The four Port cities where the Venetian and Hanseatic trade routes met are Venice, Cologne, Bruges, and Milan.
Venice and other Coastal Italian city-states had a Monopoly over commerce in their region ( the Mediterranean Sea) for ages. As a result of this Monopoly, in or around 1200, European Merchants in the North began to organize themselves under the "North European Cities Federation" called the Hanseatic League to control their trade routes. More specifically they controlled the trade between the Baltic and North Seas.