Hillforts are one of the best known, and certainly the largest, monuments of the later prehistoric period in Ireland. Their immense size testifies to the significance these central places held in economic, political and ideological terms for societies of the later Bronze Age. Hillforts were centres for high-status residence, ceremony and assembly, and a visual expression of power in the landscape. Their occurrence is another manifestation of a warrior culture that spread across Europe during the later second millennium BC. This paper presents the results of a recent investigation of hillfort chronology in Ireland. The first examples were built c.1400–1200 BC during the Middle Bronze Age, and in significant numbers during the twelfth and eleventh centuries BC into the Late Bronze Age. The possibility of hillforts dating to other periods of Irish prehistory is also considered in relation to hill-top enclosures of the Early Neolithic and Iron Age.