th, in what is now the Camollia district. Walls were built to totally surround the city, and a second set was finished by the end of the 13th century. Much of these walls still exist today.
Siena's university, founded in 1240 and famed for its faculties of law and medicine, is still among the most important Italian universities. Siena rivalled Florence in the arts throughout the 13th and 14th centuries: the important late medieval painter Duccio (1253–1319) was a Sienese, but worked across the peninsula, and the mural of "Good Government" by Ambrogio Lorenzetti in the Palazzo Pubblico, or town hall, is a magnificent example of late-Medieval/early Renaissance art as well as a representation of the utopia of urban society as conceived during that period. Siena was devastated by the Black Death of 1348, and also suffered from ill-fated financial enterprises. In 1355, with the arrival of Charles IV of Luxembourg in the city, the population rose and suppressed the government of the Nove (Nine), establishing that Dodici (Twelve) nobles assisted by a council with a popular majority. This was also short-lived, being replaced by the Quindici (Fifteen) reformers in 1385, the Dieci (Ten, 1386–1387), Undici (Eleven, 1388–1398) and Twelve Priors (1398–1399) who, in the end, gave the city's seigniory to Gian Galeazzo Visconti of Milan in order to defend it from the Florentine expansionism.
In 1404 the Visconti were expelled and a government of Ten Priors established, in alliance with Florence against King Ladislaus of Naples. With the election of the Sienese Pius II as Pope, the Piccolomini and other noble families were allowed to return to the government, but after his death the control returned into popular hands. In 1472 the Republic founded the Monte dei Paschi, a bank that is still active today and is the oldest surviving bank in the world. The noble factions returned in the city under Pandolfo Petrucci in 1487, with the support of Florence and of
