A sister castle or twin castle relationship is the castle equivalent of sister city, between two geographically distinct castles, usually by agreement between two local governments famous for castles.<br> Some Japanese castles establish sister relationships with not only domestic castles but also European castles.
On 26 March 2015, Conwy Castle in Wales was twinned with Himeji Castle. Both castles are World Heritage Sites.
The term friendship castle alliance (Ã¥ÂÂ好åÂÂéÂÂ) is also used, but it is distinguished from sister castle(å§Â妹åÂÂ) like the examples of Himeji Castle and Osaka castle.