How did the ancient Romans count the years? In the Western world, years are counted from the birth of Christ. And before that? How were time and days measured in ancient Rome? Find out in these lines. In the Western world, years are counted from the birth of Christ. And before that? How were time and days measured in ancient Rome? Find out in these lines. The ancient Romans originally used a system of calculating time based on the year of foundation of their city: ab urbe condita, which means “from the foundation of the city” (753 BC). Each event was dated with respect to that year, considered the fundamental reference point of Roman chronology. However, with the passage of time and the transformations of the empire, the calculation system underwent changes. In particular, under the emperor Diocletian, it was decided to adopt a new reference point: 284 AD, the year of his accession to the throne. This sign of discontinuity marked the beginning of the so-called “Diocletianic Era”, used above all in official documents and in the calendars of