Castle Oblivion

Castle Oblivion is a world in the Kingdom Hearts series. Castle Oblivion was once the Land of Departure, but after Master Earqus was struck down and the Land of Departure was destroyed, Aqua was given orders from her master to use his Keyblade to seal the world's keyhole, and as a result, the world was recreated into Castle Oblivion. The castle also contains the The Chamber of Waking, where Ventus' comatose body rests. Years later, Xemnas entrusted the castle and Naminé to Marulxia, who would use both to overthrow the Organization. Sora, Donald, and Goofy went inside the castle in search of Riku and King Mickey. But as they went higher and higher up, they were slowly loosing their memories, as part of Marluxia's plan. But his plan failed, and Sora, Donald, and Goofy went to sleep in three pods in order to have their memories be restored by Naminé.

Trivia

 * Jaden, Jeffrey, and the team may one day visit the castle.