Year 321 (CCCXXI) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Crispus and Constantinus (or, less frequently, year 1074 Ab urbe condita). The denomination 321 for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
March 7 - Constantine I signs legislation directing urban residents to refrain from work, and businesses to be closed, on the "venerable day of the Sun". An exception is made for agriculture.
Constantine I assigns convicts to grind Rome's flour, in a move to hold back the rising price of food in an empire whose population has shrunk as a result of plague.
