Subiect: Augustus, after the settling of the Danubian frontier and consolidation of those formed by the Rhine and the Euphrates, decided to maintain the Empire within these borders. At the end of his reign, he thought his successor should not extend the existing frontiers but protect them. For these issues to be respected, they needed to realize some demarcation system. In the roman epoque, when the natural borders (ripa) were absent, the land was marked by a turf-wall (vallum) with its ditch (fossa). Taking into account the needs that made possible the construction of these turf-walls, they can be grouped in three categories such as: I. Turf-walls that have the function of a limes. This type is often met where the natural border (ripa) needs to be completed. Such examples are the va//um of the Transalutan limes, „Brazda lui Novac de Nord', and ,,Brazda lui Novac de Sud". 2. Turf-walls that have function as limltibus. These turf-walls role is "bureaucratic'', making the breath of the controlied area made by the Romans between the limes and Barbaricum. Examples of this kind of turf-walls are lsac's ford -Sasac's Lake and the one from Stoicani -Ploscuteni. 3. Turf-walls which work as a defensive element for a strategic area. They are smaller than the others and have a specific form - as an arch being centered upon the protection objective. This turf-walls are characteristic to the south of Moldavia where there was a need for some „bridge ends" build in Barbaricum because of the conditions. Examples are: Traian-Tulucesti and Cahul Lake-Cartal Lake turf-walls.