Ancient Olbia, city plan
A = Classical wall with Hellenistic repairs and additions. The eastern section was submerged along with the rest of the Lower City.
SW = Part of the walls (located by underwater investigation). The area within the walls is divided into four distinct parts: the Acropolis on a hill to the southwest, the Upper City on a rise in the northwest, the Lower City along the riverside, and the Middle City between the natural terraces in the rocky bank that descends to the River Hypanis.
R = Roman walls. These enclose a small portion of the former city, now in decline, as well as the fortified Acropolis – the Olbians' last refuge.