The city's greatest length from north to south was about a mile and a quarter, and its greatest width some three-quarters of a mile, the whole circuit of the existing defences, including the lower-lying area, extending to some three and a half miles. This is a remarkable size for a mountain city, and although some portions of the area cannot have been occupied by buildings, the fortification of so extensive a site is an indication of the power of the Hittite empire and its capital. About fourteen feet in thickness, the wall is preserved in many places to a hight of more than twelve feet. It consists of an inner and an outer wall, filled in with a stone packing. The outer face was naturally the stronger of the two, and huge stones, sometimes five feet in length, have been employed in its construction. The wall was strengthened by towers, set at more or less regular intervals along it, their position being sometimes dictated by the contour of the ground. Round a great part of the circuit there are traces of an outer defensive wall of lighter construction and with smaller towers, but this was not continuous, being omitted wherever the natural fall of the ground was a sufficient protection to the main wall. [Illustration: FIG. 53. CONJECTURAL RESTORATION OF A HITTITE GATEWAY VIEWED FROM INSIDE. It is possible that brick was employed for the upper structure of the city-wall and its towers, as suggested in the restoration. In such a case it is not unlikely that the stepped battlements of Mesopotamia were also adopted. (After Puchstein.)] Projecting towers also flanked the main gateways, which exhibit a characteristic feature of Hittite architecture. This is the peculiar form of the gateway, consisting of a pointed arch with gently sloping sides, the latter formed by huge monoliths bonded into the structure of the wall.[35] It would seem that brick was probably employed for the upper structure of both wall and towers; and in other buildings of the city, such as the great temple to the north-west of the citadel, brick was used for the upper structure of the walls upon a stone foundation. Whenever the use of brick was adopted in one of the northern lands of Mesopotamia, where stone is plentiful, the latter was always used in the foundations. It is not improbable, therefore, that the stepped battlements of Assyria and Babylon were also borrowed, as that was the most convenient and decorative way of finishing off the upper courses of a fortification-wall built of that material.