The centre of the City of Rome was the Mundus. Plutarch describes its origin in the Life of Romulus:

"Romulus, having buried his brother Remus, together with his two foster-fathers, on the mount Remonia, set to building his city; and sent for men out of Tuscany, who directed him by sacred usages and written rules in all the ceremonies to be observed, as in a religious rite. First, they dug a round trench about that which is now the Comitium, or Court of Assembly, and into it solemnly threw the first-fruits of all things either good by custom or necessary by nature; lastly, every man taking a small piece of earth of the country from whence he came, they all threw in promiscuously together. "This trench they call, as they do the heavens, Mundus; making which their centre, they described the city in a circle round it". Then the founder fitted to a plough a brazen ploughshare, and, yoking together a bull and a cow, drove himself a deep line or furrow round the bounds; while the business of those that followed after was to see that whatever earth was thrown up should be turned all inwards towards the city; and not to let any clod lie outside. With this line they described the wall, and called it, by a contraction, Pomoerium, that is, postmurum, after or beside the wall."

From the very foundation of Rome this area was considered to be the point where the underworld met the real world. The monument was split into two parts; the top was known as the Umbilicus Urbus, and the lower with the name of Mundus

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