For John Bosco, the Cathedral was his favourite among the many churches in the city. Here, while still a student, he came every morning and every evening to pray at the Lady of Grace and, again within these walls, he prepared the sacristan Carlo Palazzolo for the Latin course, because he wanted to become a priest. During his years in the seminary, he continued to visit the Cathedral for functions and for the catechism for children, while at the altar of Our Lady of the Grace, on 9 June 1841, already Don Bosco, he was to hold his fourth mass.