House of Borgia
However, the death of Pope Sixtus IV in 1484 weakened the House of Riario. In 1499 Pope Alexander VI, member of the strong House of Borgia, created the title of "Duke of Romagna" (uniting the lordships of Forlì, Imola, Faenza, Cesena, Ravenna and Rimini) for his illegitimate son Cesare Borgia, and the Riario family removed first to Bologna, then also to Rome and Naples.