Princess Peach's Castle is a boss that appears in Mario & Luigi: Bowser's Inside Story. Princess Peach's Castle was powered up by Fawful after seeing Bowser getting closer. The Castle crushes Bowser forcing Mario and Luigi to head into the Rump Command and turn him giant. After a long battle, Bowser defeats Princess Peach's Castle and it reverts back to it's normal, yet now damaged, form.