The Acropolis, as in neolithic days the first settlers found it, was, it will be seen in Fig. 1, a long, rocky ridge, broken at intervals[10]. It could only be climbed with ease on the west and south-west sides, the remaining sides being everywhere precipitous, though in places not absolutely inaccessible. For a primitive settlement it was an ideal situation. Two things remained for the settlers to do: first, they had to level the surface by hewing away jagged rocks and filling up cracks with earth and stones to make sites for their houses and their sanctuaries; and second, they had to supplement what nature had already done in the way of fortification; here and there to make the steep rocks steeper, build a wall round their settlement, and, above all, fortify that accessible west and south-west end and build an impregnable gateway. Kleidemos[11], writing in the fifth century B.C., says, ‘they levelled the Acropolis and made the Pelasgicon, which they built round it nine-gated.’ They levelled the surface, they built a wall round it, they furnished the fortification wall with gates. We begin for convenience sake with the wall. In tracing its course the process of levelling is most plainly seen. The question of the gates will be taken last. [Illustration: FIG. 1.] In the plan in Fig. 2 is shown what excavations have laid bare of the ancient Pelasgic fortress. We see instantly the inexactness of the main statement of Thucydides. It is not ‘_what is now the Citadel_’ that was the main part of the old burgh, but something substantially smaller, smaller by about one-fifth of the total area. We see also that this Thucydides could not know. The Pelasgic wall following the broken outline of the natural rock was in his days covered over by the artificial platform reaching everywhere to the wall of Kimon. At one place, and one only, in the days of Thucydides, did the Pelasgic wall come into sight, and there it still remains above ground, as it has always been, save when temporarily covered by Turkish out-works. This visible piece is the large fragment (A), 6 metres broad, to the south of the present Propylaea and close to the earlier gateway (G). In the days of Thucydides it stood several metres high. Of this we have definite monumental evidence. The south-east corner of the wall of the south-west wing of the present Propylaea is bevelled away[12] so as to fit against this Pelasgic wall, and the bevelling can be seen to-day. This portion of the Pelasgic wall is of exceptional strength and thickness, doubtless because it was part of the gateway fortifications, the natural point of attack. [Illustration: FIG. 2.]