Granuaile's Castle is a tower house and National Monument located in Clare Island, Ireland.

[2][3] Granuaile's Castle was built in the 16th century by the Ó Máille (O'Malley), Kings of Umaill.

It was a stronghold of Gráinne Ní Mháille (Grace O'Malley, c. 1530 – c. 1603), the famous "pirate queen."

[4] In the 1820s the castle was converted into a police barracks, when the purple slate flashing was added to the two bartizans.

[citation needed] The main living room was at that first floor level with access to the bartizans and the garderobe.