The oldest part of the defensive works is Ditch K (see map). This was investigated by Eliot Curwen in the 1930's and was found to date prior to the 6th Century B.C. when the Iron Age hill-fort was constructed (over 2,500 years ago). Holmes (1969) and Curwen both noted that this Ditch was completely silted up when the Iron Age rampart was contructed putting its date well in to the Late Bronze Age, the ditch runs under the later ramparts of the Hillfort and thus clearly predates them.. As a roughly linear ditch defending the flank of the hill which offers the best natural defense it makes little strategic sense. It may represent a part of an earlier set of defensive works, the overall plan of which has yet to be determined. Alternatively, it may have been somehow linked to the existence of the barrows, perhaps Iron Age farmers respecting and making a division between a sacred space and farmland or pasture (parallels exist for this elsewhere, such as Oakley Down in Dorset). Indeed, it has been suggested that there may be a preference for locations with existing sacred functions, like barrow groups and henges, in the siting of early Hillforts like Hollingbury (Bradley 1981).