Shiwa Castle Ruins, Morioka.

“There was a gate at the centre of each side facing each of the cardinal directions, with yagura watchtowers were erected at 60-metre (200 ft) intervals. Within was a secondary palisade roughly 150 metres (490 ft) square, containing the 14 buildings making up the administrative compound. The palace compound was connected to the main south gate by a road 18 metres (59 ft) in width. From the size of the foundations of the barracks and workshops, the garrison was between 1200 and 2000 men.”