Ab urbe condita

"Ab Urbe condita" (related with Anno Urbis conditae: AUC or a.u.c.) is Latin for "from the founding of the City (Rome)", [Literally translated as "From the city having been founded".] traditionally set in 753 BC. It was used to identify the Roman year by a few Roman historians. Modern historians use it much more frequently than the Romans themselves did; the dominant method of identifying Roman years was to name the two consuls who held office that year. Before the advent of the modern critical edition of historical Roman works, AUC was indiscriminately added to them by earlier editors, making it appear more widely used than it actually was.Fact|date=July 2008 The regnal year of the emperor was also used to identify years, especially in the Byzantine Empire after Justinian required its use in 537. Examples of usage are principally found in German authors, for example Mommsen's "History of Rome".

ignificance

From Emperor Claudius onwards, Varro's calculation (see below) superseded other contemporary calculations. Celebrating the anniversary of the city became part of imperial propaganda. Claudius was the first to hold magnificent celebrations in honour of the city's anniversary, in 47, eight hundred years after the founding of the city. In 121, Hadrian, and in 147/8, Antoninus Pius held similar celebrations.

In 248, Philip the Arab celebrated Rome's first millennium, together with Ludi saeculares for Rome's alleged tenth saeculum. Coins from his reign commemorate the celebrations. A coin by a contender for the imperial throne, Pacatianus, explicitly states "Year 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 "Saeculum Novum".

When the Roman Empire turned Christian in the following century, this imagery came to be used in a more metaphysical sense.

Calculation by Varro

The traditional date for the founding of Rome of April 21, 753 BC, was initiated by Varro. Varro may have used the consular list with its mistakes, and called the year of the first consuls "245 "ab urbe condita", accepting the 244-year interval from Dionysius of Halicarnassus for the kings after the foundation of Rome. The correctness of Varro's calculation has not been proved scientifically but is still used worldwide.

Calculation by Dionysius Exiguus

The Anno Domini system was developed by a monk named Dionysius Exiguus in Rome in 525, as an outcome of his work on calculating the date of Easter. In his Easter table Dionysius equates the year AD 532 with the regnal year 248 of Emperor Diocletian. He invented a new system of numbering years to replace the Diocletian years that had been used in an old Easter table because he did not wish to continue the memory of a tyrant who persecuted Christians. At the beginning, his time calculation was limited on a small circle in Rome. It counted the years no longer after the accession of the emperor and Christian pursuer Diocletian ( 20 November 284), but starting from "incarnatione Domini", the birth of Christ. Exiguus is writing: "sed magis elegimus ab incarnatione Domini nostri Jesu Christi annorum tempora praenotare..." [Liber de Paschate, Migne Patrologia Latina  [http://books.google.com/books?vid=OCLC12663742&id=LcEYeL-4ZuEC&pg=PP10&lpg=PP10&dq=%22in+hoc+tomo+LXVII#PRA1-PT165,M1 67 page 481 note f] ] Because Dionysius Exiguus did not place the Incarnation in an explicit year, competent scholars have deduced both AD 1 and 1 BC. Later it was calculated by scholars that the year AD 1 corresponds to the Roman year DCCLIV ab urbe condita. Emperor Augustus was not called "Augustus", but "Imperator Caesar Divi filius" in the years 30 - 27 BC. This time could be forgotten by Exiguus. And a "year zero" does not exist in the Christian calendar:

...1 ab urbe condita = 753 before Christ

...2 ab urbe condita = 752 BC

...3 ab urbe condita = 751 BC ...

750 ab urbe condita = 4 BC (Death of Herod the Great)

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