The Campus Martius was a publicly owned area of ancient Rome about 2 square kilometres in extent. In the Middle Ages, it was the most populous area of Rome. The IV rione of Rome, Campo Marzio, which covers a smaller section of the original area, bears the same name.
According to Rome’s foundation myth, prior to the founding of the city, Rhea Silvia had her twin sons, Romulus and Remus, taken by the King of Alba Longa. The boys were later discarded in the swelling Tiber River, which would later run along the Campus’ western boundary. Washing ashore further downriver, the brothers would return decades later to found a new city. Romulus, who became Rome’s sole king (after killing his brother Remus), ruled for many years until sometime in the seventh century B.C. As he came to the end of his life, a storm cloud descended upon the center of the open field outside the city’s pomerium in order to lift the elderly king to heaven.
