ABSTRACT
Access to the sea and viable harbors was essential for medieval Mediterranean coastal cities and settlements. Urban harbors dating from the Classical to Roman Imperial periods have tended to receive the most scholarly attention, often due to the scale and sophistication of artificial harbor works and other infrastructure; the applications of hydraulic concrete in port construction in the late Republic and Early Empire have been a particular focus of research. This tradition of centrally planned artificial harbor construction – whether by provincial or imperial governments – continued well into the Byzantine era, even as it disappeared or was vastly reduced in other regions of the Mediterranean, due in large part to the state-subsidized annona trade used to feed much of Constantinople's population into the early 7th century AD. The four major commercial harbors constructed in Constantinople in the 4th or early 5th century provided an estimated 4–5 km of wharf space for the city's waterfront.
