茨城県[ibarakiken] Ibaraki prefecture (Kantou area)
王城[oujou] royal castle
下城[gejou] withdrawing from the castle
牙城[gajou] stronghold (esp. of an enemy or opponent)
開城[kaijou] capitulation (of fort)

宮城[kyuujou] Imperial Palace
宮城県[miyagiken] Miyagi prefecture (Tohoku area)
傾城[keisei] beauty
堅城[kenjou] strong fortress
古城[kojou] old castle

一郭[ikkaku] one block
外郭[gaikaku] outer wall (e.g. castle)
外郭団体[gaikakudantai] auxiliary organization
郭公[kakkou] common cuckoo (Cuculus canorus)
胸郭[kyoukaku] chest

五稜郭[goryoukaku] five-sided fortification
城郭[joukaku] fortress
郭公[hototogisu] lesser cuckoo (Cuculus poliocephalus)
遊郭[yuukaku] red light district
輪郭[rinkaku] contour