The Pontifical Equestrian Order of St. Gregory the Great (Latin: Ordo Sancti Gregorii Magni, Italian: Ordine di San Gregorio Magno) was established on 1 September 1831, by Pope Gregory XVI, seven months after his election to that seat by the College of Cardinals.The Order of St. Gregory the Great is one of the five Orders of Knighthood of the Holy See.