The Quindecemviri Sacris Faciundis (XVVIRI S. F. in inscriptions) was a very important priesthood in Ancient Rome. Translated as the ‘board of fifteen for the performance of sacred rites’ (short and to the point as always…), the college was one of the four great priestly colleges. Dionysius of Halicarnassus (Dion. 4.62) claims that the college consisted of two members under the last king Tarquinius (535-509 BCE), referred to as the duumviri sacrorum. This number rose to ten in the early-Republic (decemviri sacris faciundis), and then again to fifteen in the late-Republic (quindecemviri sacris faciundis). The body also annually elected two ‘heads’ of the college.

Throughout much of Roman History, the quindecemviri had a number of religious roles, but their main duty was to care for and interpret the ‘Sibylline books’: a collection of oracular utterances which were consulted for prophecies in times of crisis. It was based upon a reading of these books that the quindecemvir Lucius Cotta supposedly prophesised that Parthia could only be conquered by a king (Suet. Jul. 79). A prophesy that would prove fatal for a certain Gaius Julius Caesar…

During the reign of the Julio-Claudian dynasty (the first five emperors who ruled from 27 BCE – 68 CE, fig. 1), Rome underwent a range of societal changes. Society transformed as the Empire transitioned from semi-democratic republic to a monarchy. Necessitated by this transition, the religion of Ancient Rome underwent as series of changes as well. Understanding the quindecemviri during this period is therefore of great significance. Who were the men in this powerful religious college? What was their role? What was their relationship with the emperors?

Who were they?

By 17 BCE, as recorded in an inscription recounting Augustus’ ludi saeculares (an important festival supposedly celebrated every 100-110 years), the so-called ‘board of fifteen’ was more like the ‘board of twenty-one’ (Acta ludorum saecularium, fig. 2). In fact, while the Acta lists 21 members, scholars such as Martha Hoffman (1953) have noted that there may have been more, with some members omitted because they were not present in Rome at the time. The quindecemviri was probably bolstered to this large size when Augustus enlarged other colleges in 30 BCE (Dio Cass. 51.20). Despite all of this, the body retained the name quindecemviri sacris faciundis.

The men who constituted this now enlarged body were evidently some of the most illustrious men of their day, men who had typically seen very successful political, military and religious careers. Illustrating this point, a recent study of 59 inscriptions dating to the Julio-Claudian period conducted by the Interpreters of the Sibyl Project found that of the 47 named quindecemviri, only 3 had never been consul or consul suffect, the most important magisterial positions in Rome (fig. 3).

To illuminate this point further, several quindecemviri were members of the Julio-Claudian Emperors’ inner circles. Cossus Cornelius Lentulus Gaeticliucs, a quindecemvir under Augustus and Tiberius (23 BCE – 37 CE), was a personal drinking companion of Tiberius. The historian Seneca (Sen. Epp. 83.15) even records that it was during one of their many drinking sessions that Cornelius was promoted to Urban Prefect (an important magisterial position). Several Julio-Claudian Emperors and members from the imperial household were themselves also members of the priesthood. In the aforementioned Acta ludorum saecularium Augustus and his close companion Marcus Agrippa are recorded as the two heads of the college, and were charged with the curation of the Ludi Saeculares (17 BCE). The emperors possibly wanted membership within the priesthood in order to have (even) more of a say in important religious matters. Indeed, it is Tiberius (14-37 CE) who rejects Gaius Asinius Gallus’ proposition to consult the Sibylline books about the flooding of the Tiber (Tac. Ann. 1.76).

Many of the Julio-Claudian quindecemviri also held a range of socio-political, military and religious posts before and after their admission into the priesthood. Lucius Caninius Gallus, for example, was one of the three triumvir monetalis (board of moneyers) in 12 BCE, minting a number of issues (found here), such as RIC I2 416 (fig. 4). While probably not a quindecemvir in 12 BCE, he definitely was by 1-10 CE when he became Proconsul (Governor) of the province of Africa, for the religious office is recorded on an inscription from Leptis Magna (IRT 521). In 15 CE Caninius is also made one of the five curatores riparum et alvei Tiber (curators of the banks and channel of the Tiber river). Interestingly, the engineer Frontius records another quindecemvir, Aulus Didius Gallus, serving in a similar body in the 40s CE (Front. Aq. 2.102). Instead of looking after the Tiber, Didius was a curatores aquarum, or ‘curator of the aqueducts’, thus overseeing the maintenance of the Rome’s ever important water sources.

While today in modern Australia we would have an issue with a federal minister concurrently being an active general, state premier, and religious leader, the Romans evidently would not.

Roles of the Quindecemviri under the Julio-Claudians

Now we know who they were, it is time to explore what they actually did. As outlined earlier, the primary role of the quindecemviri was to care for and interpret the Sibylline books, and the Julio-Claudian quindecemviri were no different. As mentioned, Gaius Asinius Gallus proposed to consult the Sibylline books during the reign of Tiberius, and was rejected by the Emperor (Tac. Ann. 1.76). What is important to note is that this proposition was made in the senate, and to the emperor Tiberius, indicating that that this may have been required of the Julio-Claudian quindecemviri. A certain Lucius Caninus Galllus is indeed recorded to have made a proposition to edit the Sibylline books to the senate and Tiberius, and on this occasion the quindecemvir was more successful, being told to discuss the matter with his fellow quindecemviri (Tac. Ann. 6.12).

In addition to this primary function, the priesthood also had two other more general roles: to organise certain games and festivals, and to conduct or oversee public sacrifices. Typically, these happened in unison. As previously noted, the quindecemviri of 17 BCE oversaw the ludi saeculares and conducted a number of sacrifices during the event. An inscription from Campania (Italy) referred to as the Fasti Praenestini (fig. 5) also records that, after Augustus’ calendar reforms of 8 CE, the quindecemviri and the other great priestly colleges “[annually] sacrificed victims to the godhead of Augustus at the altar” on the 17th of January.

The quindecemviri may also have conducted sacrifices outside of festival contexts. Dio Cassius records the quindecemvir Potitus Valerius Messalla conducting a public sacrifice in Rome to celebrate Augustus’ triumphal return from Pharsalus in 29 BCE (Dio 51.21). However, Valerius was also a consul suffect in this year, and it is difficult to discern in what capacity he is conducting this sacrifice. A similar issue is seen with the evidence from Leptis Magna (fig. 6) in relation to building dedications (a ritual which typically involved a sacrifice). Epigraphic evidence attests to a certain Quintus Marcius Barea overseeing two dedicatory sacrifices between 41-43 CE in Leptis Magna (IRT 273; CIL 08 6987), but Marcius was also governor of Africa during this time, so we are left with the same issue. Nonetheless, this could be evidence of the quindecemviri exercising their powers overseas.


The quindecemviri sacris faciundis was evidently an important priesthood in Julio-Claudian Rome, comprising of numerous illustrious individuals who often held a number of important positions concurrently with their priesthood, or prior to their admission. Moreover, the prolific nature of their careers leads to issues of ambiguity within the evidence concerning the priesthood’s roles. Roles which, in summary, were to care for and interpret the Sibylline books, and to organise, conduct, and oversee religious events and public sacrifices.

Ewan Coopey

Ewan is a Research Assistant and HDR student studying Roman Dalmatia. His passion for all things ancient and medieval arose in childhood when he would wander through the Roman forts and medieval castles which are scattered across the British Isles. His research interests include: provincial archaeology, the Roman military, identity in the ancient world, and the province of Dalmatia.