Defensive infrastructure in the hinterland of the late Roman province of Germania Secunda hinged upon the widespread use of burgi. These defended settlements played a role in transforming villa estates, depopulated zones, and the expansion of the military footprint. They are common in the late third- and fourth-century landscape, spread throughout the loess belt of Belgium, Dutch Limburg, and the Rhineland, yet little has been done to quantify them. This article is dedicated to the chronology, morphology, and functional aspects of burgi, primarily in the loess plain of the Lower Rhine region. The author assembles data from a wide variety of burgi, to characterize them and reach meaningful conclusions about what they represent within the landscape, in the hope that it will act as a pilot project for future work in the field.