Dungarvan Castle is composed of a polygonal shell keep, enclosed with a curtain wall, with corner and gate towers.

The 12th-century shell keep is the earliest part of the structure, with this form of keep being common in England, but rare in Ireland.

[3] The castle has been described as Anglo-Norman, and was founded in 1185 by Prince John, on the mouth of the Colligan River.

The castle was used as a barracks during the Irish Civil War, then taken by the IRA who upon leaving in August 1922, set fire to the structure.

[4] After 1987 the castle fell into disrepair again, but under the management by Dúchas was restored and now provides guided tours, an exhibition and an audio-visual show.