Are those slots in the building "Archer's slots"? They sure look like that. That is quite a fortress.
I don't think so. The wall it's too thick and the slot too thin to be useful as Archer's slots. Seen from inside you can't spot anything outside nor try to aim. They more likely was provided only to let in the sunlight to illuminate tower stairs.
Anyway several studies have speculated that the Castle wasn't properly a fortress but something else. The position isn't strategically useful, the "Archer slots" are too thin to be used for weapons, there isn't any trace of a moat outside, and the spiral stairs turn counter-clockwise, in a way that would have obstacled defenders going down toward any attacker having the handrail to the right side instead of the left one, which would be better to keep free the right hand you use to grab the sword.
This probably was a recreation site where Frederick II recovered to study, meditate, and to rest between a battle and the other.
Or perhaps just a symbol of his presence in the land as it was clearly visible from great distance.
Someone even think that Frederick II never set foot here at all.
There is a lot of paper out about this site, I've bought some books there. I'm gonna tell you more as I go on with my reading...
