Ultimecia Castle (アルティミシア城, Arutimishia-jō?) is the final dungeon of Final Fantasy VIII. The main antagonist and final boss, Ultimecia, resides deep within the castle. The monsters fought within the castle have random levels. Transport to and from Ultimecia’s world and the normal world can be done via four portals outside the castle, which lead to various locations on the world map.
Squall and his friends travel to Ultimecia Castle in the future when Ultimecia compresses time into a world where only she can live. Time compression never fully occurs — it is temporarily halted by Ellone — and the party counteracts it by believing each others’ existence.
Upon confronting Ultimecia in the clock tower Ultimecia doesn’t act surprised, as if she has been waiting for them to show up. She only comments laconically that the party must be the “Legendary SeeD” she must face. Ultimecia reaches into Squall’s mind to find out the strongest force he can visualize and creates Griever from Squall’s impression of an ultimate Guardian Force, summoning it against him and his friends. The party perseveres and Ultimecia eventually begins to absorb all of time and space into her body to become a living god. The SeeDs destroy her and Ultimecia evaporates in a large explosion, sending her body along with Squall’s forward in time. The others find their way back to their world by believing in each other’s existence and focusing their thoughts of a place they want to return to.