Having taken power from the Republic of Florence after being elected as a supposed figurehead, he restored the power of the Medici, who thereafter ruled Florence until the last of the Medici Grand Dukes, Gian Gastone de' Medici (1671-1737). The governmental structures he set up endured past that, when it was absorbed into the Austro-Hungarian Empire.
Among his many accomplishments were the creation of the Uffizi, originally intended to house the government, and now one of the world's great art galleries; the creation of the Florentine navy, which played a key role at the battle of Lepanto; the expansion of Florence to control most of Tuscany, including Siena; taking over the Pitti Palace as a home for the Medici and finishing it off; the creation of the magnificent Boboli Gardens behind the Pitti; the promotion of the University of Pisa; and a host of other accomplishments in the economic, architectural and artistic spheres, including supporting Vasari and Cellini.
A large equestrian statue of him in bronze, by Giambologna, erected in 1598, still stands today in the Piazza della Signoria, the main square of Florence.
In 1537 the young CosimodeMedici (15191574) was plucked from relative obscurity in the Tuscan countryside to lead Florence after the assassination of his cousin Duke Alessandro deMedici (1511?1537).
Cosimos control of Florence was equally ruthless, but he eventually won the grudging support of the Florentine citizenrynot simply for the economic and political expansion he had garnered for the city but for its greater military security.
Cosimo appointed Niccolò Tribolo to redesign the gardens of the Medici villa at Castello (outside of Florence) and the Boboli Gardens (behind the Palazzo Pitti) with fountains, grottoes, water tricks, and areas of trimmed and wild plantings.