When it generates a map with a citadel, it is of a general size on the map (depending on small/medium/large) .. does the ruler scale make sense for that citadel, or is it suggesting that the citadel is massively huge or ridiculously tiny For example, according to Google Maps, Windsor Castle is about 450m end to end, Chepstow Castle is about 200m, and Dover Castle is about 100m (inner walls, or just 30m if measuring just the keep itself).
For small towns, the citadel building appears to be about 75m; medium towns have citadel castles of ~100m; and large towns have castles of about the same size. These are on the strangely large side.