Celtic tribe belonging to the Insubres group 590–222 BC
Roman Republic 222–27 BC
Roman Empire 27 BC–AD 395
Western Roman Empire 395–476
Kingdom of Italy 476–493
Ostrogothic Kingdom 493–553
Eastern Roman Empire 553–569
Lombard Kingdom 569–774
Carolingian Empire 774–781
Regnum Italiae 781–1014
Holy Roman Empire 1014–1114
Free Commune 1114–1259
Lordship of Milan 1259–1395
Duchy of Milan 1395–1447
Golden Ambrosian Republic 1447–1450
Duchy of Milan 1450–1796
Transpadane Republic 1796-1797
Cisalpine Republic 1797–1802
Italian Republic 1802–1805
Kingdom of Italy 1805–1814
Kingdom of Lombardy–Venetia 1815–1859
Kingdom of Sardinia 1859–1861
Kingdom of Italy 1861–1943
Italian Social Republic 1943–1945
Kingdom of Italy 1945–1946
Italian Republic 1946–present

Milan is an ancient city in northern Italy first settled under the name Medhelanon in about 590 BC by a Celtic tribe belonging to the Insubres group and belonging to the Golasecca culture. It was conquered by the ancient Romans in 222 BC, who latinized the name of the city into Mediolanum. The city's role as a major political centre dates back to the late antiquity, when it served as the capital of the Western Roman Empire.

From the 12th century until the 16th century, Milan was one of the largest European cities and a major trade and commercial centre, as the capital of the Duchy of Milan, one of the greatest political, artistic and fashion forces in the Renaissance. Having become one of the main centres of the Italian Enlightenment during the early modern period, it then became one of the most active centres during the Restoration, until its entry into the unified Kingdom of Italy. From the 20th century onwards Milan became the industrial and financial capital of Italy, one of the economic capitals of Europe and a global financial centre.

Milan was founded with the Celtic name of Medhelanon, later latinized by the ancient Romans into Mediolanum. In Celtic language medhe- meant "middle, centre" and the name element -lanon is the Celtic equivalent of Latin -planum "plain", meant "(settlement) in the midst of the plain", or of "place between watercourses" (Celtic medhe = "in the middle, central"; land or lan = "land"), given the presence of the Olona, Lambro, Seveso rivers and the Nirone and Pudiga streams.

The dh sound, which has disappeared from the modern Milanese dialect, was instead present in the ancient local idiom once spoken in Milan. It is found, among others, as well as in Medhelanon, in the ancient Milanese words doradha ("golden"), crudho ("abrupt person"), mudha ("change") and ornadha ("ornate"). In Milanese dialect, the oldest name of which documented traces have been found is Miran.

The Latin name Mediolanum comes from the Latin words medio (in the middle) and planus (plain). However, some scholars believe that lanum comes from the Celtic root lan, meaning an enclosure or demarcated territory (source of the Welsh word llan, meaning "a sanctuary or church", ultimately cognate to English/German Land) in which Celtic communities used to build shrines.

Hence Mediolanum could signify the central town or sanctuary of a Celtic tribe. Indeed, about sixty Gallo-Roman sites in France bore the name "Mediolanum", for example: Saintes (Mediolanum Santonum) and Évreux (Mediolanum Aulercorum). In addition, another theory links the name to the scrofa semilanuta ("half-woolly sow") an ancient emblem of the city, fancifully accounted for in Andrea Alciato's Emblemata (1584), beneath a woodcut of the first raising of the city walls, where a boar is seen lifted from the excavation, and the etymology of Mediolanum given as "half-wool", explained in Latin and in French.

According to this theory, the foundation of Milan is credited to two Celtic peoples, the Bituriges and the Aedui, having as their emblems a ram and a boar; therefore "The city's symbol is a wool-bearing boar, an animal of double form, here with sharp bristles, there with sleek wool." Alciato credits Ambrose for his account.