ELI5: Explain Like I'm 5

Roman calendar

The Roman Calendar was a calendar used by the ancient Romans to keep track of time. It was first used during the 8th century BC and changed over time until it was replaced by the Julian Calendar in 45 BC. The Roman Calendar used a system of months with names like January, February, and March, just like the calendar we use today. Instead of the twelve months we have today, the Roman Calendar had ten months and the remaining months were added in around the time of Julius Caesar. Each month had a different number of days and was either 29 or 31 days long. The months weren't divided into weeks, like our calendar is. Instead they had a system of days called 'nundinae' which were a cycle of 8 days. They also had a special month every few years called an intercalary month which was used to make up for the extra days that didn't fit into the regular calendar.