Rito della Nivola
The Rite of the Nivola (in Italian Rito della Nivola) is a Catholic liturgical rite (part of the Ambrosian Rite) as well as a historical reenactment that is celebrated yearly in the Duomo (Cathedral) of Milan, Italy; the tradition dates back to the 16th century and was initiated by Carlo Borromeo. It is a celebration of the "Santo Chiodo" (Holy Nail), purportedly a nail from the True Cross, which is regarded as the most important relic owned by the Archdiocese of Milan.