Castle Oblivion was initially the world Land of Departure. After the defeat of Master Eraqus at Terra's hand, Master Xehanort summoned the darkness to destroy the land.The castle was eventually found by Xemnas of Organization XIII, who decided to convert it into a second headquarters for the Organization. It was intended to be a place to research memories, an important topic to the Nobodies of the Organization, who have only their memories to form personalities with.
