It is one of only two 'Goryokaku' (star-shaped forts) in Japan, with the other being the more famous site in Hakodate.
The castle was built to protect the Taguchi Domain after the shogunate shifted toward Western military architectural concepts.
The central area of the star shape currently houses a local elementary school building, blending modern function with historical layout.
The original design utilized a bastion system intended to eliminate blind spots in defense.
The structure was designed to be low-profile, keeping it protected from long-range cannon fire compared to traditional high-rising Japanese castle keeps.
Tatsuokajō Castle, also known as Goryokaku, is one of only two Western-style star-shaped fortresses built in Japan during the final years of the Edo period. Constructed in 1867 for the Matsudaira clan, the fort features a distinct pentagonal earthwork layout. While the original main castle structures were dismantled in the early Meiji era, the stone walls and moats remain intact today. The site currently serves as a public park and is home to the Tatsuokajo Castle Memorial Hall. Visitors can walk the perimeter of the star-shaped earthworks, which elevated defensive capabilities against modern artillery. The site is situated within the Saku region of Nagano Prefecture, surrounded by agricultural landscapes.
From the elevated observation point along the outer embankment, which provides the best angle to capture the star geometry.
Walk the elevated path around the moat to truly appreciate the pentagonal shape of the earthworks.
Visit the small memorial hall on-site to view diagrams showing how the fort would have appeared before the original buildings were removed.
Combine this visit with a trip to the nearby rural temples for a full day of local exploration.
Do not expect to see a standing castle tower or keep, as the site primarily consists of earthworks and moats.
The outdoor grounds are accessible year-round, though the memorial hall may have seasonal closures.
Respect that the site is partially utilized by a local school; remain quiet and stay on designated public paths.
