The woman after whom the palace in Rome was named is Margaret of Austria, an illegitimate daughter of Holy Roman Emperor Charles V (Charles I of Spain).
In 1536, at only 14 years of age, she was married to Alessandro de' Medici, duke of Florence, but a year later she was already a widow. She then married Ottavio Farnese, heir of the Duchy of Parma and Piacenza. Margaret lived in the Roman palace for about thirty years, from 1538 to 1559 and then again between 1567 and 1580. The intervening years were spent in the Netherlands, where she revealed considerable skills in her role as governor, an office to which she had been appointed by her half brother, Philip II of Spain.