If this mod is on, then you can build Guard Towers on Villages, to do so the village should belong to you and have no any unit on it, then through right-click context-menu can order an Guard Tower to be built there for 16 gold. The Guard Tower is a stationary level 1 mechanical unit with 45 hp, that is of neutral alignment and does not incur upkeep, has a vision radius of 3, can use 10 dmg-1 strike ballista and 4 dmg-3 strike archery attacks at range, has no melee attack and 0% resistance against any type of damage.
Building an Guard Tower on a village denies your opponent the capture of this village, for the drawback that yourself cannot use the village for healing either aslong the Guard Tower stands on it.
Update 1.1: Tweaked stats of the Guard Tower.
Update 1.2: minor bugfix.
Update 1.3: Ensured compatibility with my 'Lootable Villages' and 'Healing Tent' mods. Guard Towers cannot raze the village they are on. An Guard Tower cannot get built on Healing Tent. Added new menu icon.