This imposing limestone formation, rising approximately 35 feet above the surrounding landscape, once served as one of the seats of the King of Cashel. Local tradition differs on the rock’s name; whilst some called it Grange Rock, the inhabitants of the area knew it as Carraig A Mhéara. The castle’s strategic position on this natural fortress made it a significant stronghold in medieval Limerick.

By 1840, the castle lay in considerable ruin, its walls severely damaged and partially collapsed. The structure originally measured about 40 feet in length and 30 feet in width, with walls constructed from small grouted limestone blocks reaching an impressive thickness of six and a half feet. Only the western wall remained standing to any significant height, reaching about ten feet, whilst fragments of the other walls had largely crumbled. The stones from this once formidable fortress found new life in the construction of Raheen House, built 460 metres to the southwest, though that too had fallen to ruins by 1838 according to Ordnance Survey maps.

Historical records trace the castle’s significance back to 1186, when it formed part of the granges of Magio monastery. These granges included several important holdings: Nahava, Coracoimgillain, Naglochmib, Cathercornii, Loc Geir, Camuis and Imlevi. By 1348, the Abbot of Magio was accounting for revenues from Grangehawe whilst the lands were held by the crown following the attainder of Maurice, Earl of Desmond. The castle continued to appear in various records through the centuries, known by different names including Graunsha de Lough in 1583 and simply Grangew when it passed to Lord Bath’s ownership in 1655.