The Exile Fortress is a location in Xenoblade Chronicles. It is located in Satorl Marsh, east of the Dark Swamp, southeast of the Silent Obelisk, west of the Glowing Obelisk and north of the Igna Territory.
The altar is on the roof. It can be reached by using the secret door, which is behind the throne. After completing The Giants' Treasure, the next time the party nears the altar, the Eternal Palsadia will appear and attack if it hears the party run or walk.
The back door can also be used to enter the fortress, but the Rear Door Key is necessary.