What chronology system existed in Ancient Rome?

It is worth knowing that the Ancient Romans were a fairly civilized and educated people. There was no such calendar in our usual understanding at that time. This people was guided by the life of nature. That is, according to the seasons that followed each other. Of course, these people understood that there is a pattern. They chose the starting point of the year when they founded the main city of their state. The first summer reckoning system consisted of only ten months. They had twelve months around the sixth century BC.