First-Floor Corridors
The Great Keep’s first floor has wide corridors to give soldiers space to move around during an attack. The western and southern corridors, which face the moat, are slightly wider to accommodate many defenders at once, since an attack was more likely to come from these directions. In order to create extra headroom for soldiers carrying long bows or muskets, the corridors are approximately 50 centimeters lower than the tatami-floored area they surround.
The walls of the corridors curve subtly inward at their centers. This unintentional feature was caused by the castle’s stone-wall foundation: the rough-hewn rocks used to build the foundation were difficult to arrange in perfect right angles. As a result, the stone foundation of the Great Keep curves slightly inward. This curve is also present in the keep’s walls, which were aligned with the foundation. Although the first and second floors of the keep appear square, two of their four corners meet at less than 90-degree angles.