01 / Castle site
The military governor's residence on spring-fed groundwas found in an enclosure ringed by a moat.

Igawa Castle Site, part of the nationally designated Ogasawara Clan Castle Sites, lies in a spring-fed area near a river confluence. Excavation uncovered a rectangular enclosure, 100 m north to south and 70 m wide, ringed by a moat that used the Zunashi River and its old channel; in the south-east corner is a mound said to mark a turret platform.
- National Historic Site, designated 2017
- 100 m north-south, 70 m wide
- Mound said to be a turret platform

