, to the left extends the former laghetto 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 (artificial lake) called
Laghetto di San Marco which connected to various canals (navigli); the basin was filled in the 1930s, and the area now sports a frequent outdoor market. The structure was heavily modified in the
Baroque style during the 17th century, when it became the largest church in the city after the
Duomo di Milano. In early 1770, the young
Mozart resided in the monastery of San Marco for three months and, on May 22, 1874, the first anniversary of the death of the Milanese poet and novelist
Alessandro Manzoni was commemorated in the church by the first performance of
Verdi's
Requiem, written in his honour. Organists at the church have included
Ruggier Trofeo. ==Art and architecture==