This chapter investigates the archaeological landscapes of the frontiers of the Sasanian Empire. Drawing on evidence from current and archived archaeological surveys, in combination with high-resolution remote sensing datasets such as CORONA spy photography, we compare the organisation of settlements and defensive structures of the Sasanian frontier zones in response to a variety of external pressures. These varied from the Roman Empire in the west to less centralised entities, including nomadic groups, in the south-west and north-east. Following a general discussion of the multiple manifestations of Sasanian frontiers drawn from southern Mesopotamia (Iraq), northern Syria and north-eastern Iran, the main focus of the chapter is on the complex frontier landscape of the southern Caucasus, particularly the area of modern Azerbaijan, Georgia and Daghestan. We discuss the role of linear barriers, including the Gorgan Wall in north-eastern Iran and the Ghilghilchay and Derbent Walls in the Caucasus, irrigation systems, and alignments of fortifications and settlements in shaping their local landscapes. By placing the archaeological remains of the Sasanian Empire in a wider context we are able to examine the relationships between military installations, settlement patterns, infrastructure and geographical features such as mountain ranges and rivers. Comparing the different case studies allows us to conclude with some general statements on the nature of Sasanian power in the frontier territories of the empire.