The original North-East Line was constructed in 1804-1816 between the Drop Redoubt’s eastern face and the escarpment at the south-eastern edge of the Heights. This ditch was replaced by another on a greater scale an on a slightly different alignment; it extended to the cliff face rather than the escarpment. It had a profiled rampart and banquette on its southern side and was defended by the eastern gun rooms at the Drop Redoubt. (location accurate to the nearest 1m based on available information)