Large multivallate hillforts are fortified enclosures, located on hills, and are defined by 2 or more lines of concentric earthworks, which demarcate an internal area of between 5ha and 85ha. On the majority of sites these earthworks will be closely spaced, at intervals of up to 15m. Examples have been recorded where the spacing between the earthworks is wider, either for all or part of the circuit.
Each earthwork usually comprises a rampart accompanied by a ditch, although some are formed by ramparts alone. These multiple boundaries will describe a complete circuit, except on sites situated adjacent to a particularly steep slope or precipice. In examples of this nature, the largest and greatest number of earthworks will occupy the gentlest slope. They tend to continue in reduced or univallate form along the steepest part of the hill, and on some sites are entirely absent in this area.
Most large multivallate hillforts have two entrances, although examples with one and more have been noted. These may be marked by simple gaps; inturned ramparts; offset ramparts; oblique approaches; guardrooms; hornworks; and outworks.
The majority of excavated and surveyed sites have produced evidence for intensive occupation. The main building form comprises oval or circular houses, constructed in a variety of materials, which in many cases appear to have been rebuilt on a number of occasions. These show a considerable variation in diameter and a tendency to cluster in specific areas. Some seem to be aligned along streets. They may be associated with annexes, or located within palisaded enclosures. Four- and six-post structures, interpreted as raised granaries, are also fairly common. A small number of sites include buildings which appear to have functioned as temples. Other features comprise platforms; paved areas; pits; gullies; fencelines of stakes or posts; hearths; and ovens. There is evidence for bronze and iron working, and potting on a number of sites. At the same time the range of finds may include artefacts from well outside the immediate locality.
It might be possible to confuse large multivallate hillforts with univallate forms if the outer earthworks have been levelled. The problem can usually be resolved by careful survey, which should, at least, result in the identification of ditches. A second source of confusion may lie in the distinction between large multivallate hillforts, where earthworks are separated by distances exceeding 15m, and multiple enclosure forts. This is likely to occur mainly in south-west England, where the distributions overlap. Distinctions between the two classes are relatively numerous and include differences in size, topographic location and the scale of the earthworks. Unlike large multivallate hillforts, most multiple enclosure forts are smaller than 5ha and tend to be located on hillslopes rather than hilltops. The scale of the earthworks, surrounding the inner enclosure on large multivallate hillforts, will be much greater than on multiple enclosure forts. In addition, widely spaced earthworks on large multivallate hillforts usually occur in conjunction with closely spaced ramparts.
Large multivallate hillforts are usually seen as centres of permanent occupation, and it has been suggested that some represent proto-urban settlements. Many interpretations stress the defensive nature of the earthworks and represent their construction as a response to increasing warfare. In recent years, this emphasis has changed, and large multivallate hillforts are seen as one manifestation of the power struggles between competing elites. Their ability to mobilise the labour, necessary for monumental works on such an enormous scale, is seen as the ultimate expression of this competition.