Ab urbe condita (Latin: [ab ˈʊrbɛ ˈkɔndɪtaː] 'from the founding of the City'), or anno urbis conditae (Latin: [ˈan.no̯‿ˈʊrbɪs ˈkɔndɪtae̯]; 'in the year since the city's founding'), abbreviated as AUC or AVC, expresses a date in years since 753 BC, the traditional founding of Rome. It 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, the year 1 BC would be written AUC 753, whereas AD 1 would be AUC 754. The foundation of the Roman Empire in 27 BC would be AUC 727. The current year AD 2023 would be AUC 2776.

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.