The topographical features of the site that was to become Norfolk's county town were such as to encourage settlement. Around it lay a highly fertile soil, another result of valley formation. By the early Saxon period the sea had receded to its present level, but the continuing free-flow of the tide kept parts of Norwich's site marshy for several centuries, making the medieval river wider and shallower than today. Opposite, on the northern bank, another ridge continued the direction along Fybriggate.
Crossroads tend to be magnets for settlement.
So too proximity to a navigeable river , when water traffic became as important as roads, if not more so, in the post-Roman period. Also influential was the fact the north-south river crossing was easier here than anywhere else on the River Wensum, above the point where it joined with the Yare. Despite the legendary associations of Norwich castle, there is no evidence of such a fortification in that locale until the Normans. By circa 500 A.D., there is evidence of occupation in the area, at least on the northern bank of the Wensum. The bounds of settlement north of the Wensum remained confined, throughout the medieval period, to the area defined by the gravel terrace.