ngobarda" near the complex of S. Stefano. Charlemagne stayed in this district in 786. In the 11th century, under the Holy Roman Empire, Bologna began to aspire to being a free commune, which it was able to do when Matilda of Tuscany died, in 1115, and the following year the city obtained many jud

Porta Maggiore, one of the twelve medieval city gates of Bologna.


Depiction of a 14th-century fight between the militias of the Guelf and Ghibelline factions in Bologna, from the Croniche of Giovanni Sercambi of Lucca.
After a long decline, Bologna was reborn in the 5th century under Bishop Petronius. According to legend, St. Petronius built the church of S. Stefano. After the fall of Rome, Bologna was a frontier stronghold of the Exarchate of Ravenna in the Po plain, and was defended by a line of walls which did not enclose most of the ancient ruined Roman city. In 728, the city was captured by the Lombard king Liutprand, becoming part of the Lombard Kingdom. The Germanic conquerors formed a district called "addizione longobarda" near the complex of S. Stefano. Charlemagne stayed in this district in 786.
In the 11th century, under the Holy Roman Empire, Bologna began to aspire to being a free commune, which it was able to do when Matilda of Tuscany died, in 1115, and the following year the city obtained many judicial and economic concessions from Emperor Henry V. Bologna joined the Lombard League against Frederick Barbarossa in 1164 which ended with the Peace of Constance in 1183; after which, the city began to expand rapidly (this is the period in which its famous towers were built) and it became one of the main commercial trade centres thanks to a system of canals that allowed large ships to come and go.
Traditionally said to be founded in 1088, the University of Bologna is widely considered to be the first university.[5][6] The university originated as an international centre of study of medieval Roman law under major glossators, including Irnerius. It numbered Dante, Boccaccio and Petrarca among its students.[7]
In the 12th century, the expanding city needed a new line of walls, and at the end of the 13th century, Bologna had between 50,000 and 60,000 inhabitants making it the fifth largest city in Europe (after Cordova, Paris, Venice, and Florence) and tied with Milan as the largest textile industry area in Italy. The complex system of canals in Bologna was one of the most advanced waterway systems in Europe, and took its water from the Savena, Aposa and Reno Rivers. The main canals were Canale Navile, Canale di Reno and Canale di Savena. Hydraulic energy derived from the canal system helped run the numerous textile mills and transport goods.[8]
In 1256, Bologna promulgated the "Paradise Law", which abolished feudal serfdom and freed the slaves, using public money. At that time the city centre was full of towers (perhaps 180), built by the leading families, notable public edifices, churches, and abbeys. In the 1270s Bologna's politics was dominated by Luchetto Gattilusio, a Genoese diplomat and man of letters who became the city Governor. Like most Italian cities of that age, Bologna was torn by internal struggles related to the Guelph and Ghibelline factions, which led to the expulsion of the Ghibelline family of the Lambertazzi in 1274.