Hikone Castle (彦根城, Hikone-jō) is a Japanese Edo-period Japanese castle located in the city of Hikone, Shiga Prefecture, Japan. It is considered the most significant historical building in Shiga. The site has been protected as a National Historic Site since 1951. Hikone is one of only twelve castles in Japan with its original tenshu, and one of only five castles listed as a National Treasure.