Roman Catholic Archdiocese of Cologne Tags: Clerical Administrative Region, Diocese.The Archdiocese of Cologne (Latin: Archidioecesis Coloniensis; German: Erzbistum Köln) is an archdiocese of the Catholic Church in western North Rhine-Westphalia and northern Rhineland-Palatinate in Germany. thumbnail area (km2) 6.181e+09 country Germany Established 2nd Century jurisdiction Diocese patron Immaculate Conception, Saint Joseph province Cologne Learn more... Loading...