Milan Cathedral, or Metropolitan Cathedral-Basilica of the Nativity of Saint Mary, is the cathedral church of Milan, Lombardy, Italy. Dedicated to the Nativity of St. Mary, it is the seat of the Archbishop of Milan, currently Archbishop Mario Delpini.

A cathedral is a church that contains the cathedra of a bishop, thus serving as the central church of a diocese, conference, or episcopate. Churches with the function of "cathedral" are usually specific to those Christian denominations with an episcopal hierarchy, such as the Catholic, Eastern Orthodox, Anglican, and some Lutheran churches. Church buildings embodying the functions of a cathedral first appeared in Italy, Gaul, Spain, and North Africa in the 4th century, but cathedrals did not become universal within the Western Catholic Church until the 12th century, by which time they had developed architectural forms, institutional structures, and legal identities distinct from parish churches, monastic churches, and episcopal residences. The cathedral is more important in the hierarchy than the church because it is from the cathedral that the bishop governs the area under his or her administrative authority.