No one claims that Rome was founded in 753 or 754 BCE. When modern historians or classicists refer to that date, they usually add that it is legendary. But that’s a bit too kind. It is not just one of Rome’s legendary foundation dates, it is also the only date about which we know why it is incorrect.
The study of ancient chronology is a technical subject, but the conclusions can be interesting, so let’s digress a bit. In the first place, we must realize that back then, people often measured from summer to summer. Rome’s various legendary foundation dates must, therefore, be written as a “double number”. 814/813 was the conclusion of the investigations by the Sicilian historian Timaeus; the Roman writers Fabius Pictor and Cincius Almenus believed their hometown had been founded in 748/747 and 729/828; Dionysius of Halicarnassus concluded the correct date was 752/751; and Marcus Terentius Varro, finally, believed that Romulus built the city in 754/753.
What made Varro believe that Rome was founded in 754/753? He first established that the first pair of consuls of the Roman Republic had ruled in 509/508. To this, he added thirty-five years for each of the seven known kings. It is self-evident that this method is unsound, and it is rather ironical that 753 has become canonical, because it is the only date about which we know why it must be incorrect. The other dates at least have the benefit of the doubt.
But things are even worse. We know that Varro’s 509/508 must be incorrect. During the Republic, the Romans dated documents with the names of the magistrates. 509/508 was, therefore, the year in which Brutus and Collatinus had been consul. Varro used a list of magistrates who had ruled before 300/299 – or hadn’t, because the list included one year of anarchy. The ancients knew that this list was incomplete: three or four colleges of magistrates were missing. They had several solutions: The historian Livy thought that the period of anarchy had not lasted one but five years. The anonymous Chronographer of 354 added four pairs of consuls. Varro added four years in which dictators had been governing the city – a constitutional absurdity – and continued to add four years of anarchy. Because he solved the same problem twice, his chronology is four (perhaps three) years too long. Rome’s first consuls did not rule in 509/508 but in 505/504.
It is easy to convert Varronian chronology into our chronology. In the age before 390 (according to Varro) = 387/386 BCE, we must subtract three or four years from the traditional, Varronian dates. We also know that the missing magistrates were in office between 390V=387/376 BCE and 350V=347/346 BCE; after this year, the Varronian chronology can be converted to our era by merely ignoring the dictator years.
All this is indeed a bit boring, but it is important, because it helps us connect Rome’s conquest of Central Italy to the history of the Mediterranean world in general. In 387/386 BCE, Rome was sacked by Senones, a Gallic tribe that lived near the Adriatic Sea. The Romans were deeply shocked, especially because they had no idea why they had been targeted. (The explanations offered by historians like Livy are nothing but moralistic anecdotes.) From Justin’s Excerpt of the Histories of Pompeius Trogus (20.5), we know that these Gauls were in 386 in southern Italy, where they joined a Syracusan army that was besieging Croton. It looks as if the Senones had been hired earlier – there was a Syracusan colony near their homeland – and had orders to sack Rome during their march to the deep south. Rome, which had just conquered Veii, may have been too powerful in the eyes of the Syracusan tyrant Dionysius. This is a hypothesis, based on only one source, but historians who stick to the Varronian chronology and continue to date the sack of Rome to the wrong year, will not even notice that the two stories are almost contemporary and may be connected.
The most ironic aspect is that many modern editions of Livy’s History of Rome from its Foundation offer Varronian dates in the margin or in notes. The author who offered a correct chronology, is explained with a chronology that it notoriously unreliable.