The House of Medici was a powerful banking family and patron of the arts and sciences. The ruling family of Florence for most of the 15th Century, and the first half of the 16th. The basis of their power lay in the foundation of the Medici bank by Giovanni de Bicci in 1397, which serviced the papacy. The Medici assumed the title of Dukes of Tuscany from 1530 and Grand Dukes from 1569 to 1737. Giovanni's son Cosimo I (1389–1464), was a great patron of the arts and humanism. Robert Dudley's ‘Arcano del mare’ was bound for Cardinal Gian Carlo de’ Medici (1611-1663), “High Admiral of the Tuscan Navy”, “General of the Mediterranean Sea” and “General of the Spanish Seas”. Gian Carlo was the second son of the dedicatee of the atlas, Cosimo II de’Medici, Grand Duke of Tuscany, and Maria Maddelena of Austria.