The North Entrance to the Western Heights was situated at a narrow point of the ridge towards the north-eastern end of the fortress, where the North Military Road completed its more moderate ascent from Dover town. The earliest phase of works on this entrance dates to the Napoleonic period, it was located at the top of a slight combe, which was flanked by the North Centre Bastion on the west and by the North-East Flank of the Lines on the east. Further work on the North Entrance began in in March 1860 and it was completed in February 1864 this created a more elaborate defensive scheme and perhaps reflects a greater concern with a potential assault from the north. A major aspect of the 1860s improvements was the twin ditches and the tenaille which were connected at the north-eastern end to the North Lines and at the south western end, to the ditch surrounding the North Centre Bastion. (location accurate to the nearest 1m based on available information)