During the reconstruction and modernisation of the outer defences at Dover Castle in the 18th and 19th centuries a wide terreplein was created behind the main (reconstructed) ditch for several new gun emplacements. In the northern half there are substantial earthworks protecting four expense magazines which may have been added in the 1850s. In the southern part of the terreplein are four circular concrete bases which are the sites of Second World War light anti-aircraft guns. (location accurate to the nearest 1m based on available information)