遺址[ishi] (historic) ruins
旧址[kyuushi] historic ruins
故址[koshi] historic ruins

城址[jouseki] castle site
古窯址[koyoushi] ruins of old kilns

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