The archbishop of Milan wielded the greatest political influence of all state officials in Northern Italy in the 11th Century. Milan became a municipality in 1117 and managed to evade the authority of the archbishop. Later, it declared war on neighbouring municipalities and started to expand. The Lombard League was formed in reaction to Frederick I of Swabia’s attempt to capture the city. The League battled for the independence of Milan, but disintegrated after the defeat of Frederick Barbarossa in 1176.

Milan’s importance and influence began to rise in the 13th Century. The city walls were extended, roads were paved and new buildings sprung up. Milan’s official city status changed too, from a municipality to a seigneury. The aristocratic Visconti family, whose members hailed from Parma, Piacenza, Cremona, Brescia and Bergamo, came to power in 1300 and ushered in an era of opulence and prosperity. A large number of splendid monuments were built, including the Duomo, which was completed in 1386 and became the symbol of the city.

The Viscontis were succeeded by the Sforza dynasty, which brought peace to the city after many years of battling against Florence and Venice. Milan also became a centre of art and science, with Leonardo da Vinci and Donato Bramante working in the city.