Rosguill (Irish language and official name: Ros Goill) is a peninsula situated in north-north-west County Donegal, Ireland. Lying between the peninsulae of Fanad to the east and Horn Head to the west, Rosguill is a dichotomy of heathland and ocean. With the great Sheephaven Bay with its mellow waters and pure-white strands on the one hand, and the treacherous sand banks of Mulroy Bay on the other. Between, a mixture of bog, hill and pastureland, the ancient walls, remnants of cattle enclosures, and the various evidences of fortification are proof of the area's use since antiquity.