Annual calendar years. An annual timepiece calendar is less complicated and expensive than a perpetual timepiece calendar, which will not require manual adjustment till 2100. That year will not be a leap year, even though its number is evenly divisible by 4. Ancient calendars (static) may always have been annual, even after the length of the calendar year was fixed at (avg.) 365.25 days by the Julian Calendar (46 BC). Early Romans observed an 8-day market week, called the nundinal cycle, until the seven-day week was adopted during the reign of Emperor Constantine the Great (306-337). A goal of modern calendar reform
Roman calendar role as "pontifex maximus", ordered a reformation of the calendar in 46. This was undertaken by a group of scholars apparently including the Alexandrian Sosigenes and the Roman M. Flavius. Its main lines involved the insertion of ten additional days throughout the calendar and regular intercalation of a single leap day every fourth year in order to bring the Roman calendar into close agreement with the solar year. The year 46 was the last of the old system and included 3 intercalary months, the first inserted in February and two more—' and '—before the kalends of December. After Caesar's assassination,