Omizo jinya (regional government office of the Omizo Domain) (大溝陣屋)
After Nobunaga ODA invaded Takashima County in 1572, Nobuzumi ODA governed the county, and the Omizo-jo Castle was built according to the nawabari (castle plan; general term for the layout of a castle and its component structures) developed by Mitsuhide AKECHI in 1579. When the Honnoji Incident occurred in 1582, Nobuzumi was killed in Osaka because his lawful wife was a daughter of Mitsuhide AKECHI. After Nobuzumi, the lord of the castle changed constantly from Nagahide NIWA, Mitsuyasu KATO, Chikamasa IKOMA, to Takatsugu KYOGOKU, but the castle had no lords after Takatsugu KYOGOKU was relocated to Omi Hachiman.
In 1619, Mitsunobu WAKEBE entered the Ise-Ueno Domain, Ise province, being granted 20,000 koku (the unit showing the annual yield of rice). But the domain was covered by the Ikkoku Ichijo Rei (Law of One Castle per Province) issued in Genna era, and the Omizo-jo Castle was destroyed except for its Sannomaru.
Structural remnants include the Nagaya-mon gate of the jinya built on the site of Sannomaru. Although the doors are missing, it was thoroughly reformed in 1755, and still exists today as a private house, recently it was purchased by Takashima City. It is a designated cultural property of Takashima City.