GLEASTON, a township, in the parish of Aldingham, union of Ulverston, hundred of Lonsdale north of the Sands, county of Lancaster, 3 miles (S.E.) from Dalton. This place contains several neat houses at the foot of a rising ground; and also the mouldering ruins of Gleaston Castle, which, according to tradition, was erected by the lords of Aldingham immediately after the sea had swept away the lower part of the parish, where their original residence was fixed. The date of its erection is uncertain, but the style of the architecture, as yet to be discerned, points to the Harringtons as the founders. The area of the castle is a square, and the ruins consist chiefly of two towers, nearly perfect, on the west side, with the falling stones of a wall which connects them; there are also traces of towers on the east, on which side the greater part of the ruins are at the north-east angle: the north and south walls are almost razed to their foundations. The interior of this structure, once a place of great strength and importance, is now a browzy pasture, of uneven surface, covered in many parts with masses of stones.
Extract from: A Topographical Dictionary of England comprising the several counties, cities, boroughs, corporate and market towns, parishes, and townships..... 7th Edition, by Samuel Lewis, London, 1848.