Carlow Castle was probably built around 1180 by Hugh de Lacy. The building was erected on a small rock-like island on the River Barrow and surrounding marsh and it served to protect the river crossings as well as the town. The name of the town is likely to derive from the place where the castle is located (Carlow, Ceatharlough – a stone on the lake). In the 12th century, a wooden tower (motte) originally stood there being a typical knight residence in those times.
The original keep was a rectangular block with cylindrical corner towers and it was one of the biggest Norman fortresses in the British Isles and Ireland. It appears to have been directly inspired by Norman castles in western France, notably Nemours (Seine-et-Marne). The entrance lies in the north wall and access to all storeys was by way of stairways in the west wall.
The castle has been owned by many – from John de Clahul (for whom it was built) who lost it to William Marshall, Duke of Leinster. In the middle of the 13th century, Roger Bigod, Duke of Norfolk came into ownership of the castle.
In 1814, new owner Dr Middleton blew up most of the walls with the intention to convert the building into a lunatic asylum.
The present remains are the west wall with two of its cylindrical corner towers.
