[3] Later he bought the unfinished Pitti palace with his wife's money, finished it, and moved there.

Meanwhile he was strengthening his position in every way by alliances and treaties, and also by the convenient murder of Lorenzino, the Brutus who had rid Florence of Alessandro ten years earlier, and whose presence in the flesh could not but be a cause of anxiety since Lorenzino derived from an elder son of the Medici, and Cosimo from a younger.

In 1555 the ancient republic of Siena fell to Cosimo's troops after a cruel and barbarous siege and was thereafter merged in Tuscany, and in 1570 Cosimo assumed the title of Cosimo I, Grand Duke of Tuscany, and was crowned at Rome.
Whether or not the common accusation against the Medici as a family, that they had but one motive--mercenary ambition and self-aggrandisement--is true, the fact remains that the crown did not reach their brows until one hundred and seventy years from the first appearance of old Giovanni di Bicci in Florentine affairs.

The statue of Cosimo I in the Piazza della Signoria has a bas-relief of his coronation.

He was then fifty-one; he lived but four more years, and when he died he left a dukedom flourishing in every way: rich, powerful, busy, and enlightened.