Gleninagh Castle was the stronghold of the O'Loughlin family, who owned and lived in this castle from the 16th Century up until 1840AD. The distinctive L-shape of the castle allowed the main entrance to be defended by protective walls and the box machicolation, high above it, from which stones or burning objects could be dropped on attackers. The four storied castle also shows arrow-slit windows within the tower walls for additional protection.