The Duchy of Florence (Italian: Ducato di Firenze) was an Italian principality that was centred on the city of Florence, in Tuscany, Italy. The duchy was founded after Emperor Charles V restored Medici rule to Florence in 1530. Pope Clement VII, himself a Medici, appointed his relative Alessandro de' Medici as Duke of the Florentine Republic, thereby transforming the Republic of Florence into a hereditary monarchy.
The second Duke, Cosimo I, established a strong Florentine navy and expanded his territory, purchasing Elba and conquering Siena. In 1569, the Pope declared Cosimo grand duke of Tuscany. The Medici ruled the Grand Duchy of Tuscany until 1737.