A. Hamilton Thompson, Military Architecture in England During the Middle Ages
“ The castle to which it was added was surrounded by a curtain, largely of twelfth-century date,354 and contained a tower-keep and domestic buildings which appear to have been in the main of the thirteenth century. Situated at the head of a very steep hill, and flanked by two huge octagonal towers, this gatehouse is the perfection of the type which is seen, with more slender flanking towers, at Bothal and in the keep of Alnwick. The window openings towards the field are few and small: the battlements are boldly corbelled out, and machicolations of large size are left between them and the wall. ”
