After seeing the keys in the wooden box, Donald could not help but reveal some eagerness in his eyes. It was not that the diagram he had was useless. The 36 Magic Towers of the Sky Castle were supported by the Sanctuary powerhouses of the High Elves in the past. There had to be plenty of incomparably precious treasures in there.
More importantly, Archbishop Martin also said that the 36 sets of keys were only a part of it. Hence, could there be more keys that could be used to open the other doors in the Sky Castle? Of course there were. The Magical Thousand-contraption Lock could not be opened just by using keys. There was a special unlocking method for every lock. Archbishop Martin should have mastered those unlocking techniques as well. Otherwise, those keys would only become garbage, and there would be no need for him to take them out.