Princess Castle is a subtheme of Duplo that consists of 6 sets that ran from 2005 to 2007. Most sets were released in 2007 which accounted for 3 sets. As of today, the average annual growth of sets in Duplo Princess Castle is approximately 6.8% per year.
The LEGO Duplo Princess Castle theme, active in 2005, featured sets designed to appeal to young children with a fairytale and royal theme. Key sets include "Princess' Palace" (4820), which features a large, colorful castle with turrets, a princess figure, and various accessories; "Princess Royal Stables" (4828), which includes a stable, horse, princess figure, and grooming tools; and "Princess' Horse and Carriage" (4821), which comes with a princess figure, horse, and a carriage. These sets were designed to encourage imaginative play centered around royal and fairytale scenarios.