Kaneda Castle, ancient mountain fortress in Tsushima, Nagasaki Prefecture, Japan

Kaneda Castle is a fortified site on a hilltop in Tsushima, Japan, where stone ramparts wind along the ridge for a considerable distance. The walls still stand tall in several places, showing the scale of the original construction.

The fortress was raised after Japan's defeat in the Battle of Baekgang to protect the island from potential attacks coming from the Korean peninsula. Later, during the Meiji era, a coastal battery was built on the site and remained in service until the early twentieth century.

The name is read Kaneda-jō, Kanata-no-ki or Kane-no-ki, and the "ki" of the old reading is linked to the shrine at the foot of the walls, Ōkido Jinja, guardian shrine of the fortress; the shrine's name may derive from the same kido. The shrine keeps seven wide bronze spearheads said to have come from the castle hill, Yayoi-period pieces 82.6 to 89.2 cm long and a Nagasaki Prefecture cultural property since 1973.

Visitors reach the ruins after walking uphill from the trailhead, passing through wooded terrain. Exploring the full site and walking along the wall sections takes several hours and requires good stamina.

Some sections of the walls still show the original grooves and notches left behind when the stone blocks were shaped. These craft marks reveal how builders in the seventh century cut and fitted the heavy stones together.