In one division the bedding of the bricks is strictly horizontal; in the next it is slightly concave, and forms a very flat reversed arch, of which the extrados rests upon the ground.

The alternation of these two methods is regularly repeated.

The object of this arrangement is obscure; but it is said that buildings thus constructed are especially fitted to resist earthquake shocks.

However this may be, the fortress is extremely ancient, for in the Fifth Dynasty, the nobles of Abydos took possession of the interior, and, ultimately, so piled it up with their graves as to deprive it of all strategic value.

A second stronghold, erected a few hundred yards further to the south-east, replaced that of Kom es Sultan about the time of the Twelfth Dynasty, and narrowly escaped the fate of the first, under the rule of the Ramessides.