The Imori moat was once an outer moat surrounding the southwest part of Kanazawa Castle. In 1907, however, the upper part of the moat was flattened and the moat reclaimed by the Imperial Japanese Army. The site then served as army land, and, after World War II, as tennis courts.
During the Edo period, the moat spanned some 40 meters at its widest portions, had a depth of more than 10 meters, and was filled with water. Its tamped slopes inclined at a relatively gentle gradient, and the stone walls of the Riko Yaguradai watchtower rose to form its southeastern limit.
The Riko Yaguradai watchtower has stone walls of well-ordered rubble masonry, largely unchanged in appearance since the walls were renovated in 1664. The watchtower had a height of about 14.4 meters before its top part was demolished in 1907, when the Imori moat was also filled in.
After the tennis courts were moved, an archaeological investigation examined buried cultural property at the site. Lasting from 2003 to 2004, and including excavation of the bottom of the moat and research into the watchtower, the investigation revealed the basic form of the Imori moat.
The project staff formulated the restoration plans using the results of the investigation, while receiving guidance and advice from the Expert Committee on the Restoration of the Kahoku-mon Gate and Other Structures of Kanazawa Castle. The moat and the Riko Yaguradai watchtower were then restored. The restoration area lay within the boundaries of Kanazawa Castle Park, extending up to the municipal road.
Water was drawn to the moat from the Tatsumi Waterway running through Kenrokuen Garden. The water depth of the moat is about the same as that of old (approx. 1.5 meters).
The Riko Yaguradai watchtower was restored using approximately 900 pieces of stone, of which about 250 prioritized pieces were those that had been excavated during the archaeological research. The other pieces were made of Tomuro stone from inside the prefecture.