Itabashi Ward and Kanazawa City concluded a friendship city agreement in 2008, as the Kaga Clan's lower residence was located in Itabashi Ward. There is a commemorative monument in the site, modeled after the Oyama Shrine gate in Kanazawa City. From the Meiji era to the end of the war, the Itabashi Explosives Factory (Tokyo No. 2 Army Arsenal Itabashi Factory), which manufactured gunpowder, was located here, and a target used for ammunition performance tests still remains on the hillside.