Romulus

With this line they mark out the course of the wall, and it is called, by contraction, pomerium, that is post murum, behind or next the wall. And where they purposed to put in a gate, there they took the share out of the ground, lifted the plough over, and left a vacant space. And this is the reason why they regard all the wall as sacred except the gates; but if they held the gates sacred, it would not be possible, without religious scruples, to bring into and send out of the city things which are necessary, and yet unclean.

Now it is agreed that the city was founded on the twenty-first of April, and this day the Romans celebrate with a festival, calling it the birthday of their country. And at first, as it is said, they sacrificed no living creature at that festival, but thought they ought to keep it pure and without stain of blood, since it commemorated the birth of their country. However, even before the founding of the city, they had a pastoral festival on that day, and called it Parilia.