Istanbul Seawalls, prolonged along the northern and the southern shores of historic peninsula, have been witnesses to all periods of historic Istanbul since its establishment as a Greek colony at the tip of the peninsula. They were influenced by the historical developments of the city as the other parts of Istanbul City-Walls. During the Middle Ages, the defense system had repairs and renovations. Their maintenance was not carried on regularly in the Ottoman era; yet the walls survived the vicissitudes of time with their firm structures. Starting from the sixteenth century, the martial importance of the city-walls decreased gradually with the result of proliferation of firearms, and from the nineteenth century, they lost their significance militarily. Then settlements developed in the immediate vicinity of the walls, and some parts went into private ownership. Moreover modernization of the city accelerated damages and losses on the walls. Today only parts of Istanbul Seawalls are intact. Within this study, the history and the current state of Istanbul Seawalls have been searched in terms of their ownership status, and their property issues have been analyzed.