Nationally designated historic site Izawa Castle Ruins
Isawa Castle, built by Sakanoue Tamuramaro in Enryaku 21 (802), is a square castle surrounded by a 675-meter-long earthen wall, and many government offices, including the government office, were located within the castle. .
It has been designated as a national historic site, and as excavations progress, valuable materials have been discovered, including wooden tablets, earthenware with letters inscribed on them, as well as lacquer paper documents containing the history of the castle and the soldiers who worked at the castle.