Carrigahowley Castle (also called Rockfleet Castle), an intact 15th-century tower off the N59, is associated with 'pirate queen' Grace O'Malley. She married her second husband, Richard an-Iarrain (impressively nicknamed 'Iron Dick' of the Burke), to gain control of this castle, and famously fought off an English attack here. Moodily set on a boggy tidal area, the castle was her principal stronghold, and in her later years she settled here permanently. The castle is currently closed for safety reasons.
The other structures of the castle have vanished. Legend says that Grace fed the rope from her ship through the hole in the south wall, tying it to her bed.