Layout of the Castle
Matsumoto Castle consists of five structures—the Great Keep, the Inui Keep, the Roofed Passage, the Southeast Wing, and the Moon-Viewing Tower.
The Inui Keep is a separate structure that connects to the Great Keep via the Roofed Passage. This arrangement is referred to as a “linked keep.” In contrast, the Southeast Wing and the Moon-Viewing Tower are attached directly to the Great Keep, which is called a “compound keep.” Matsumoto Castle is the only castle in Japan where both layouts can be seen together.
The castle was first designated a National Treasure in 1936, under the National Treasure Preservation Act of 1929. In the designation, Matsumoto Castle was noted as a rare and early example of a linked multi-structure (renritsu) design.
Following World War II (1939–1945), the 1929 act was replaced by the Cultural Properties Preservation Act in 1950, and Matsumoto Castle was redesignated a National Treasure in 1952.
Key Features of Matsumoto Castle
(1) A Flatland Castle
Matsumoto Castle was built 590 meters above sea level, on a flat plain east of the Northern Alps. Compared to the natural defenses of earlier castles that were built in the mountains, flatland castles needed additional fortification. Matsumoto Castle was originally surrounded by three moats and encircled with an elaborate system of earthen walls and gated entrances, and samurai lived within the castle’s defenses so they could quickly respond to an attack.
(2) The Oldest Surviving Five-Story Keep
Matsumoto Castle is the oldest example of a keep with five external stories and six internal floors. Design of its three original structures (the Great Keep, the Inui Keep, and the Roofed Passage) is thought to have begun under the rule of Ishikawa Kazumasa (d. 1592), and construction was completed by his son Ishikawa Yasunaga (1554–1642).
The Ishikawa family were retainers of the powerful warlord Toyotomi Hideyoshi (1537–1598). It is said that Matsumoto Castle was one of the castles built to surround and monitor Edo Castle, which was the base of Tokugawa Ieyasu (1543–1616), one of Hideyoshi’s greatest rivals.
(3) Designed for War, Designed for Peace
The Ishikawa family built Matsumoto Castle in the late sixteenth century, during a long period of civil war. During this time, regional warlords called “daimyos” built networks of castles to monitor and control their territories.
Given the turbulent times, the three original structures of the castle were built to withstand an attack. The buildings are equipped with 115 loopholes and have 11 openings called ishi otoshi that protrude over the stone-wall foundation. These various openings allowed defenders to use bows and matchlock muskets to attack enemy forces. Aspects of the surrounding complex were also designed with matchlocks in mind: the inner moat is approximately 60 meters across, which was the greatest distance at which a matchlock would reliably pierce samurai armor. Furthermore, the walls on the first and second floors of the Great Keep were roughly 29 centimeters thick and impenetrable to musket fire.
The two newer structures, the Southeast Wing and the Moon-Viewing Tower, tell a different story. They were built when the castle was ruled by Matsudaira Naomasa (1601–1666), during the peace of the Edo period (1603–1867). The elegant vaulted ceiling and vermillion-lacquered veranda of the Moon-Viewing Tower, together with the lack of defensive features, show that the tower was instead designed for peaceful gatherings.
(4) Structural Innovations
Matsumoto Castle is built on an alluvial plain formed by the Metoba and Susuki Rivers. The soft, marshy soil of the plain made the castle difficult to erect, but its builders used innovative construction techniques to prevent the 1,000-ton Great Keep from slowly sinking into the ground.
Internal Support Structure
The internal support structure of the foundation was created using 16 posts of Japanese hemlock arranged in a four-by-four grid. Each post measured roughly 39 centimeters in diameter and 5 meters in length. The posts were connected with horizontal beams, creating a frame that helped to evenly distribute the weight of the castle across the foundation. The stone-wall foundation was built around this structure, which backfilled with soil as the construction progressed.
External Support Features
Prior to building the stone foundation, workers shored up the area that would become the base of the walls using a raftlike structure of 3-meter logs placed at intervals of roughly 50 centimeters. Additional logs were then placed on top of this structure parallel to the line of the wall, creating “pillows” to prop up the larger stones at the base. As a final measure, two rows of posts were driven vertically into the ground under the moat roughly 5 meters from the foundation. These posts were believed to act as anchors to prevent the foundation from slowly eroding.