There has been extensive discussion concerning the ultimate responsibility for the edifice, with critics attributing the onus of the design variously to Juan Bautista de Toledo or to Juan de Herrera. Despite some subtle qualifications, the 16th-century construction is characterized by its coherence and would seem to be the work of one team, led by the King. The building history suggests that Juan Bautista established the outlines of the design and that Herrera, who was trained by Juan Bautista, accepted the legacy and only introduced modifications.