The 'Ferocious O'Flahertys' were based at this superbly preserved 16th-century fortress 4km east of Oughterard. The clan controlled the region for hundreds of years after they fought off the Normans. Today their six-storey tower house stands on a rocky outcrop overlooking Lough Corrib and has been extensively restored.
Surrounding the castle are the remains of an unusual double bawn (area surrounded by walls outside the main castle); there's also the remains of the banqueting hall and a small, now isolated watchtower with a conical roof. The River Drimneen once enclosed the castle on three sides, while today the waterway washes through a number of natural caverns and caves beneath the castle.