'I know it – behold!' Oldenburg said, and, tightening his arm, swung Daniel round so that both of them were looking west, across the Inmost Ward. They were near Salt Tower, which was the southeastern corner of the squarish Tower complex. The southern wall, therefore, stretched away from them, paralleling the river, connecting a row of squat round towers. Off to their right, planted in the center of the ward, was the ancient donjon: a freestanding building called the White Tower. A few low walls partitioned the ward into smaller quadrangles, but from this viewpoint the most conspicuous structure was the great western wall, built strong to resist attack from the always difficult City of London. On the far side of that wall, hidden from their view, a street ran up a narrow defile between it and a somewhat lower outer wall. Stout piles of smoke and steam were building from that street – which was lined with works for melting and working precious metals. It was called Mint Street. 'Their infernal hammers keep me awake – the smoke of their furnaces comes in through the embrasures.' Walls hereabouts tended to have narrow cross-shaped arrow-slits called embrasures, which was one of the reasons the Tower made a good prison, especially for fat men.