Montevarchi's own feast is that of its patron Saint Lawrence, on 10 August, celebrated in the Collegiate Church of San Lorenzo.
The same collegiate church holds the relic of the Holy Milk of the Virgin Mary, once the centre of the far older Festa del Sacro Latte, the keystone of the power structure of the Fraternita del Sacro Latte. When the confraternity was suppressed and dismantled at the end of the 18th century, the feast changed its name to Festa del Perdono, drawing on a more general Catholic tradition and aligning, in name, with those of nearby towns, especially San Giovanni Valdarno and Terranuova Bracciolini: it is still held today every first Sunday of September, followed the next Monday by a fair.
