Oyama Castle

Oyama Castle sits on an elevated plateau above the Omoigawa River with three nested baileys connected by wooden bridges crossing deep moats. The site functions today as Shiroyama Park and displays the original arrangement of this medieval fortification where visitors can trace the defensive system firsthand.

The fortress was built in 1148 and served as the seat of the Oyama clan until the family lost control in 1576 to the Hojo. This shift marked the end of local independence during Japan's period of regional power changes.

The grounds contain a Shinto shrine that once served as the spiritual center for the Oyama clan and gave the castle its alternate name. This religious space reflects how the ruling family integrated their power with local spiritual practices that visitors can still experience today.

The site is now a park with educational displays about local history and visible remains of the defensive works that visitors can explore at their own pace. Sturdy shoes are helpful since the grounds are uneven with several elevation changes throughout the site.

The castle's defense system used three crescent-shaped moats of different widths, with earthwork embankments built only around the two inner trenches. This varied approach reveals how builders adapted their fortification design to the actual landscape they worked with.