Florence was founded in 59 BCE as a settlement for former soldiers and was named Florentia, allotted by Julius Caesar to his veterans in the rich farming valley of the Arno. The city was built in the style of a military camp with a castrum in a chessboard pattern and the main streets, the cardo and the decumanus, intersecting at the present Piazza della Repubblica, which can still be seen in the city center. Florentia was situated at the Via Cassia, the main route between Rome and the North, which position enabled it to rapidly expand as a commercial center. Emperor Diocletianus made Florentia capital of the province of Tuscia in the 3rd century CE.
While visiting the ruins of Rome during the jubilee celebration in 1300, the banker and chronicler Giovanni Villani (c. 1276–1348) noted the well-known history of the city, its monuments and achievements, and was then inspired to write a universal history of his own city of Florence. Hence he began to record—in year-by-year format—the history of Florence in his Nuova Cronica, which was continued by his brother and nephew after he succumbed to the Black Death in 1348. Villani is praised by historians for preserving valuable information on statistics, biographies, and even events taken place throughout Europe, but his work has also drawn criticism by historians for its many inaccuracies, use of the supernatural and divine providence to explain the outcome of events, and glorification of Florence and the papacy.
The seat of a bishopric from around the beginning of the 4th century CE, the city was alternatingly under Byzantine and Ostrogothic rule as the two powers fought each other for control of the city, taking it by siege only to lose it again later. The fighting over the city may have caused the population to have sunk to as few as 1,000 people.
Peace returned under Lombard rule in the 6th century. Conquered by Charlemagne in 774, Florence became part of the Margraviate of Tuscany, which had Lucca as its capital. The population began to grow again and commerce prospered. In 854 Florence and Fiesole were united in one county.
Margrave Hugo chose Florence as his residence instead of Lucca at about 1000 CE. This initiated the Golden Age of Florentine art. In 1013 the construction was begun of the Basilica di San Miniato al Monte. The exterior of the baptistry was reworked in Romanesque style between 1059 and 1128.
Reviving from the 10th century and governed from 1115 by an autonomous commune, the city was plunged into internal strife by the 13th-century struggle between the Ghibellines, supporters of the German emperor, and the pro-Papal Guelphs, after the murder of Buondelmonte from the Amidei for his missed promise to marry one from the Amidei family. In 1257 the city was ruled by a podestà, the Guelph Luca Grimaldi. The Guelphs had triumphed and soon split in turn into feuding "White" and "Black" factions led respectively by Vieri de' Cerchi and Corso Donati. These struggles eventually led to the exile of the White Guelphs, one of whom was Dante Alighieri. This factional strife was later recorded by Dino Compagni, a White Guelph, in his Chronicles of Florence.
Political conflict did not, however, prevent the city's rise to become one of the most powerful and prosperous in Europe, assisted by her own strong gold currency. The "fiorino d'oro" of the Republic of Florence, or florin, was introduced in 1252, the first European gold coin struck in sufficient quantities to play a significant commercial role since the seventh century. Many Florentine banks had branches across Europe, with able bankers and merchants such as the famous chronicler Giovanni Villani of the Peruzzi Company engaging in commercial transactions as far away as Bruges. The florin quickly became the dominant trade coin of Western Europe, replacing silver bars in multiples of the mark. This period also saw the eclipse of Florence's formerly powerful rival Pisa, which was defeated by Genoa in 1284 and subjugated by Florence in 1406 Power shifted from the aristocracy to the mercantile elite and members of organized guilds after an anti-aristocratic movement, led by Giano della Bella, enacted the Ordinances of Justice in 1293.
Of a population estimated at 80,000 before the Black Death of 1348, about 25,000 are said to have been supported by the city's woolen industry: in 1345 Florence was the scene of an attempted strike by wool combers (ciompi), who in 1378 rose up in a brief revolt against oligarchic rule in the Revolt of the Ciompi. After their suppression, the city came under the sway (1382-1434) of the Albizzi family, bitter rivals of the Medici. Cosimo de' Medici was the first Medici family member to essentially control the city from behind the scenes. Although the city was technically a democracy of sorts, his power came from a vast patronage network along with his alliance to the new immigrants, the gente nuova. The fact that the Medici were bankers to the pope also contributed to their rise. Cosimo was succeeded by his son Piero, who was shortly thereafter succeeded by Cosimo's grandson, Lorenzo in 1469. Lorenzo was a great patron of the arts, commissioning works by Michelangelo, Leonardo da Vinci and Botticelli.
After Lorenzo's death in 1492 and his son Piero's exile in 1494, the first period of Medici rule ended with the restoration of a republican government, influenced until his execution (1498) by the teachings of the radical Dominican prior Girolamo Savonarola, whose monomaniacal persecution of the widespread Florentine sodomy and of other worldly pleasures foreshadowed many of the wider religious controversies of the following centuries. However, in due time, Savonarola lost support and was burned at the stake.
A second individual of unusual insight was Niccolò Machiavelli, whose prescriptions for Florence's regeneration under strong leadership have often been seen as a legitimization of political expediency and even malpractice. Commissioned by the Medici, Machiavelli wrote the Florentine Histories, the history of the city. However, Machiavelli was actually tortured and exiled from Florence by the Medici family and the Pope under the pretense of sedition due to his ties to the previous democratic government of Florence and the fact that his work threatened to expose the true nature of their power base and they wished to discredit him. The Florentines drove out the Medici for a second time and re-established a republic on May 16, 1527. Restored twice with the support of both Emperor and Pope, the Medici in 1537 became hereditary dukes of Florence, and in 1569 they became the Grand Dukes of Tuscany, ruling for two centuries. Only the Republic of Lucca (later a Duchy) was independent from Florence in all Tuscany.
There was also a darker side to the Renaissance of Florence. Mobs were both common and influential. Families were pitted against each other in a constant struggle for power. Politically, double-crossings and betrayals were not uncommon, sometimes even within families.
The surge in artistic, literary, and scientific investigation that occurred in Florence in the 14th-16th centuries was precipitated by Florentines' preoccupation with money, banking and trade and with the display of wealth and leisure.
Added to this, the crises of the Catholic church (especially the controversy over the French Avignon Papacy and the Great Schism) along with the catastrophic effects of the Black Death were to lead to a re-evaluation of medieval values, resultant in the development of a humanist culture, stimulated by the works of Petrarch and Boccaccio. This prompted a revisitation and study of the classical antiquity, leading to the Renaissance. Florence benefited materially and culturally from this sea-change in social consciousness.
The extinction of the Medici line and the accession in 1737 of Francis Stephen, duke of Lorraine and husband of Maria Theresa of Austria, led to Tuscany's inclusion in the territories of the Austrian crown. Austrian rule was to end in defeat at the hands of France and the kingdom of Sardinia-Piedmont in 1859, and Tuscany became a province of the united kingdom of Italy in 1861.
Florence replaced Turin as Italy's capital in 1865, hosting the country's first parliament, but was superseded by Rome six years later following its addition to the kingdom.
After doubling during the 19th century, Florence's population tripled in the 20th with the growth of tourism, trade, financial services and industry. During World War II the city experienced a year-long German occupation (1943-1944). During the German retreat, Florence was declared an "open city" avoiding major war damage. The Allied soldiers who died driving the Germans from Tuscany are buried in cemeteries outside the city (Americans about 9 kilometers (6 miles) south of the city , British and Commonwealth soldiers a few kilometers east of the center on the north bank of the Arno )
On November 4 1966 the Arno flooded parts of the centre, killing at least 40 and damaging millions of art treasures and rare books. There was no warning from the authorities who knew the flood was coming, except a phone call to the jewellers on the Ponte Vecchio. Volunteers from around the world came to help rescue the books and art, and the effort inspired multiple new methods of art conservation. Forty years later, there are still works awaiting restoration.