Nowhere else is there anything to be discovered beyond the remains of brick walls, which have always been laid out in the form of a parallelogram.[36] These walls are sometimes between sixty and seventy feet thick.[37] In some cases their position is only to be traced by a gentle swelling in the soil; at Sais, however, they seem to have preserved a height of fifty-seven feet in some parts.[38] No signs of towers or bastions are ever found. At Heliopolis there were gates at certain distances with stone jambs covered with inscriptions.[39] The best preserved of all these _enceintes_ is that of the ancient city of Nekheb, the Eilithyia of the Greeks, in the valley of El-Kab. The rectangle is 595 yards long by 516 wide; the walls are 36 feet-thick.[40] About a quarter of the whole _enceinte_ has been destroyed for the purposes of agriculture; the part which remains contains four large gates, which are not placed in the middle of the faces upon which they open. In all the paintings representing sieges these walls are shown with round-topped battlements, which were easily constructed in brick. [36] Plate 55 of the first volume of Lepsius's _Denkmæler_ contains traces of the _enceintes_ of Sais, Heliopolis, and Tanis. See also the _Description de l'Égypte_, _Ant._, Ch. 21, 23, 24. [37] At Heliopolis they were 64 feet thick (_Description_), at Sais 48 feet (_ibid._) while at Tanis they were only 19 feet. [38] ISAMBERT, _Itinéraire de l'Égypte_. [39] MAXIME DU CAMP, _Le Nil_, p. 64. [40] LEPSIUS, _Denkmæler_, vol. ii. pl. 100.--EBERS, (_Ægypten_,) makes the _enceinte_ of Nekheb a square. The only fort, properly speaking, which has been discovered in Egypt, appears to be the ruin known as _Chounet-es-Zezib_ at Abydos.[41] This is a rectangular court inclosed by a double wall, and it still exists in a fair state of preservation, to the west of the northern necropolis (Fig. 28). After examining many possible hypotheses, Mariette came to the conclusion that this was a military post intended to watch over the safety of the necropolis, and to keep an eye upon the caravans arriving from the desert. Robber tribes might otherwise be tempted to make use of any moment of confusion for the pillage of the temple. There were curious arrangements for the purpose of guarding against a _coup-de-main_. Within the outer wall, which is provided with small gateways, there is a covered way extending round the whole fort, and commanded by the inner wall. Before the inner court could be reached, an enemy had to traverse a narrow and crooked passage in the thickness of the wall, which was well calculated to secure the necessary time for a moment of preparation in case of surprise (Fig. 29). [41] MARIETTE, _Abydos, Description des Fouilles_, vol. ii. pp. 46-49, and plate 68. [Illustration: FIG. 28.--Military post at Abydos; perspective from the plans, etc., of Mariette.]