Building Overview Technologies Game Strategies History
The Fortress is the third Fort-type building, upgraded from Castle at the Enlightenment Age Enlightenment Age once Military Military 4 (Conscription) is researched. It is automatically upgraded to Redoubt at the Modern Age Modern Age once Military Military 6 (Nation-in-Arms) is researched.

When upgraded from the Castle, the Fortress gains +900 hit points, +1 armor, +1 range, +2 line of sight and +20 Metal Metal plunder value.

For general information on Fort-type buildings, see Forts.