Castle Island

Castle Island is a bare rock islet at the south-eastern corner of Lough Key in County Roscommon, long known as Mac Dermot's Rock and fought over for centuries because it symbolised Mac Dermot clan power. Every stone had to be ferried from the mainland, and the place was burned, besieged, plundered and disputed from the twelfth century onward. What stands now is a layered ruin: an older cashel beneath a tower house and later King-family fishing lodge work, with a submerged pier marking the crossing used since medieval times.