Complex sentence: Levanger can probably be traced back to the Iron Age, and with certainty back to the Viking age, although it was located somewhat different to the current town center, probably in relation to the Halsstein bygdeborg (hill fort).
Split into simpler sentences: Levanger can probably be traced back to the Iron Age, and with certainty back to the Viking age. The historic town site was located somewhat different to the current town center, probably in relation to the Halsstein bygdeborg (hill fort).