El autor estudia la figura de Alfonso X, rey de Castilla, y su entorno familiar. Su nacimiento y principales acontecimientos de su vida, su matrimonio y su descendencia legítima e ilegítima, haciendo especial hincapié en sus datos cronológicos y matrimoniales. Igualmente hace algunas reflexiones sobre su posición institucional en la monarquía castellana, durante el siglo XIII.

The author studies the figure of Alfonso X, king of Castile, and his family environment. His birth and main events of his life, his marriage and his legitimate and illegitimate offspring, with special emphasis on his chronological and marital data. He also makes some reflections on his institutional position in the Castilian monarchy, during the thirteenth century.