Castles with keeps and outside walls composed of stone were built in the eleventh century, but since the construction of stone castles was time-consuming (several years) and expensive, they were mainly built by kings or nobles, and wooden castles remained in local regions.
11世紀には、天守や外壁が石造りの城が建築されるようになるが、石造りの城は建造に長期間(数年)かかり費用も高額になるため、王や大貴族による建設が中心であり、地方では木造の城も多く残っていた。