is the third Fort-type
building, upgraded from Castle
at the Enlightenment Age
once Military 4 (Conscription)
is researched. It is automatically upgraded to Redoubt
at the Modern Age
once Military 6 (Nation-in-Arms)
When upgraded from the Castle, the Fortress gains +900 hit points, +1 armor, +1 range, +2 line of sight and +20 Metal plunder value.
- For general information on Fort-type buildings, see Forts.