Ab urbe condita
Ab urbe condita (Latin pronunciation: [ab ˈʊrbɛ ˈkɔndɪtaː]), or Anno urbis conditæ (Latin pronunciation: [ˈannoː ˈʊrbɪs ˈkɔndɪtae̯]), often abbreviated as AUC in either case, is a convention that was used in antiquity and by classical historians to refer to a given year in Ancient Rome. Ab urbe condita literally means "from the founding of the City", while anno urbis conditæ means "in the year since the City's founding". Therefore, the traditional year of the foundation of Rome, 753 BC, would be written AUC 1, while AD 1 would be AUC 754. The foundation of the Empire in 27 BC would be AUC 727.
Usage of the term was more common during the Renaissance, when editors sometimes added AUC to Roman manuscripts they published, giving the false impression that the convention was commonly used in antiquity. In reality, the dominant method of identifying years in Roman times was to name the two consuls who held office that year. In late antiquity, regnal years were also in use, as was the Diocletian era in Roman Egypt after AD 293, and in the Byzantine Empire after AD 537, following a decree by Justinian.
The traditional date for the founding of Rome, 21 April 753 BC, is due to Marcus Terentius Varro (First Century BC). Varro may have used the consular list (with its mistakes) and called the year of the first consuls "ab urbe condita 245," accepting the 244-year interval from Dionysius of Halicarnassus for the kings after the foundation of Rome. The correctness of this calculation has not been confirmed, but it is still used worldwide.
From the time of Claudius (ruled AD 41 to AD 54) onward, this calculation superseded other contemporary calculations. Celebrating the anniversary of the city became part of imperial propaganda. Claudius was the first to hold magnificent celebrations in honor of the anniversary of the city, in AD 48, the eight hundredth year from the founding of the city. Hadrian and Antoninus Pius held similar celebrations, in AD 121, and in AD 147 and AD 148, respectively.
In AD 248, Philip the Arab celebrated Rome's first millennium, together with Ludi saeculares for Rome's alleged tenth sæculum. Coins from his reign commemorate the celebrations. A coin by a contender for the imperial throne, Pacatianus, explicitly states "[y]ear one thousand and first", which is an indication that the citizens of the empire had a sense of the beginning of a new era, a Sæculum Novum.
The Anno Domini (AD) year numbering was developed by a monk named Dionysius Exiguus in Rome in AD 525, as a result of his work on calculating the date of Easter. Dionysius did not use the AUC convention, but instead based his calculations on the Diocletian era. This convention had been in use since AD 293, the year of the tetrarchy, as it became impractical to use regnal years of the current emperor. In his Easter table, the year AD 532 was equated with the 248th regnal year of Diocletian. The table counted the years starting from the presumed birth of Christ, rather than the accession of the emperor Diocletian on 20 November AD 284, or as stated by Dionysius: "sed magis elegimus ab incarnatione Domini nostri Jesu Christi annorum tempora praenotare" ("but rather we choose to name the times of the years from the incarnation of our Lord Jesus Christ"). Blackburn and Holford-Strevens review interpretations of Dionysius which place the Incarnation in 2 BC, 1 BC, or AD 1.
- J. David Thomas, "On Dating by Regnal Years of Diocletian, Maximian and the Caesars", Chronique d'Egypte 46.91 (1971), 173–179, doi:10.1484/J.CDE.2.308234.
- Liber de Paschate, Migne, Patrologia Latina, Volume 67, page 481, note f
- Blackburn, B. & Holford-Strevens, L, The Oxford Companion to the Year (Oxford University Press, 2003 corrected reprinting, originally 1999) 778–780.