The Koopa Bros. Fortress is a fortress that was once the home for Bob-ombs, but now, inhabited by the Koopa Bros. in Paper Mario. Mario, Goombario and Kooper travel here to find the first Star Spirit. On the way, one of the Koopa Bros. traps them in a cell, where they meet Bombette, who makes an escape route by exploding. They reach the Koopa Bros., defeat them and rescue Eldstar, the first Star Spirit.