The site of the Shimizuyama Castle is a castle ruins from the Sengoku period on the west coast of Lake Biwa. This is the castle of Konoe Genji clan and Sasaki clan who ruled the area since the Kamakura period. From the center located at an altitude of about 210m, you can overlook Lake Biwa and the Azumi River basin. There are strict defensive functions remaining, such as the largest Horikiri in the prefecture and a saddle-shaped empty moat group. It was designated as a national historic site in 2004 because it is a valuable castle for learning about the leading Sengoku warrior’s life style. Omizo Castle was built in 1578 by Nobuzumi Oda who was a nephew of the famous Sengoku ruler, Nobunaga Oda. The castle was built by Mitsuhide Akechi, and it is known as Mizushiro where the water of the adjacent Otome Pond is taken into the moat. Only the stone walls of the castle tower still remain in the castle ruins, and the stone walls and moats of Honmaru have been reclaimed. However recent excavations have gradually revealed the appearance of the castle. Omizo castle ruins have been selected as an important component of the city-designated historic site and the important cultural landscape “Omizo waterside landscape”.