 Construction began in 1589, around an existing sanctuary dedicated to the Virgin Mary whose creation is traditionally attributed to Saint Eusebius of Vercelli, around 350 AD.Eusebius is also said to have installed the statue of the Madonna which is still venerated in the sanctuary.The chapels dedicated to the Mysteries of the Rosary were positioned around the one-thousand-year-old Marian sanctuary on the highest of the hills of Basso Monferrato .