45 BC

Year 45 BC was either a common year starting on Thursday, Friday or Saturday or a leap year starting on Friday or Saturday (link will display the full calendar) (the sources differ, see leap year error for further information) and the first year of the Julian calendar and a leap year starting on Friday of the Proleptic Julian calendar. At the time, it was known as the Year of the Consulship of Caesar without Colleague (or, less frequently, year 709 Ab urbe condita). The denomination 45 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.