Florence was the site of an Etruscan settlement and later became a Roman town on the Cassian Way (the modern Piazza della Republica is on the site of the Roman Forum). In the 5th and 6th cent. A.D. the city was controlled, in turn, by the Goths, Byzantines, and Lombards. It became an autonomous commune in the 12th cent.
In the 13th cent. the Guelphs (who were propapal) and the Ghibellines (who were proimperial) fought for control of the city. By the end of the 13th cent. the Guelphs held control, but they then split into warring factions, the Blacks and the Whites, best remembered because Dante, a Florentine, was banished (1302) as a White Guelph. Warfare raged, too, with other cities, notably Pisa, as the merchants and bankers of Florence made their own fortunes and that of the city; the sale of Florentine silks, tapestries, and jewelry brought great wealth. Florence grew as a result of war, absorbing Arezzo, Pistoia, Volterra, and Pisa. Growth was temporarily halted in 1348, when the Black Death killed approximately 60% of the city's population.
Florence became a city-state and in the 15th cent. came under the control of Cosimo de' Medici, a wealthy merchant and patron of the arts. Although republican forms were kept until the 16th cent., the Medici family ruled, and Lorenzo de' Medici, who held power from 1469 to 1492, was able to put down the Pazzi conspiracy (1478), instigated by Pope Sixtus IV.
Under Lorenzo and his successors, Florence was for two centuries the golden city, with an incredible flowering of intellectual and artistic life. The list of artists working in the city was headed by Michelangelo, Leonardo da Vinci, Raphael, and Donatello. There were also numerous poets and scholars active in Florence, and the Accademia della Crusca was established (1582). A school of music flourished in the city during the Renaissance, and the earliest operas, Peri's Dafne (1594) and Euridice (1600), were performed there.
Political life continued to be turbulent. The Medici were expelled by a revolution in 1494, the fiery religious reformer Savonarola briefly held power (1494–98), and Machiavelli was a diplomatic representative of the republic. The revolt against the Medici was over by 1512, but another revolution (1527–30) established a new republic, which, however, was forced to surrender to Emperor Charles V after a heroic defense.
Under the restored Medici, Florence went on expanding and controlled most of Tuscany. In 1569, Cosimo I de' Medici was made grand duke, and Florence became the capital of the grand duchy of Tuscany. The grand duchy, ruled by the house of Hapsburg-Lorraine after the extinction (1737) of the Medici line, was annexed to the kingdom of Sardinia in 1860. Florence was the capital of the newly founded kingdom of Italy from 1865 to 1871. Relatively few of the art treasures of Florence were harmed in World War II; the flooding of the Arno in Nov., 1966, however, caused extensive damage, which art experts sought, with considerable success, to repair.