According to the legend of Judas Cyriacus, the 3 May is the day that the relic of the True Cross was found; and in deference to this tradition, Lucca and its archdiocese take this day to celebrate the Finding of the True Cross. The rites are centred around the Cathedral, beginning with the dressing of the Volto Santo at dawn and continuing with a full day of Holy Masses. The festival finishes with an animal fair in the Foro Boario and with another market set up in the piazza around the Duomo (Piazza San Martino, Piazza Antelminelli, Piazza San Giovanni).
Source: Belli Barsali I., Guida di Lucca, Maria Pacini Fazzi Editore, Lucca, 1970.