The irregular trace of the Citadel sprawls across the gently domed top of the Heights, its longer axis aligned north-west to south-east. The ditch surrounding the main fort may be divided into four sections: the North Ditch; The Gorge Ditch (on the eastern side); the Inner South Ditch and the West Ditch. Much of the western side is similar in form to the early (late 18th century) works on the fort, while the other sides were remodelled in the early 19th century. (location accurate to the nearest 1m based on available information)