In the Middle Ages, Great Yarmouth was a town of considerable economic and strategic significance; in 1334, it ranked fourth in English provincial towns in its wealth. This work examines in detail the construction and, more especially, material composition of the Great Yarmouth town walls. Contents: 1) Great Yarmouth: geographical, historical and economic background; 2) The structure and composition of the walls; 3) The town wall: 'a modern geological perlustration'; 4) The wall fabric - an analysis; 5) Other defensive systems: early walls, towers, rampires, pseudo-ravelins and a moat; 6) The financial provision for wall construction; 7) Records of expenditure on wall construction, modification and repair; 8) Reservations and conclusions; Glossary, references and ancillary bibliography.