The city proper has a population of about 1.35 million, while its urban area is the 5th largest in the EU and the largest in Italy with an estimated population of about 5.2 million. The massive suburban sprawl that followed the post-war boom of the 1950s–60s and the growth of a vast commuter belt, suggest that socioeconomic linkages have expanded well beyond the boundaries of its administrative limits and its agglomeration, creating a metropolitan region of 7 to 9 million people. According to Eurostat the Milan metropolitan region contains a population of 8,071,271 people in 2011. It has been suggested that the Milan metropolitan region is part of the so-called Blue Banana, the area of Europe with the highest population and industrial density.
Milan was founded by the Insubres, a Celtic people. The city was later conquered by the Romans, becoming the capital of the Western Roman Empire. During the Middle Ages, Milan flourished as a commercial and banking center. In the course of centuries, it has been alternatively dominated by France, Habsburg Spain, and Austria, until when in 1859 the city was eventually annexed by the new Kingdom of Italy. During the early 1900s, Milan led the industrialization process of the young nation, being at the very center of the economic, social and political debate. Badly affected by the World War II devastations, and after a harsh Nazi occupation, the city became the main centre of the Italian Resistance. In post-war years, the city enjoyed a prolonged economic boom, attracting large flows of immigrants from rural Southern Italy. During the last decades, Milan has seen a dramatic rise in the number of international migrants, and today more than one sixth of its population is foreign born.