He studied at Paris and Bologna, and, having been successively archpriest of St Peter's, papal chaplain, cardinal-deacon of Sant' Eustachio, cardinal-bishop of Ostia, the first protector of the Franciscan order, and papal legate in Germany under Innocent III., and Honorius III., he succeeded the latter in the papacy.
The Patriarchate of Alexandria, consisting of Egypt and its dependencies, was at one time the most powerful, as it was the most centralized, of all, and the patriarch still preserves his ancient titles of " pope " and " father of fathers, pastor of pastors, archpriest of archpriests, thirteenth apostle, and oecumenical judge."
Out of these developed the rural deaneries, the office of archpriest being ultimately merged in that of rural dean, with which it became synonymous.
In Rome itself, as the office of archdeacon grew into that of cardinal-camerlengo, so that of archpriest of St Peter's developed into that of the cardinal-vicar.
In England from 1598 until the appointment of a vicar-apostolic in 1623 the Roman Catholic clergy were placed by the pope under an "archpriest" as superior of the English mission.