The castle at Offerlane, as it was known in medieval times, was once a significant stronghold in the far north of Ossory. In 1290, Gilbert de Clare, Earl of Gloucester, surrendered this castle along with Kilkenny to King Edward I, only to receive them back as a regrant the following month. By 1306, the manor attached to the castle was valued at £26 6s 6d per annum, a considerable sum that reflected its importance in the region.

The castle’s strategic location on what was termed a ‘strong march’, essentially a frontier zone, proved both its strength and weakness. By 1307, following the death of Earl Gilbert, an extent of his widow Joan’s possessions revealed that whilst the castle still controlled 29 carucates and 60 acres of land, the ongoing conflicts with the Irish had left these lands waste and unprofitable. The Crown was spending £40 yearly just to maintain a garrison there. Thomas de Cantewelle served as constable in 1309, holding the fortress for the king, but the castle’s military significance gradually waned. Its final destruction came in 1600 when Teige Fitzpatrick burnt it down, ending over three centuries of Anglo-Norman presence at this site.

Today, visitors can explore the substantial remains of the bawn wall, which encloses an irregular area measuring roughly 114 metres north to south and 147 metres east to west. The wall, standing between three and four metres high externally, retains some original features including a narrow doorway at the northwest angle that leads to a mural passage. From here, you can access what remains of a circular angle tower and a square mural tower. Though much of the wall has been rebuilt or refaced, particularly during restoration work around 2000, the northwest corner and parts of the western face appear to be original medieval masonry, complete with a three-metre-high base batter. Castletown National School was built within the bawn in 1951, and a water pump north of the school may mark the location of a medieval well that once served the castle garrison.