Harbours of the Aegean in Late Antiquity and the Medieval Period presents the first comprehensive introduction to the archaeological study of harbours and maritime connectivity in the Aegean that goes beyond the investigation of individual sites. By synthesising the evidence for different harbour infrastructures and their functionality, a framework for the correct interpretation and thus hierarchical interaction of coastal facilities is developed. This offers a general understanding of the complex picture of seascapes in the Eastern Mediterranean in Late Antiquity and the medieval periods. In contrast to most studies, the book examines not only port cities and major harbour sites, but incorporates and focuses also on local and regional infrastructures as the diachronic backbone of the maritime economy. This results in a comprehensive analysis of historical and architectural developments, as well as an in-depth understanding of port networks and maritime connectivity in the Byzantine East. A detailed archaeological examination of the province of Thessaly is used as a representative case study. It constitutes not only an ideal region to gain a balanced spread of information for the Early to the Late Byzantine periods, but also to compare independent regional and imperial building activities. Furthermore, by featuring very diverse maritime and coastal landscapes, it encompasses a large variety of coastal sites and thus reflects the full spectrum of maritime activities in Late Antiquity and the Middle Ages. These include gulfs, open coastlines, peninsulas, archipelagos and river deltas.