Château de Hiei Oyama

Hiei Oyama castle sat on elevated terrain near the Omoigawa River, with main structures strategically positioned to oversee key passages through the Kanto region. The hilltop location provided command over trade routes and troop movements through the valley below.

The castle was founded in 1148 by Oyama Masamitsu, a descendant of Fujiwara Hidesato who ruled territories in Musashi Province. By 1600, it had become a venue for important political gatherings that shaped power struggles during the feudal age.

This castle served as a military hub and information exchange point along the Oshu Kaido trade route, linking the Kanto and Tohoku regions. It functioned as a communication center between distant territories during the feudal period.

Today the grounds operate as Shiroyama Park, which sits roughly ten minutes on foot from Oyama Station on the JR East line. The park setting makes it straightforward to explore the ruins and get a sense of the site's layout and position.

A major political meeting took place here in 1600 where decisions were made that significantly altered feudal power arrangements. This gathering had lasting effects on the territorial reshaping that followed years of conflict.