Hillforts are fortified enclosures built of earth, timber or stone and frequently sited on defensible hilltops. They were built from the Late Bronze Age, throughout the Iron Age (1100BC-AD50) and some were also occupied during Romano-British times. They enclose areas of between 0.1 and 80 hectares, although in Wales most are under 2 hectares in area.
Hillfort defences usually consist of a bank (rampart) made of material dug from an outer ditch. Some hillforts were provided with additional defences. Many hillforts have elaborate and strengthened entrances incorporating impressive gate structures.
Relatively few hillforts have been the focus of recent and extensive archeological excavations. However, evidence shows that forts contained timber or stone buildings. These include round and rectangular houses, granaries, watchtowers and shrines. Sometimes ponds or water cisterns, pits, and iron or bronze smelting hearths are also found.
There are over 1000 monuments that could be termed Iron Age hillforts in Wales, although many of the smaller ones are better described as defended farms. Some are visible on the ground as earthworks, whilst others only show up from the air as marks within fields. There is a concentration of large hillforts in the Welsh borders. By contrast, the mountainous interior has few examples. In west Wales, there are many small hillforts or defended farms. In the north-west, the common building material was stone. Here the ramparts remain well preserved.
Welsh hillforts are extremely varied in shape and location, as well as in size. Promontary forts rely upon natural defence around their perimeter. In land they may be located on steeply sided spurs, whilst on the coasts by sea cliffs. Some hillforts are located on hillslopes, which are clearly poorly suited for defence.
What roles did hillforts play within Iron Age societies? It's natural to assume that the purpose of the fort was defensive, providing protection from attack during raiding and warfare.
Some have argued that hillforts were permanently occupied settlements of chieftains with their entourages and skilled craftsmen. They may have controlled the agricultural surpluses generated by the communities that they ruled over. Others have argued that hillforts were occasional and temporary refuges for communities during times of conflict, after which, people returned to their farms in the surrounding area.
More recently, a number of archaeologists have emphasised the great diversity in hillfort characteristics. They argue for a number of different roles, not merely defensive ones. Many hillforts are sited in poorly defensive locations, others do not seem to have been lived in continuously or intensively. Instead, they may have acted as stock enclosures, agricultural fair grounds and religious centres at certain times of the year. As monuments, they may have been as much about displaying the status and power of different community groups, as they were about defence. A large number of small hillforts in Wales should essentially be seen as single farms occupied by small family groups.