carlow castle

The original keep was 3 storeys high and was square in shape with stout three-quarter round towers at the corners, but only the eastern half still stands, with its two corner towers and the connecting wall. The entrance was through a door on the first floor of the north side. The topmost storey of the north-western tower dates back to the 15th-16th century.
Although the castle is only first mentioned in 1231, it was probably built by William the Marshall or by his son not long after he gave a charter to the town in 1208. William's grandnephew handed it over to the Crown on his death in 1306. In 1312 it was granted to Thomas Plantagenet, surnamed 'de Brotherton', who became Earl of Norfolk, and it remained in possession of the same family until it was confiscated by the Crown in 1537 because the owners were absentee landlords. It was already in bad repair by 1307.
It was captured in 1535 by Silken Thomas, but was retaken after a short siege. It was bought by Donough, Earl of Thomond, in 1616.