Kanazawa Castle is the formal residence of the Maeda family, famous for being the domain Lords of 1 million Koku. Due to repeated natural disasters over the years the original massive stone walls began to suffer from a series of damaging cracks and throwing out, which posed a threat to the integrity of the structure.
The restoration work on the stone walls was carried out by replacing the damaged stones with new ones. Overall the work was a large scale rehabilitation and reconstruction project that required the restoration of approximately 3,800 stones to a maximum height of 12m spread over a total area of 1,200m2. This covered the foundations of Hishi Yagura, a rhombus turret, Gojukken Nagaya, a long row-house used as an armory, and Hashizume Mon Tsuzuki Yagura, a turret for Hashizume Gate.
The original construction method was a closely guarded secret within the Goto family, the ancestors of whom were stone masons for the Maeda family. This inherited construction method was applied to the restoration work and was used in determining the inclination pitches and the methodology for laying the stones. The critical factors in determining the stability of the stone walls are a combination of the length of the overlapping stones, the thickness of the cobble stone layers, and the condition of the surrounding soil.
The restoration work was successfully completed as a marriage of traditional construction methods and the latest technology such as laser surveying, Rayleigh-wave measurement, and the distinct element method for surveying and testing. The end results are revitalized stone walls that will last for several more centuries to come.