Castle upgrade requirements
Upgrading your castle level requires specific buildings to have been constructed first. The list below is a comprehensive list of all requirements for each castle level.
| Upgrade | Level | Required Building 1 | Required Building 2 | Level |
| Castle 3 | Wall level 2 | Lumber Mill | 2 | |
| Castle 4 | Wall level 3 | Quarry | 3 | |
| Castle 5 | Wall level 4 | Farm | 4 | |
| Castle 6 | Wall level 5 | Bowmen Barracks 6 | 5 | |
| Castle 7 | Wall level 6 | Hospital | 6 | |
| Castle 8 | Wall level 7 | Shieldmen Barracks | 7 | |
| Castle 9 | Wall level 8 | Academy | 8 | |
| Castle 10 | Wall level 9 | Cavalry Barracks | 9 | |
| Castle 11 | Wall level 10 | Warehouse | 10 | |
| Castle 12 | Wall level 11 | Spearmen Barracks | 11 | |
| Castle 13 | Wall level 12 | Wishing Fountain | 12 | |
| Castle 14 | Wall level 13 | Dwelling | 13 | |
| Castle 15 | Wall level 14 | Tower of Knowledge | 14 | |
| Castle 16 | Wall level 15 | Bowmen Barracks | 15 | |
| Castle 17 | Wall level 16 | Hospital | 16 | |
| Castle 18 | Wall level 17 | Shieldmen Barracks | 17 | |
| Castle 19 | Wall level 18 | Academy | 18 | |
| Castle 20 | Wall level 19 | Cavalry Barracks | 19 | |
| Castle 21 | Wall level 20 | Warehouse | 20 | |
| Castle 22 | Wall level 21 | Spearmen Barracks | 21 | |
| Castle 23 | Wall level 22 | Wishing Fountain | 22 | |
| Castle 24 | Wall level 23 | Tower of Knowledge | 23 | |
| Castle 25 | Wall level 24 | The Forge | 24 | |
| Castle 26 | Wall level 25 | Hospital | Bowmen Barracks | 25 |
| Castle 27 | Wall level 26 | Academy | Shieldmen Barracks | 26 |
| Castle 28 | Wall level 27 | Cavalry Barracks | Warehouse | 27 |
| Castle 29 | Wall level 28 | Spearmen Barracks | Wishing Fountain | 28 |
| Castle 30 | Wall level 29 | Tower of Knowledge | The Forge | 29 |
| Castle 31 | Wall level 30 | Hospital | Bowmen Barracks | 30 |
| Castle 32 | Wall level 31 | Academy | Shieldmen Barracks | 31 |
| Castle 33 | Wall level 32 | Cavalry Barracks | Warehouse | 32 |
| Castle 34 | Wall level 33 | Spearmen Barracks | Wishing Fountain | 33 |
| Castle 35 | Wall level 34 | Tower of Knowledge | The Forge | 34 |
| Castle 36 | Wall level 35 | Hospital | Bowmen Barracks | 35 |
| Castle 37 | Wall level 36 | Academy | Shieldmen Barracks | 36 |
| Castle 38 | Wall level 37 | Cavalry Barracks | Warehouse | 37 |
| Castle 39 | Wall level 38 | Spearmen Barracks | Wishing Fountain | 38 |
| Castle 40 | Wall level 39 | Tower of Knowledge | The Forge | 39 |
| Castle 41 | Wall level 40 | Hospital | Bowmen Barracks | 40 |
| Castle 42 | Wall level 41 | Academy | Shieldmen Barracks | 41 |
| Castle 43 | Wall level 42 | Cavalry Barracks | Warehouse | 42 |
| Castle 44 | Wall level 43 | Spearmen Barracks | Wishing Fountain | 43 |
| Castle 45 | Wall level 44 | Tower of Knowledge | The Forge | 44 |
| Castle 46 | Wall level 45 | Hospital | Bowmen Barracks | 45 |
| Castle 47 | Wall level 46 | Academy | Shieldmen Barracks | 46 |
| Castle 48 | Wall level 47 | Cavalry Barracks | Warehouse | 47 |
| Castle 49 | Wall level 48 | Spearmen Barracks | Wishing Fountain | 48 |
| Castle 50 | Wall level 49 | Tower of Knowledge | The Forge | 49 |