Excavations at Yenikapı in Istanbul, Turkey, related to the Marmaray Project, have unearthed remains of Constantinople's Theodosian Harbour, including 37 Byzantine shipwrecks of 5th‐ to 11th‐century date. Eight of these shipwrecks, six round ships and two of the first long ships, or galleys, to be excavated from the Byzantine period, were studied by archaeologists from the Institute of Nautical Archaeology. These well‐preserved shipwrecks are an important new source of information on the maritime commerce of Constantinople and the gradual shift from shell‐based to skeleton‐based shipbuilding in the Mediterranean during the second half of the first millennium AD.