Over the past few decades, there has been a significant amount of research on the Roman Lower Danube frontier by international teams focusing on individual forts or broader landscape survey work; collectively, this volume represents the best of this collaboration with the aim of elevating the Lower Danube within broader Roman frontier scholarship.

The inextricability of the connection between the Roman limes and the lands it ran through is easily observed and perfectly illustrated in Bulgaria. For a considerable distance it follows the Danube; both a major natural obstacle and at the same time a convenient communication route, it was easily defendable and facilitated control of trade routes.

The present day Danube border of Bulgaria constituted, at different times between the beginnings of 1st century AD to the last quarter of 7th century, an integral part of the northern border of the Roman Empire ? the so-called Danube limes.00A close scrutiny of the written sources and epigraphic evidence shows that until 3rd century AD the term limes occurs rarely and when used it stands for ?a military road? or ?land border?. Not a single occurrence, however, as much as even hints at limes referring to a set of defence facilities or a particular military and administrative unit. After 4th century the term came to be widely used. Nevertheless, it lacks fortification reference and was never used to mean a system of border fortifications. Rather, it stood for a particular area which comprised parts of a border province and fell within the jurisdiction of a special military commander with the title of dux (in some cases ? comes). The term limes as used in the late antiquity has to be considered, therefore, to have military and administrative connotation in the sense of ?a military zone? which outlines the territorial scope of the competences of the specific dux.00In any event, the term limes in the sense of a fortified defence frontier with fortification and support infrastructure constructed with care, of specific planning scheme and connected with a military road, is presently widely popular and has acquired axiomatic value in modern historiography.

Austria is particularly fortunate in the survival along the Danube of the remains of many Roman military installations. These include forts and towers, some parts surviving up to two stories high. They are a most remarkable survival and deserve to be better known and more visited.