A large univallate hillfort is a fortified enclosure of between 1ha and 10ha, located on a hilltop, which is surrounded by a single boundary comprising earthworks of massive proportions. These may be combined with relatively slight ramparts and/or ditches placed along the line of natural features, such as cliffs; steep scarps; or rock outcrops, which form equally imposing boundaries.
Most hillforts belonging to this class are provided with one or two entrances, which often take the form of long corridors created by inturned ramparts. These are usually closed by a gate, located towards the inner end of the passageway. The entrance may be flanked by guardrooms and/or accompanied by outworks.
Excavations within large univallate hillforts usually uncover a high density of features which include postholes; stakeholes; slots; gullies; floors; pits; ovens; hearths; and roads. Reconstructed buildings comprise round-houses and small rectangular/square structures, interpreted as granaries.
Problems may arise in attempting to distinguish between large univallate hillforts and other classes of hillfort, including hilltop enclosures and slight univallate hillforts, which are also defined by a single line of earthworks. Since hilltop enclosures always exceed 10ha they are easily distinguished from large univallate hillforts, which enclose an area of between 1 and 10ha. Quite apart from this, the scale of the earthworks surrounding large univallate hillforts is much greater. This second point also provides the major distinguishing factor between large univallate and slight univallate hillforts. Fairly insubstantial earthworks do occur on some large univallate hillforts, but unlike those surrounding the slight univallate class, they are always located above a particularly steep slope or sheer face, where they serve to enhance an already difficult approach. They also occur in conjunction with massive earthworks across the gentler slopes.
Some large univallate hillforts are associated with annexes and may resemble multiple enclosure forts. Confusion can usually be resolved, since the earthworks of the main or inner enclosure on such sites are of a far larger scale than would be the case on multiple enclosure forts.
The size of the earthworks reflects the ability of certain social groups to mobilise the labour necessary for works of monumental scale. The resulting hillforts must have formed symbols of power within the landscape, while their function may have had as much to do with ostentation and display as defence. Many seem to have been permanently occupied and to have relied upon the products of agriculture and domestic animals as sources of subsistence. A number of interpretations suggest that these basic economic activities were carried out by groups living in smaller enclosures and open settlements. The hillforts are seen as centres of redistribution, not only of subsistence products, but also of items produced by craftsmen and of other exotica.