Articles and categories pertaining to different Fortresses of all factions are below.
(The cost of a fortress is always 5000.)
Fortresses are the center of every factions base of operations. At the fortress, builders and heroes are trained, upgrades are researched, and defensive expansions are constructed. Each faction is capable of researching a master upgrade that has game-changing benefits, which cannot be researched until a prerequisite upgrade is obtained. More than one fortress may be built, however they are quite costly. Some maps have a pre-existing and non-customizable fortress (like Minas Tirith or Helms Deep) which can only be used to train builders and heroes.
In games where Ring Heroes are enabled, the player brings the One Ring into the fortress once it is retrieved from Gollum (or an enemy who got to him first). Once it has been placed in the fortress, a halo of elvish words from the ring appear above the fortress, signaling to all enemies where the One Ring has been placed, and that fortress is now able to train Sauron or Galadriel (depending on the faction). Once trained, the One Ring leaves the fortress with the hero who, if killed, drops the ring again.