Constructed in the late 15th or early 16th century by Connor Liath O’Connor Kerry, whose father John built the nearby Lislaughtin Abbey, this impressive five-storey tower was originally an island fortress with a unique defensive system. The castle proper, measuring 9.5m by 17.8m with walls over 2 metres thick, was protected by two concentric curtain walls; the inner wall featured rounded turrets whilst the outer wall, enclosing three sides to the north, south and west, had square towers at its corners. The space between these two defensive walls served as a dock for boats, creating a fortified harbour that made Carrigafoyle particularly formidable.

The castle’s military significance became brutally apparent in 1580 when John O’Connor attempted to defend it against Elizabethan forces led by Sir William Pelham. With a garrison of 50 Irish soldiers and 19 Spaniards commanded by an Italian engineer called Julio, O’Connor thought his island fortress impregnable. However, Pelham’s forces demonstrated the devastating effectiveness of artillery warfare in Kerry for the first time, positioning cannons both on the mainland and on ships in the Shannon. After just two days of bombardment, the castle walls were breached and stormed; all defenders who survived the assault were either hanged or put to the sword. The castle changed hands several times during the turbulent years that followed, with O’Connor Kerry briefly retaking it in 1601 and slaying the English garrison, before it finally fell to Cromwellian forces in 1649.

Today, this national monument in State care still impresses visitors with its substantial remains. The tower, built from small stones neatly laid in courses, stands partially intact at 23 metres high. Whilst the inner bawn has completely disappeared, portions of the outer defensive wall survive, including a loopholed western section that’s 2 metres thick and extends 21 metres, incorporating what appears to have been a dovecote in one of the square corner turrets. The castle’s dramatic history and unique island fortress design were captured in an illustration in Pacata Hibernia, published in 1633, which shows the sophisticated defensive arrangement that once made Carrigafoyle one of Kerry’s most formidable strongholds. Following the Cromwellian destruction, the castle and much of the surrounding barony of Iraghticonnor were granted to Trinity College Dublin in 1666, ensuring its preservation as an important piece of Ireland’s medieval heritage.