The curtain wall has a perimeter of 1500 feet and surrounds and an area of about 3 acres of ground. It is still intact except the section facing the river to the east, which is nearly completely destroyed. The average wall height along the inclosed interior is about 11 feet. The exterior wall is about 20 feet from the top of the present level of the former moat.
The town gate to the west, currently provides public access to the castle from the adjoining car park. The barrel vault over the entrance, is still intact as is the masonry of the chamber imediately above this level. The masonry of the upper level is partially demolished. The stonework of the portcullis is intact.
The south or Dublin Gatehouse is unique as it is the only complete example of a barbican gate to survive in Ireland. The square barbican entrance tower is positioned at the edge of the edge of the former moat and it is connected to the main tower by walls which formerly supported a drawbridge. The main tower, circular in shape is constructed as part of the curtain wall. It has an interior dimension of approxmately 27 feet(8.2m) and it contains a circular stairs built into the outer wall which formally serviced two upper chambers.