The Scope of Medieval Cities. By the tenth century urbanization in Europe followed two patterns. Almost every city of any substantial size (5,000-10,000 residents or larger) in Christian Europe was located south of the Alps or along the Mediterranean, while those few surviving cities north of the Alps were based around administrative centers or were located in Flanders and along the western Rhine. Scholars have many theories about the reasons for this division; the influence of Roman foundations, traditions of urbanism, and the extent of Viking or other invasions are three of the most convincing. By the fourteenth century, this pattern remained roughly the same, but the number and size of urban centers all over Europe had grown enormously. Spurred by administrative centralization and economic revival throughout Europe, cities such as London and Paris reached 30,000 and 70,000-80,000 residents...