Agri Decumates, the Roman term for the wedge shaped territory between the rivers Rhine to the west, Danube to the south and Main to the north. Originally left unoccupied after the Roman retreat to the Rhine after 16 CE, it protruded into Roman territory, significantly lengthening the travel times between the Roman bases along the Rhine and the Province of Raetia south of the Danube. Thus it was occupied, after the Year of the four Emperors and the Batavian uprising from 70 CE onwards, to built direct roads between the legionary fortresses Argentorate and Mogontiacum in Germania Superior and Augusta Vindelicum, the capital of Raetia. Shortly later the borders were secured by the Upper Germanic-Rhaetian Limes, quickly accelerating civil settlement in the hinterland. Although only part of the Roman Empire for less than 200 years, it became a well settled wealthy frontier zone with multiple new civitates founded.
Since this is also where my home is today, I begun mapping Roman sites there a long time ago. My goal is to make a complete large scale map, in 1:250.000, including all known Roman sites.
The excerpt below shows what are today the central and southern parts of the modern German state of Hesse during Roman tomes, in about 200 CE.