This nickname dates from ancient times, when the year in Pisa's religious calendar began on March 25 (the day of the Annunciation), rather than nine months later, as in the Gregorian calendar on Christmas Day. March 25 falls in the month of Aries, and the arrangement of all the buildings in Piazza dei Miracoli (Cathedral, Baptistery, and Campanile) resembles the constellation of Aries in shape.
