Nanzan Castle

Nanzan Castle, also known officially as Shimajiri-Ōzato Castle, is a historic Ryukyuan gusuku located in Itoman, Okinawa. Constructed in the early 14th century by the Ōzato family using local limestone and wood, it served as the political capital and largest fortress of the Nanzan kingdom from 1314 until 1429. The structure was strategically positioned on a hill overlooking a small inlet, which facilitated direct maritime trade with merchant ships while providing a defensive advantage over neighboring regions. This unique geographical setting allowed the kingdom of Nanzan to thrive economically and militarily, outlasting the northern kingdom of Hokuzan for a significant period.

The castle holds profound historical significance as the seat of the Kings of Nanzan during the Sanzan period of Okinawan history. Its independence ended in 1429 following a succession dispute after the death of King Ōzato Taromai, leading to an invasion by the rival kingdom of Chūzan. Upon its capture, the castle was demolished, marking the unification of Okinawa under Chūzan rule. Throughout the centuries, the site passed through various governing bodies, including the Ryukyu Kingdom, the Empire of Japan, and United States administrations following World War II, before returning to Japanese control in 1972.

Today, Nanzan Castle exists primarily as ruins, though the site remains open to the public. A notable aspect of its modern history occurred in the 1950s when a primary school was constructed within the inner court of the ancient fortress, blending educational use with historical preservation. While the original wooden structures and stone walls largely disappeared after the 1429 invasion and subsequent conflicts, the location stands as a testament to the region's feudal past and the strategic importance of Itoman in medieval Ryukyuan commerce and warfare.