Hill forts are what archaeologists call single households, elite residences, whole villages, or urban settlements built on the tops of hills and/or with defensive structures such as enclosures, moats, or ramparts--not all "hill forts" were built on hills. Although best known in Europe, similar structures are found throughout the world and throughout time, as you might imagine, since we humans are at times a fearful, violent race.
The first fortified residences date to the Neolithic period, although they are not normally called 'hill forts', where defensive structures are found at such sites as Podgoritsa (Bulgaria) and Berry au Bac (France). Many hill forts appeared at the end of the late Bronze Age and beginning of the early Iron Age, around 1100-1300 BC, when people lived in small separate communities with differing levels of wealth and status. Trade throughout Europe was established and some individuals were buried in graves with lots of fancy, imported goods; differential wealth and status may well have been one of the reasons for the building of defensive structures.
Hill Fort Construction
Hill forts were constructed by the addition of ditches and timber palisades, stone- and earth-filled wooden frames or cobble stone structures such as towers, walls and ramparts. As trade expanded and luxury items from the Mediterranean became available to the growing elite classes of Europe, hill forts grew in size and complexity. By Roman times, hill forts (called oppida) were spread throughout the Mediterranean region.
Sources
Harding, Anthony. 1998. Reformation in Barbarian Europe, 1300-600 BC. pp 304-335 In Prehistoric Europe: An Illustrated History, Barry Cunliffe, ed. Oxford University Press, Oxford.
Champion, Timothy. 1996. Hill forts. pp. 277-279 in The Oxford Companion to Archaeology, Brian Fagan, ed. Oxford University Press, Osford.
