The Main setting is the Castle where everyone lives. The king, his daughter, the servants, and all of the mice live in the same castle. All of the mice live in the holes that are in the walls while the rats live in the dungeon. Also, the castle represents the light and dark in the world because the dungeon is dark and lots of lives were killed there, and the dungeon is like one big maze because of all the tunnels there so only the rats know their way around since they live there for their whole lives.
A theme of The Tale of Despereaux, by Kate Dicamillo, is that you have to learn to respect yourself because society won't respect you and they won't show kindness towards you because are different.
Individuality
Fear
Trust
Unloved
Family