01 / Agena Castle Ruins
Stone walls ring both the outside and inside,a rare ring-type gusuku in the prefecture.

It is also called Great River Gusuku, after another name of the Tengan River that runs north of the castle. The hilltop inner enclosure holds the main and second baileys, and the outer enclosure lays walls from mid-slope. It is said to have been built around the 14th century by an Agena lord, but the date of construction is unclear.
- 1972: national Historic Site
- Walls on both outside and inside
- Said built around the 14th century
