The Cathedral has a prominent role in determining the beginning of the Pisan New Year. Between the tenth century and 1749, when the Tuscan calendar was reformed, Pisa used its own calendar, in which the first day of the year was March 25, the feast day of the Annunciation of Mary. Years were counted such that the Pisan New Year begins 9 months before the ordinary one. The exact moment is determined by a ray of sun that, through a window on the left side, falls on an egg-shaped marble, just above the pulpit by Giovanni Pisano; this occurs at noon.