Clare Island was the stronghold of the Pirate Queen Grace O’Malley (Granuaile), a historical figure in 16th century Irish history. Biographies of her have been written by the historian Anne Chambers. On entering Clare Island harbour visitors are struck by the large stone tower which served as Granuaile’s castle. Due to its strategic location the castle was vital in controlling the waters of Clew Bay. It was build in the 16th century and considered to be a fine example of a tower house. Inside the castle, to the left of the main entrance, is a passage in the wall with stone stairs beginning on the first floor. Access to these was most likely enabled by a wooden staircase from the ground floor. The main living area would have been on the 1st floor. In the mid 1820ies the castle was converted into a police barracks.