pontifex maximus
the chief high priest of the College of Pontiffs in ancient Rome, open only to patricians until 254 BCE, when a plebeian first occupied this post; gradually became politicized until, beginning with Augustus, it was subsumed into the Imperial office
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Augustus as pontifex maximus (Via Labicana Augustus)
The pontifex maximus (Latin for 'supreme pontiff') was the chief high priest of the College of Pontiffs (Collegium Pontificum) in ancient Rome. This was the most important position in the ancient Roman religion, open only to patricians until 254 BC, when a plebeian first held this position. Although in fact the most powerful office in the Roman priesthood, the pontifex maximus was officially ranked fifth in the ranking of the highest Roman priests (Ordo Sacerdotum), behind the Rex Sacrorum and the flamines maiores (Flamen Dialis, Flamen Martialis, Flamen Quirinalis).