The festival of Santa Fina, who died in 1253 and who has long been venerated as the patron saint of San Gimignano, reaches its high point of celebration with Mass in the Basilica di Santa Maria Assunta and with a fair in the Piazza del Duomo and Piazza della Cisterna, all assisted by the local council. Born in 1238 to two déclassés nobles of San Gimignano, Iosefina (Fina) died in 1253 at the age of fifteen. An illness that struck her at the age of ten left her paralysed, and her suffering was only increased by the death of her mother. For those who came to visit her, she was an example of Christian life. When she died, according to her Dominican biographer Giovanni del Coppo, the bells of the city rang without anyone ringing them. Her following spread rapidly, not least due to the many miracles that took place around her tomb. Declared patron saint of the Tuscan town, a hospital was built in her honour, and in 1457 the Consiglio del Popolo commissioned a magnificent chapel in the Collegiate. 

Source: sangimignano.com