pomerium

thumb|Map of Rome in the time of the Roman Republic. The pomerium at that time is marked in pink; the Capitoline Hill|Capitoline and Aventine are extra pomerium, 'beyond the wall', with their boundaries in yellow. The pomerium or pomoerium was a religious boundary around the city of Rome and cities controlled by Rome. In legal terms, Rome existed only within its pomerium; everything beyond it was simply territory (ager) belonging to Rome.

==Etymology== The term pōmērium is a classical contraction of the Latin phrase '' (). The Roman historian Livy writes in his Ab Urbe Condita that, although the etymology implies a meaning referring to a single side of the wall, the pomerium was originally an area of ground on both sides of city walls. He states that it was an Etruscan tradition to consecrate this area by augury and that it was technically unlawful to inhabit or to farm the area of the pomerium, which in part had the purpose of preventing buildings from being erected close to the wall (although he writes that, in his time, houses were in fact built against the wall on the line). Other writers suggest a derivation from , "against the wall".