Young Lucrezia (1974)

In the early-16th century, the mighty Borgia family, Cesare Borgia and his pitiless sister Lucrezia rule all Italy. Cesare, incestuously in love with his sister, commits a crime and starts a war campaign in Romagna. Lucrezia, meanwhile, gets pregnant. Cesare returns victorious from the war, and the Pope is then forced to separate his two children.