During the Roman Republic, several dates were given for the founding of the city between 753 BC and 728 BC. Finally, under the Roman Empire, the date suggested by Marcus Terentius Varro, 753 BC, was agreed upon, but in the Fasti Capitolini the year given was 752. Although the proposed years varied, all versions agreed that the city was founded on April 21, the day of the festival sacred to Pales, goddess of shepherds; in her honour, Rome celebrated the Par ilia (or Palilia). (The Roman a.u.c. calendar, however, begins with Varro’s dating of 753 BC.)
According to legend, the foundation of Rome took place 438 years after the capture of Troy (1182 BC), according to Velleius Paterculus (VIII, 5). It took place “shortly” before an eclipse of the sun; some have identified this eclipse as the one observed at Rome on June 25, 745 BC, which had a magnitude of 50.3%. Varro may have used the consular list with its mistakes, calling the year of the First consuls “245 a.u.c.”.
According to Lucius Tarrutius of Firmum, Romulus was conceived on the 23rd day of the Egyptian month Choiac, during a total eclipse of the sun. This eclipse occurred on June 15, 763 BC, with a magnitude of 62.5% at Rome. He was born on the 21st day of the month of Thoth. The first day of Thoth fell on 2 March in that year (Prof. E. J. Bickerman, 1980: 115), That implies that Rhea Silvia’s pregnancy lasted for 281 days. Rome was founded on the ninth day of the month Pharmuthi, which was April 21, as universally agreed. The Romans add that, about the time Romulus started to build the city, an eclipse of the Sun was observed by Antimachus, the Teian poet, on the 30th day of the lunar month. This eclipse (see above) had a magnitude of 54.6% at Teos, Asia Minor. Romulus vanished in the 54th year of his life, on the Nones of Quintilis (July), on a day when the Sun was darkened. The day turned into night, which sudden darkness was believed to be an eclipse of the Sun. It occurred on July 17, 709 BC, with a magnitude of 93.7%. (All these eclipse data have been calculated by Prof. Aurél Ponori-Thewrewk, retired director of the Planetarium of Budapest.) Plutarch placed it in the 37th year from the foundation of Rome, on the fifth of our month July, then called Quintiles, on “Caprotine Nones”. Livy (I, 21) also states that Romulus ruled for 37 years. He was slain by the Senate or disappeared in the 38th year of his reign. Most of these have been recorded by Plutarch (Lives of Romulus, Numa Pompilius and Camillus), Florus (Book I, I), Cicero (The Republic VI, 22: Scipio’s Dream), Dio (Dion) Cassius and Dionysius of Halicarnassus (L. 2). Dio, in his Book I of his Roman History, confirms these data by telling that Romulus was in his 18th year of age when he founded Rome. Therefore, three eclipse records indicate that Romulus reigned from 746 BC to 709 BC. Surprisingly this is very close to the calculation of the founding given by Rome’s first native historical writer, Quintus Fabius Pictor, who wrote that Rome was founded in the first year of the eighth Olympiad, 747 BC (Dionysius of Halicarnassus, Book 1, ch. 74,2).