One of our single most important sources of information on Roman religion and its temporal associations is the Roman calendar; and thanks to the survival of numerous epigraphic versions, it has received much modern scholarly attention.1 This calendar, however, was the one revised by Julius Caesar (hence, its name “the Julian calendar”), consisting of 365 days with an additional intercalary day inserted every four years. It was established as Rome’s new calendar as of January 1, 45 B.C. and continued to be the calendar of the Roman Empire and on through the Middle Ages until revised slightly by Pope Gregory XIII in 1582.