Excavations by the CAER team in 2014 and 2015 have revealed evidence of a large Neolithic causewayed enclosure built on the hill and underlying the Iron Age hillfort.
Dating to the early Neolithic, when people first started to settle down and farm the land, causewayed enclosures are an extremely rare type of monument. Around 70 are known in England, but only two others (Banc Du, Pembrokeshre, and Womaston, Powys) have been confirmed in Wales. These monuments are named after the type of the boundary marking the edge of the enclosure – a ditch – which is not continuous, but actually made up of elongated pits separated by causeways of intact ground. They represent the earliest form of enclosure of open space found in Britain.
Enclosing an area of over 3 hectares, Caerau’s Neolithic causewayed enclosure is defined by at least five lines of boundary ditch. Contained within the ditches are large quantities of Neolithic pottery, flint tools and polished stone axes. The enclosure was unlikely to have been a settlement, but rather a meeting place where some of the first farmers of Wales would gather together periodically to establish community relationships through a range of activities including feasting, exchange and the performance of rituals, almost like a prehistoric Royal Welsh Show.