The Ishiyama Hongan-ji (石山本願寺) was the primary fortress of the Ikkō-ikki, mobs of warrior monks and peasants who opposed samurai rule. It was established in 1496, at the mouth of the Yodo River, on the coast of the Seto Inland Sea. At the time, this was just outside of the remains of the ancient capital of Naniwa, in Settsu Province. In fact, recent archaeological research has determined that the temple was established atop the ruins of the old imperial palace. The city (now called Osaka) has since grown around the site, incorporating the Ishiyama (stone mountain).
Rennyo, the great revivalist of Jōdo Shinshū (Ikkō-shū), retired to the area in 1496, initiating the series of events that would end in the formation of Japan's second-largest city. Contemporary documents describing his retirement site as being on a "long slope" (大坂, Ōzaka) are the first to call the area by that name, which has changed only slightly over time to Osaka (大阪), and become Japan's second largest city. Although Rennyo sought isolation in retiring to this quiet place, he very quickly attracted a great number of devotees and followers. The tiny temple Rennyo built for his own personal devotions was expanded, and many homes and other buildings were erected to accommodate the new residents. By the time of Rennyo's death, three years later, the general shape and size of the Ishiyama Hongan-ji was already in place.