On the west side of the castle close to the Yahagi river, there is an interesting row of old tiled buildings where for more than 500 years, craftsmen have produced one of the most popular varieties of miso in Japan (Location).
Located near the river to make it easier to transport the soybeans and the finished product, inside these buildings are huge old cedar casks, held together by braided bamboo and with the lids held securely in place by a mountain of carefully placed large stones. The stones need to be carefully arranged so that they do not collapse during earthquakes.
Under the pile of 3 tons of rocks, the lid presses down upon 12,000 pounds of miso that slowly ferments during a process lasting more than 2 years. The finished product is immensely popular, and Hatcho Miso has been supplied to the Emperor in Tokyo since the Meiji era. There are tours available, starting every 30 minutes, and the product (good health food) is available from the door and makes a good souvenir.
Homepage: http://www.kakuq.jp/home/Default.asp (both English and Japanese)