a narrow sandy isthmus. By means of the causeway the channel between island and mainland was formed into two harbours, of which the larger, or southern, was further enclosed by two strongly built moles that are still in good part entire.

The extreme length of the city was little less than a mile, and the whole intramural area is still thickly strewn with architectural remains. The walls, both of the island and on the mainland, can be traced throughout their whole circuit; and in many places, especially