Of the fortifications we know much more. In the north wall of Nimroud fifty-eight towers have been traced, and at Kouyunjik there are large remains of three walls, the lower part being of stone, and the upper of sun-dried bricks. At Khorsabad there are the remains of a wall, still high, built of blocks of stone 3 to thick, and the evidences wanting as to finishing of these is completely supplied by the sculptures, which show an extraordinary resemblance to medieval works of the same class. Tier upon tier of walls are represented, enclosing a great tower or keep in the centre. The entrances are great arched gateways flanked by square towers. These and the other towers have overhanging parapets just like the mediaeval machicolations, and are finished at top with battlements, remains of which have been found at Nimrud and Kouyunjik, and at Assur, the capital of Assyria before Nineveh.