Catholic Day celebration of Missa Papae Marcelli, or Pope Marcellus Mass, a mass by Giovanni Pierluigi da Palestrina, attended by 50,000 people during the California Pacific International Exposition held May - November 1935 and February - September 1936. Over 14 Clergymen joined approximately 1,400 uniformed members of 210 Holy Name Societies and 50 other societies in a processional and recessional. The mass was composed in honor of Pope Marcellus II, who reigned for three weeks in 1555.