It is on a small island on Lough Derg on the River Shannon, it is connected to the shore of Bealkelly by a man-made causeway.
[1] It was built by the McNamaras about 1540, severely damaged in 1827, but is now restored although public access is not permitted to the castle.
[2] Castlebawn was built by Owen McNamara during an unknown year in the 16th century.
[citation needed] In 1820 it became a den for illicit poitín makers[1] and in 1827 the authorities besieged the towerhouse to drive the occupants out.
[2][3] In 1929 the construction of the Ardnacrusha power plant caused the water level in Lough Derg to rise significantly shrinking the island on which the towerhouse stands.