Hollow Bastion is a world that appears in Kingdom Hearts, Kingdom Hearts Final Mix, Kingdom Hearts: Chain of Memories, Kingdom Hearts Re:Chain of Memories, Kingdom Hearts coded, and Kingdom Hearts Re:coded.
Its name means 'Empty Castle' meaning that during one point, Hollow Bastion waas devoid of life except for the Heartless that dwelled there.
Ansem the Wise is the former ruler of this world. The castle was taken over by Maleficent and she proclaimed herself ruler until her defeat in Kingdom Hearts. Since both of them are no longer in power, the Hollow Bastion Restoration Committee seems to be in charge of the world.
Sora and the rest of the party enter Hollow Bastion at the Rising Falls and Sora, after a funny feeling in his heart, says he has been there before but ultimately knows he could not have visited Hollow Bastion before. Sora, Donald and Goofy meet up with Riku and The Beast. Riku tells Sora he is not meant to save Kairi and takes the Keyblade from him. Donald and Goofy follow the King's orders and follow Riku, who know has the Keyblade. Sora, feeling hurt, picks up his wooden sword and travels with The Beast till they arrive in the Entrance Hall. The Beast sees Belle and after Belle transforms into a Shadow Heartless, The Beast, out of rage, charges after the Heartless. Sora is then confronted by Riku, Donald and Goofy. Sora tells Riku that he doesn't need the Keyblade. His friends are his power. The Keyblade then returns to Sora and Riku channels the darkness within him and fights the trio only to lose. Riku leaves but is then taken over by Ansem: Seeker of Darkness. The Beast returns and Sora, Donald, Goofy and The Beast progress farther into the castle. They soon meet up with Maleficent who gets stabbed in the chest by Riku or Ansem: SoD. Once Maleficent disappears, Riku-Ansem reveals who he is and who Kairi is and what his plan is. Kairi's heart responds within Sora and Sora fights Riku-Ansem to protect Princess Kairi. Sora wins and Riku-Ansem disappears, leaving behind his Keyblade. Sora, releases his heart and Kairi's and the other Princesses of Hearts hearts as well. Kairi reawakens and sees Sora disappear. Riku-Ansem then returns as Ansem but Riku comes back briefly and tells Kairi, Donald and Goofy to run. They do and arrive back at the Entrance Hall to see a lone Shadow Heartless following them. Kairi realizes it is Sora and hugs him and he returns to normal. Sora and co. return to where they last saw Ansem and go to seal the Keyhole after fighting Behemoth. Leon and co. arrive and tell Sora that once the worlds are restored so will the walls that keep each world seperate and not even the Gummi Ship will work. Kairi and Sora make a promise that no matter where they are, they are always with each other. Sora and co. then leave to head for the End of the World world.