Unlike many cities of Roman Britain, Londinium was not placed on the site of a Celtic oppidum. Prior to the arrival of the Roman legions, the area was almost certainly lightly rolling open countryside traversed by numerous streams now underground. Ptolemy lists it as one of the cities of the Cantiacs, but Durovernum (Roman Canterbury) was their tribal capital (). It is possible that the town was preceded by a short-lived Roman military camp but the evidence is limited and this topic remains a matter of debate.