Note that the upgraded building will be from your current era, even if the old one was from one of the earlier ages. Buildings that become larger in size will be stored, while buildings that keep the same size or become smaller will stay in your city. After the upgrade kit has been used, some buildings will be stored in the inventory and must be placed in the city again manually others will be placed directly on the same spot in your city, and the production timer will not be reset. To upgrade a building, the upgrade kit must be used on the corresponding building that is already situated in the city.

Upgraded buildings gain better properties with each level.

(and too many bp-oh well.The Upgrade Kit is an item that can be used to upgrade an eligible special building to a higher level. For a tiny fp investment, you can get extra fp back plus medals. These guys who do not know how to defend themselves also have non-optimal investment of their fp-putting them into their OWN GB instead of others. Special note to you other plunderers: I have invested fp for the best plunder. They have not appeared very much this year, and to some extent, you have to give up better prizes to get them. I only have one Watchtower, which I got in the carnival event. Those are harder to find space for than watchtowers. But I took mine down in Late middle ages, because Ritual Flames are a better use of space and I have more of those than I need. In EMA, when you get the monastery, that 20% was huge, almost enough to stop me by itself. About 50% will stop me, and 30% defense is a deterrent.

I am the worst plunderer I have seen, but I am in Colonial Age. Click to expand.This sort of numbers depends on the age you are in.

Forge of empires watchfire