galero

A galero (pl. galeri; L. galerum, pl. galera) in the Roman Catholic Church is a large, broad-brimmed tasseled hat worn by clergy. Over the centuries the galero was eventually limited in use to individual cardinals as a crown symbolizing the title of Prince of the Church. The red galero was first granted to cardinals by Pope Innocent IV in 1245 at the First Council of Lyon. Tradition in the Archdiocese of Lyon is that the red color was inspired by the red hats of the canons of Lyon. According to Noonan, Pope Innocent wanted his favorites to be distinct and recognizable in the lengthy processions at the council.
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