The Certosa, a Carthusian monastery (or Charterhouse), was founded in September 1349 by Giovanni Visconti, ruler and archbishop of Milan: built well outside the city so that the monks could live and pray in silence and solitude, today it has been surrounded by the city's urban structure, but in spite of that, something of this atmosphere of peace can still be sensed here. Santa Maria Assunta in Certosa di Garegnano is considered to be one of the great monuments in the history of Ambrosian art and this is only one of the reasons why a visit to the Certosa is a worthwhile experience.