In 1277 Edward I launched a final invasion of the remaining native Welsh strongholds in North Wales, intending to establish his rule over the region on a permanent basis. As part of this occupation he instructed his leading nobles to construct eight new castles across the region; Aberystwyth and Builth in mid-Wales and Beaumaris, Conwy, Caernarfon, Flint, Harlech and Rhuddlan Castle in North Wales. Historian R. Allen Brown has described these as "amongst the finest achievements of medieval military architecture England and Wales". The castles varied in design but were typically characterised by powerful mural towers along the castle walls, with multiple, over-lapping firing points and large and extremely well defended barbicans. The castles were intended to be used by the king when in the region and included extensive high-status accommodation. Edward also established various new English towns, and in several cases the new castles were designed to be used alongside the fortified town walls as part of an integrated defence. Historian Richard Morris has suggested that "the impression is firmly given of an elite group of men-of-war, long-standing comrades in arms of the king, indulging in an orgy of military architectural expression on an almost unlimited budget".