What became the canonical date, and one still quoted in many modern textbooks, partly goes back to a scholarly treatise, the Book of Chronology, by none other than Cicero’s friend and correspondent Atticus. It does not survive, but it is supposed to have pinpointed Romulus’ foundation of the city to the third year of the sixth cycle of Olympic Games; that is to say, 753 BCE. Other calculations narrowed this down further, to 21 April, the date on which modern Romans still, to this day, celebrate the birthday of their city, with some rather tacky parades and mock gladiatorial spectacles.
