San Marco is a church in Milan, northern Italy. According to tradition, the church was dedicated to St. Mark, patron of Venice, after the help given by that city in the war against Frederick Barbarossa in the 12th century. However, the first mention of the church dates from 1254 when the Augustinians built a Gothic style edifice with a nave and two aisles r…San Marco is a church in Milan, northern Italy. According to tradition, the church was dedicated to St. Mark, patron of Venice, after the help given by that city in the war against Frederick Barbarossa in the 12th century. However, the first mention of the church dates from 1254 when the Augustinians built a Gothic style edifice with a nave and two aisles re-using pre-existing constructions. The area of present Via San Marco contained a basin called Laghetto di San Marco which connected to various canals ; the basin was filled in the 1930s, and the area now sports a frequent outdoor market.