Though legend claims King John built the original castle here in 1185, it was destroyed almost immediately and rebuilt shortly after. For centuries, the bishops of Lismore controlled this strategic stronghold until the turbulent Desmond Rebellion of 1579 left it severely damaged. The castle’s fortunes changed when Sir Walter Raleigh acquired it in 1590, though he soon sold it to Sir Richard Boyle, who began ambitious reconstruction work in 1621.

The castle endured a particularly rough patch during the Confederate Wars, when it was captured in 1645 and left in ruins by 1650. The second Earl of Cork managed to restore it by the late 1600s, but neglect throughout the 18th century took its toll once again. A remarkable discovery in 1814 changed everything; whilst rebuilding work was underway, workers uncovered the precious Lismore crosier and the Book of Lismore, two extraordinary medieval treasures hidden within the castle walls. Most of what visitors see today dates from this 19th century renovation, when limestone repairs, crenelations and various additions transformed the structure into the residence still used by the Duke of Devonshire.

Despite its many transformations, traces of the castle’s earlier incarnations remain. The basic ground plan follows a hollow square design from the 17th century, whilst the enclosed garden to the south, created in 1626, retains its original walls complete with defensive towers at the corners, musket loops and wall walks. The outer gateway incorporates a fascinating bit of architectural recycling; a Romanesque doorway, likely salvaged from the old St Mary’s church, now serves as part of the entrance, topped by an armorial plaque. Even an ancient ogham stone from Ballyknock in Cork found its way here, adding another layer to this site’s remarkable accumulation of Irish history.