The Certosa, a Carthusian monastery or Charterhouse, was founded in 19 September 1349 by Giovanni Visconti, ruler and archbishop of Milan. It was built well outside the city so that the monks could live and pray in silence and solitude. Today it has been enveloped by the city's urban structure, but something of this atmosphere of peace can still be sensed here. This is one of the reasons why a visit to the Certosa is a worthwhile experience.
The building was consecrated in 1367, and it is dedicated to Saint Mary. The building has a single nave, with a barrel vault, without a transept. Originally the Certosa was near the postal road running from Milan to Varese and Gallarate, and it was immersed in the forest named Bosco della Merlata, an area populated by brigands and thieves. The monastery therefore represented a safe refuge for pilgrims and travellers.
Santa Maria Assunta in Certosa di Garegnano is considered to be one of the great monuments in the history of Ambrosian art. When it was built the area was called Garegnano Marcido, a hamlet of Musocco. The name “Marcido” derives from “marcite”, which refers to the water-meadow system of cultivation typical in the Lombard plains and utilized by the monks of the Certosa.
The complex includes works of considerable artistic interest. Simone Peterzano (the famous Caravaggio was his pupil) painted a cycle of paintings in two successive periods, including the Crucifixion in the apse. Daniele Crespi also painted works here, because he was forced to live in the monastery for several years, in hiding from the police who were seeking him in connection with a murder. He returned the monks' hospitality by painting the entire vault of the central nave. The vault of the capitular hall has a fine fresco depicting Saint Michael, by Bernardo Zenale (early 16th century).
The church façade is also of interest, dating to the late 16th-early 17th centuries and attributed to Galeazzo Alessi and Vincenzo Seregni. It is divided into three symmetrical orders, cadenced on the two lower levels by pairs of granite pilasters, with capitals in yellow Angera stone.
In the lower order, there is a single portal, along with two granite columns, and a high-relief in Candoglia marble depicting the repose of the Holy Family during the flight into Egypt. At the centre of the middle order there is a window with a balcony in red Angera stone, with a statue of Saint Carlo Borromeo on the right, and another of Saint Ambrose on the left, also in Candoglia marble.
In the upper order there is a bas-relief depicting Mary Magdalene.
The façade also includes a statue of the Virgin Mary between two angels.The Certosa once included a Priory and Great Cloister surrounded by the monks' cells, similar to the structures that can still be seen today at the Certosa di Pavia. In 1783, the coenobium was suppressed and the Carthusian monks were expelled. The convent was then partially demolished and in part used for housing.
The reputation of splendour and sanctity that surrounded the monastic community was in part due to Petrarch, who visited this monastery several times. After he had seen the Grande Chartreuse, he wrote: "So, I have been in Paradise: I have seen the Angels of God on earth; I have seen living in bodies here on earth those whose home will be the Heavens." According to tradition, Petrarch visited the Certosa every week, and was granted unrestricted access to the monastery.The complex was restored in 1930 by Ambrogio Annoni. The latest restoration took place in 1982.