolish it in the mid-1800s.
For this picture, I'd made a loop back round near where I started, coming
in under the keep. A small garden and benches are set up in the space that was
once designed to be a murder zone during defense of the keep.