Ōno Fortress (大野城跡 ōnojōato)is located on Mount Shioji (formerly called Mount Ōno) in the northern part of Dazaifu city in Fukuoka Prefecture, Japan. Construction began in 665 A.D. Construction began after the defeat of the combined Japanese and Baekje forces by the Tang/Silla alliance at the Battle of Baekgang in 663. Fearing an invasion from the continent, the Japanese Yamato court is thought to have ordered the construction of the fortification to help protect the Daizaifu government center. Today the ruins of about seventy buildings can be seen, including buildings once used for storehouses, temples, and kitchens. A wall surrounded this area, built partly of stone, partly of earth. Sections of the wall still exist. This area is a Special Historic Site (特別史跡)