The main period of hillfort building occurred in the sixth and fifth centuries b. c. in southern Britain, as at Danebury and Maiden Castle (Haselgrove 1999: 120-1). The traditional understanding of these sites as defensive settlements at the top of the settlement hierarchy is now being questioned with greater frequency (e. g., Haselgrove 1992; J. D. Hill 1995a). They seem to have been part of a much larger and complex range of sites.
In the second and first centuries b. c., another form of earthwork site appears, mainly in southern England, which is called the oppidum. There has been much discussion about the function and nature of oppida and their role within the wider settlement pattern (e. g., G. Woolf 1993). The term oppidum, from the Latin for 'town’, was used by Julius Caesar in the Bellum Gallicum to describe the late Iron Age sites that he saw in Gaul. By labelling these sites as oppida he was interpreting them through his own elite Roman mindset.52 The use of the term to identify these sites within archaeology has contributed towards the traditional notion of late Iron Age oppida as meaning primitive forms of urban settlement. These were then replaced, in the classical and modern mind, through an act of progression, by Roman forms of urbanism. However, our understanding of these sites is still very basic and this in turn has led to a simplistic understanding of the process of urbanisation. The earthworks and dykes have traditionally been interpreted as defences (e. g., Boon 1974: 42; Fulford 1984:288; Hawkes and Hull 1947:45). The fact that they do not easily enclose areas, however, and are often extensive in length indicates their impracticability for defence and argues for more symbolic functions (Haselgrove and Moore 2007b: 6). There were motives other than those of practicality behind the decisions made to locate activity at these places.
Oppida have been grouped into two types, 'enclosed’ and ‘territorial’, with the ‘enclosed oppida’, including Oram’s Arbour in Winchester, Salmonsbury in Gloucestershire, and Bigbury in Kent, appearing first (Haselgrove 1999: 121). They seem to have a definite earthwork enclosure as opposed to the ‘territorial oppida’, which consist of discontinuous earthworks covering large areas of land and often apparently containing more than one focus, such as Verulamium (St Albans) and Camulodunum (Colchester); it is often not clear what the earthworks were attempting to demarcate or define (Haselgrove and Moore 2007b: 6). It might be that this was symbolic of places that were focal points where people came together (Sharples 2010:173). The names 'Verlamion’ and 'Camulodunon’ are often used to distinguish the Iron Age period settlements from the Roman towns. These have been reconstructed from lettering on Iron Age coinage, although the exact names and spellings are still uncertain (Potter 2002: 21). These two names will be used for the Iron Age settlements here so as to avoid confusion with the Roman towns that followed.
Oppida and hillforts comprised only a small proportion of the large variety of settlement types across Iron Age Britain, and they themselves were probably parts of larger complexes of different enclosed and open sites (cf. Moore 2006). Many Roman towns have traces of pre-Roman activity that do not fall within the traditional oppidum category. Lincoln, for example, has some evidence of earthworks, and sites without any traces of earthworks could also have represented important places in the landscape. Other late Iron Age settlement types include a wide range of farmsteads and open settlements and a number of shrines. Other types of religious sites, including natural places (cf. Bradley 2000; Derks 1998), have been neglected, affecting our understanding of many of the places preceding Roman towns in Britain. It may be that the Romans chose to locate forts and develop towns at places that were already socially significant within indigenous society, perhaps being religious and meeting places (Creighton 2001). Even though practical considerations were important, the nature of the Roman settlements may been influenced by the meanings attached to these places. Establishing the significance of these sites will provide some information as to how the creation of Roman urbanism was conceptualised. This will aid in our understanding of the long-term biography of towns.