Castles! Envy of peasants, home of kings, castles are defined as any large building or group of buildings fortified by walls (the fortification is what differentiates a castle from a mansion). Many stories in the medieval ages, or which involve royalty of any kind, will take place at least partly in a castle, so ask lots of questions about castles to help build a template to design your own with! I find it helps to think of castles in real life and in fiction, note specifics about them, and work backward from there to generate questions. ie: A castle in Europe = What country is the castle in? Bring on the questions!