Aoyamon is an important entranceway located on the north side of Ninomaru, Osaka Castle, and has undergone numerous rebuildings over its history. However, it was severely damaged in the Great Fire of 1868, and although it was later rebuilt by the army, it was destroyed by fire again in the Osaka Air Raid of 1945. The current Aoyamon Gate was restored by Osaka City in 1969 using remaining lumber. This gate is constructed as an independent turret gate with a turret on top, but in the Edo period, the turret part extended further along the stone wall to the northwest. Unlike the other entrances and exits in Ninomaru, the square of Aoyaguchi was a “de-masugata” (protruding outward). There used to be a water moat on the outside, and a bridge called “Tasuban-bashi,” which could be pushed in and out at will, was built over the moat. It is said that this bridge was kept retracted except for emergencies. The name “Aoya” is thought to be derived from “Aoyacho,” a temple town of the Osaka (Ishiyama) Honganji Temple that existed in this area during the Warring States Period. Aoyacho was an area where dyers gathered, and “Aoya” meant dyer. It was also known as “Konya. During the Ishiyama Honganji period, there was a temple town around the main hall, which consisted of six towns: Kitamachi, Kitamachiya, Nishimachi, Minamachiya, Shimizu-machi, and Shinyashiki, and from these parent towns, branch towns were formed, of which Aoyamachi was one.