Civilian structures, due to their extensive utility, are extremely complex to upgrade. The civilian research lab of a Tier 6 territory spent many years and only managed to upgrade all civilian buildings to Tier 4.
Only the quality of his own residential buildings was raised to Tier 5, but in fact, such an enhancement of power also leads to a significant overall improvement of his territory.
Not to mention, the enhancement of the quality of his subjects significantly reduced his expenses in training military troops.
Otherwise, relying only on the limited income from his territory, it would be impossible to construct a full force of troops.
Looking at the military structures, the Skybreaker Mage Tower and the Elemental Tower are both sub-buildings of the Mage Tower; thus, upgrading them is even more difficult, so they remain at Tier 5 and have no plans to upgrade to Tier 6 yet.
Rune City Wall (Tier 5):
