A rectangular tower house with a barrel vault (a vault arched structure of monastery) forming a ceiling or roof. The barrel consists of a semi cylinder shaped roof at the top of the third storey.
There is a well preserved fireplace in the second storey, and a turret stair leading to the roof. The castle was built in the early 15th century. The English and O’Toole defeated the Fitzgeralds here in a battle in 1547.
Two other castles, one nearby and the other on the opposite bank of the River Liffey, are reputed to have stood in the area.
Situated almost 5 km north-east of Blessington is the 14th – century keep of the castle.