They were a family of incredibly rich and powerful art patrons. one of them also became Pope.

Ghibellines and Guelfs. Italian names were given to two German political parties that kept Italy and Germany in a state of turmoil during the Middle Ages. Their rivalry involved cities, rulers, and popes. Guelfo, one of the names, is Italian for “Welf,” the name of a ducal family that ruled Bavaria and Saxony in the Middle Ages. Guelphs typically came from wealthy mercantile families, while the Ghibellines' prosperity came from landed estates, achieved through business wiles, might and coercion. The terms church party and imperial party, respectively, are preferred in some parts of the country today. Guelfs and Ghibellines Italian political terms derived from the German Welf, a personal and thence family name of the dukes of Bavaria, and Waiblingen, the name of a castle of the Hohenstaufen dukes of Swabia apparently used as a battle cry. Presumably introduced into Italy 1198-1218. Factional struggles had existed within the Italian states from time immemorial, the parties taking a multitude of local names. In Florence, however, Guelf and Ghibelline were applied to the local factions which supposedly originated in a feud between the Buondelmonte and Amidei clans, c. 1216. In 1266-67 the Guelf party, which had recruited most of the merchant class, finally prevailed over the predominantly noble Ghibellines; after this, internal factions in Florence went under other names, like the Blacks and the Whites who contested for control of the commune between 1295 and 1302. Medicis Cosimo de Medici, was a Florentine merchant banker. The Medici family served as the world-wide tithe and tax collector for the Catholic Church. Italian noble family that produced three popes (Leo X, Clement VII, and Leo XI) and two queens of France (Catherine de Médicis and Marie de Médicis). Cosimo "the Elder" (1389-1464) was the first of the family to rule Florence. Lorenzo "the Magnificent" (1449-1492) was an outstanding patron of learning and the arts, whose clients included Michelangelo and Botticelli. Medici rule begins with Cosimo il Vecchio ("Cosmio the Old") In 1494 the Medicis went broke and lost their hold on power. The city fell under the control of Girolamo Savonarola, a Dominican monk who led a puritanical republic until he fell from public favour and was burned as a heretic in 1498. The Medicis returned to Florence in the 16th century, having united themselves by marriage with Emperor Charles V, and ruled for the next 200 years. http://www.britannica.com/ebi/article-9274687 http://www.italy.worldweb.com/FeaturesReviews/TownCityReviews/8-145159.html http://www.photo.net/italy/florence-history http://www.thingstodo-florence.com/brochure/content.jsp?FIELD=History