This paper seeks to explore the contribution to our understanding of the Roman coastal forts between the Wash and the north Kent coast which can be provided by a study of the surviving building materials which can be attributed to them. Although some of our sites have little or no masonry surviving above ground level, we argue that the materials to which we draw attention were derived from their defensive wall circuits which were constructed between the late second and the late third century. While certain of our sites eventually belonged to the Late Roman Saxon Shore of the Notitia Dignitatum, others were not thus designated. All our sites have long histories but, since the materials in question probably derive from the initial, stone-building phase of these forts, it is likely that our conclusions will relate to, and inform our interpretation of, their primary function. Our survey includes the forts at Brancaster, Burgh Castle, Bradwell, Reculver, and Richborough, all of which can be assigned to the Saxon Shore system with reasonable confidence, as well as the fort, rather than defended civil port at Caister-on-Sea. We also consider evidence of materials which we argue were derived from Walton Castle, which has been identified by some as the Portus Adurni of the litus saxonicum listed in the Notitia Dignitatum, and which was lost to the sea by the nineteenth century.