Kisimul Castle (Scottish Gaelic: Caisteal Chiosmuil) is located on a small island off Castlebay, Barra, Outer Hebrides, Scotland (Scottish Gaelic: Bàgh a' Chaisteil, Eilean Bharraigh, Na h-Eileanan Siar, Alba). This is the former seat of the Clan MacNeil and probably dates back to the fifteenth century. Within the curtain wall of this well preserved castle are the remains of structures including a tower.