Castle Oblivion is a mysterious fortress featured in Kingdom Hearts: Chain of Memories. The castle itself has twenty-five floors, twelve of which are basements. The lord of the castle is Marluxia, a member of Organization XIII. The castle is decorated with a rose motif, probably because Marluxia is a master of the flower element.
Castle Oblivion is dominated by the use of cards. When entering the castle, one's memories and abilities are quantified into cards. Castle Oblivion's floors can be transmuted into different forms and layouts through the use of "world cards" derived from one's memories, as well as "map cards" which determine the properties of individual rooms.
World cards based on Agrabah, Olympus Coliseum, Wonderland, Monstro, Atlantica, Halloween Town, Neverland, 100 Acre Wood, Traverse Town, Hollow Bastion, Destiny Islands and Twilight Town have been created from Sora's and Riku's memories.