This small church lies south of the city in an area still surrounded by fields, a treasure trove of artistic beauty. The building is a wealth of artistic documentations that illustrate developments in the Lombardian culture from the 16th to the 19th century and it still conserves an organ that has been restored to its original ancient splendour.The name of the church is a reference to the ronchetti which are the fields reclaimed from the surrounding woodlands. It is around these ronchetti that the population reunited, around an original religious nucleus made up of the oratories of St. Pietro and St. Materno.With the arrival of the Barbarians, in particular following the devastation of Milan by the Huns of Attila, this area had an increase in population who had fled from the city and who gathered in this area as it offered fields to cultivate.From an ancient document we are able to detect the presence of the church of Saints Pietro and Paolo around 1300 when, at the end of the Barbaric invasions, Milan had gradually regained autonomy and dominated in Lombardy under the rule of the Torriani and, successively, the Visconti family; the latter became owners of a large amount of terrain just outside the city walls, in what was the middle Ronchetto or Ronchettino, later called visconteo which, united to the lower and upper Ronchetti, made up the Tre Ronchetti.According to the testimony of the deacon Paolino the area of the ronchetti was already known to Saint Ambrogio, patron of the city, who had roamed the Milanese outskirts to escape from the approaching Episcopal election, trying vainly to reach Ticinium or Pavia.On the 9th of April 1567 the church received a visit from Saint Carlo Borromeo, an ecclesial event that, a few months later, led to the construction of the Tre Ronchetti parish.