The Indus Civilization (Cambridge History of India, Supplementary Volume) c11.s1.7

c11.s1.7

On the west side of the citadel, to the south of the Granary, a baked-brick tower or salient, still standing 10 ft. high, has been partially uncovered, and to the north of this tower a small postern has been identified. The implication is that the platform of the citadel was, in one way or another, of a defensible character throughout its circuit, but that the defences were of a less simple and uniform kind than is suggested by the equivalent system at Harappā.