Cheshire was a compact lordship along the northern part of the medieval Welsh border, where the late eleventh-century county borders were more extensive than they are today. This is evidenced in Great Domesday Book, which shows that Cheshire included the semi-detached entity of a likely separate administration represented by modern Flintshire and part of Denbighshire in north-east Wales; both modern counties are situated west of the river Dee and the Anglo-Norman Cheshire earls' honorial seat at Chester. Notably, it was in these medieval northern English/Welsh Borderlands of this north-east Wales area where the Cheshire earls and their tenants built approximately half of the entire county's castles (twenty-one definite and possible fortifications), dating from the late eleventh century onwards. The geographical focus of this article will be the northern English/Welsh Borderlands west of the river Dee.
Rachel E Swallow (Thu,) studied this question.