Antoninianus of Pacatianus, usurper of Roman emperor Philip in 248. It reads ROMAE AETER[NAE] AN[NO] MIL[LESIMO] ET PRIMO, 'To eternal Rome, in its one thousand and first year.'

Ab urbe condita (Latin: [ab ˈʊrbɛ ˈkɔndɪtaː]; 'from the founding of the City'), or Anno urbis conditae (Latin: [ˈan.n^o̯‿ʊrbɪs ˈkɔndɪtae̯]; 'in the year since the City's founding'),^{[note 1]} often abbreviated as AUC, is an expression used in antiquity and by classical historians to refer to a given year in Ancient Rome. In reference to the traditional year of the foundation of Rome, 753 BC would be written AUC 1, whereas AD 1 would be AUC 754. The foundation of the Roman 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 in Roman Egypt during the Diocletian era after AD 293, and in the Byzantine Empire from AD 537, following a decree by Justinian.

Significance

The traditional date for the founding of Rome, 21 April 753 BC, is due to Marcus Terentius Varro (1st 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 (fl. AD 41 to AD 54) onward, this calculation superseded other contemporary calculations.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.^{[citation needed]} Hadrian, in AD 121, and Antoninus Pius, in AD 147 and AD

Ab urbe condita (Latin: [ab ˈʊrbɛ ˈkɔndɪtaː]; 'from the founding of the City'), or Anno urbis conditae (Latin: [ˈan.n^o̯‿ʊrbɪs ˈkɔndɪtae̯]; 'in the year since the City's founding'),^{[note 1]} often abbreviated as AUC, is an expression used in antiquity and by classical historians to refer to a given year in Ancient Rome. In reference to the traditional year of the foundation of Rome, 753 BC would be written AUC 1, whereas AD 1 would be AUC 754. The foundation of the Roman 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 in Roman Egypt during the Diocletian era after AD 293, and in the Byzantine Empire from AD 537, following a decree by Justinian.