Shiwa Castle was built in 803 by the first Shogun, Sakanoue no Tamuramaro under the order of the Emperor Kanmu. This castle is located in most northern place in Japan at that time. This castle was not just for the fortress, but also it was used as the governmental office for the region.

The size of the castle
The outer moat is 928m long for each square sides. Then, inside of the outer moat, there is 840m long wall surrounding the inner zone. The centers of the each wall had gates with keeps. Every 60m, there are also the watch towers. at the center, there was a government office. Inside of the wall, there are 1200 to 2000 households for the soldiers.

The main gate and walls are restored as it was used to be. The gate is 11m tall and 15m wide. The walls are 4.5m high and about 252m are restored.

The visitor's center is also the history museum that you can study about this ruins of this castle.