Carlow Castle - Medieval Stronghold on the River Barrow
This castle was built in the early 13th century by William Marshal, who succeeded Strongbow (the Norman conqueror of Leinster) as Lord of Leinster. Sited on a small island at the confluence of the rivers Barrow and Burren the castle protected the river crossing and the town of Carlow. The castle was surrounded on three sides by water while an area of marshland restricted access from the fourth side.

The stone castle was not the first Anglo-Norman castle on this site. Excavations in the 1990s revealed there was an earlier earth and timber fortification. It is believed that Hugh de Lacy as 'Keeper of Ireland' built this earthwork castle c.1180AD.

The stone castle was a rectangular block containing the castle's principal rooms, protected by cylindrical towers corners. This design is rare among castles in Ireland, it may have been copied from western France, an area also under Norman control. The walls were 2.7 metres thick and the excavation revealed that the castle has no foundations. The original building was two storeys high with a third added later. The entrance to the castle (still visible) was at first floor level near the north-west tower.

In th late 14th century the Exchequer and the Court of Common Pleas were moved from Dublin to Calow town thus making Carlow the administration Capital of Ireland from (1361 - 1363 and from 1364 - 1394).The castle and defences were significantly upgraded and it is said that £500 was spent walling th town.

In 1814AD Dr. Middleton leased the castle and in an attempt to convert parts of it for use as a lunatic asylum he accidently blew up a substantial part of the castle leaving only the west wall and its adjoining towers.