In Gaelic, Caisteal Chiosmuil translates in to English as the ‘castle of the rock of the small bay’. It is also known the ‘Castle in the Sea’ due to its location on a rock in the bay, from which the town of Castlebay derives its name. The 15th century tower house is the seat the chief of Clan Macneil, who first came to Barra in the 11th century and it remains as the only significant surviving medieval castle in the Outer Hebrides. In 2000, the stewardship of the castle was passed to Historic Scotland.