Azuchi Castle

Azuchi Castle was a mountain castle located in Azuchi Town, Ōmihachiman City, Shiga Prefecture, Japan, built on Mount Azuchi along the eastern shore of Lake Biwa. The castle was constructed by Oda Nobunaga in the late Sengoku period as a key symbol of his vision of “Tenka Fubu” (unifying the realm through military force) and is regarded as one of the pioneers of early modern Japanese castles.

Construction of Azuchi Castle began in 1576 (Tenshō 4), with its location strategically chosen. Mount Azuchi, close to Kyoto and situated along major routes to Hokuriku and the Kansai region, offered convenient access by both land and water, making it an ideal military and political center. The design of the castle broke away from tradition, featuring for the first time an enormous six-story tenshu (main keep, locally called “tenshu”), which incorporated elements of Chinese, Buddhist, and Japanese architectural styles.

The scale of the structure was unprecedented. Records describe the keep as six stories above ground with one underground level, reaching a height of around 32 meters—an exceptionally tall building for its time. Within the castle grounds were Nobunaga’s residence, as well as the estates of his family and top retainers, including Toyotomi (Hashiba) Hideyoshi and Maeda Toshiie, located on the lower slopes. The construction employed numerous master craftsmen, particularly the renowned Anō-shū stonemasons, who later played significant roles in castle building throughout Japan.

Unfortunately, after the Incident at Honnō-ji in 1582, when Nobunaga was betrayed and killed by his vassal Akechi Mitsuhide, Azuchi Castle was destroyed by fire soon afterward. The exact cause remains uncertain—some suggest it was set ablaze by the Akechi forces during retreat, while others believe Nobunaga’s son ordered its burning to prevent enemy capture. The castle was never rebuilt and eventually abandoned.

Today, the Azuchi Castle ruins are designated as a National Special Historic Site and form part of the Biwako Quasi-National Park’s special protection area. Though the original buildings no longer stand, the site retains impressive stone walls, the grand Otemichi (main approach), the tenshu foundation, and surviving structures such as the Niōmon Gate and three-story pagoda of Sōken-ji Temple. In recent years, extensive archaeological excavations and restorations in Shiga Prefecture have revealed the scale and layout of the Honmaru Palace, retainers’ residences, and the stairways and plazas leading to the summit.

Of special note, Shiga Prefecture is planning a major project in 2026 to mark the 450th anniversary of Azuchi Castle’s construction. This “Great Reiwa Survey” will conduct detailed archaeological and historical research on the tenshu and related structures, laying groundwork for potential future restoration or revitalization. Although no concrete reconstruction plans exist yet, these efforts are steadily bringing Azuchi Castle’s historical grandeur back into view for the public.