It lies on the territory of today's Netherlands and Germany. This "limes" was a river border ("limes ripa") on the Rhine, defended by a chain of camps, that ran from the North Sea (Katwijk-Brittenburg camp) to Vinxtbach (opposite Rheinbrohl fort on the Upper Germanic Limes), forming the border between the Roman provinces of "Germania Inferior" and "Germania Superior". By contrast with the Upper Germanic-Rhaetian Limes, it was not marked by a solid palisade or wall. Neither can any defensive ditch or rampart be identified. The guards were stationed in nearby "castra" and watchtowers usually built immediately on the Rhine. The "limes" was served by a well-developed military road. Each camp had its own river port or landing stage and a storage area, because the Rhine not only formed the border but was also the most important transport and trade route in the region. In the first section, between the camps of "Rigomagus" (Remagen) and "Bonna" (Bonn), there were only a few camps. In the second, middle, section between "Bonna" and "Ulpia Noviomagus Batavorum" (Nijmegen), there were considerably more. Here there were also larger legion camps; with one exception, all were cavalry barracks. The landscape of the third section between "Ulpia Noviomagus Batavorum" and "Mare Germanicum" (the North Sea) was characterised by numerous small streams and boggy marshland. Consequently, in this area there was only one cavalry camp. Border security here consisted mainly of tightly packed, relatively small cohort forts.