The Upgrade Kit is an item that can be used by its owner to upgrade an eligible special building to a higher level. Upgraded buildings get more powerful with each level. Each kit can only be used once.
To upgrade a building, use the upgrade kit item on the corresponding building that is already situated in your city. After the Upgrade Kit has been used some of the buildings will be stored in the inventory and must be placed in the city manually. Others will be placed directly on the same spot in your city and the production timer will not be reset. Buildings that become larger in size will be stored, buildings that keep the same size or become smaller will stay in your city.
Note that the upgraded building will be from your current era, even if the old one was from one of the earlier ages.
Shrink Kits are in essence like upgrade kits however they only reduce the size of the buildings and do not increase the production properties.
Some buildings can be upgraded without the upgrade kit. For example the Confectionary and the Tree of Love. Although they can be upgraded the mechanics are different. There is no upgrade kits for those buildings, instead players had to trade in the previous version of the building to receive the next version as part of the event questline they were part of.
For more information see the Graveyard.
The Graveyard is a special cultural building first given as a reward during the 2012 Halloween Event. The Graveyard received a yearly upgrade up until the 2017 Halloween Event when it reached level 6 Necropolis. 2018 Halloween Event introduced the Graveyard selection kit, no new level was added to the graveyard.
For more information see the Maypole.
Cider Mill Upgrade
For more information see the Cider Mill.
The Cider Mill is a special production building released during the 2016 Fall Event. Upgrades for level 2 to 4 were released a year later during the 2017 Fall Event. The highest version of level 5 was released during the 2018 Fall Event.
Pillar of Heroes Upgrade
For more information see the Pillar of Heroes.
Grand Bridge Upgrade
For more information see the Grand Bridge.
Cherry Garden Set Upgrade
For more information see Cherry Garden Set.
The Cherry Garden Set was released during the 2017 Spring Event. The upgraded version was released a year after during the 2018 Spring Event. During the event players were able to earn selection kits for each of the set building. Each selection kit had a corresponding upgrade kit as one of the options.
Tholos of Idols Upgrade
For more information see the Tholos of Idols.
The Ship Upgrade
For more information see The Ship.
Mill of Fall Upgrade
For more information see Mill of Fall.
Victory Tower Upgrade
For more information see Victory Tower.
For more information see Watchfire.
Winter Spire Upgrade
For more information see the Winter Spire.
For more information see the Yggdrasil.
The Yggdrasil is a special residential building given as a reward for finishing a Viking settlement. The building has total of 9 levels. To get the upgrade kits players need to finish the Viking settlement over and over again as shown in the settlement rewards.
Greater Runestone Upgrade
For more information see the Greater Runestone.
The Greater Runestone is a special residential building that is only obtainable by collecting fragments of the The Greater Runestone Selection Kit, given as a time reward for finishing a Viking settlement within a certain amount of time. The building has total of 5 levels.