After a construction period of twenty years, Hikone Castle (Hikonejo) was completed in 1622. The hilltop castle served as the seat of the Ii daimyo (feudal lords) until the end of the feudal age in 1868.

Hikone Castle is an original castle, i.e. it survived the post feudal era without undergoing destruction and reconstruction. Besides the castle's main keep, most of the inner moats, walls, guard houses and gates also remain intact. Furthermore, parts of the castle's palace buildings have been reconstructed, giving visitors a good impression of a relatively complete Japanese feudal castle.

Hikone Castle's three storied castle keep is relatively small but displays a unique design that combines multiple different architecture styles. This is one reason why the castle has been designated a national treasure, the highest designation for cultural properties in Japan, held by only three other castles, Himejijo, Matsumotojo and Inuyamajo. By climbing the steep stairs on the inside of the castle keep to the top floor, visitors can enjoy views over the castle grounds and the city.

The approach to the hilltop castle keep is also interesting. It includes a spiral ramp onto a wooden bridge that can be easily destroyed in case of an attack. There are also several turrets which can be inspected from the inside as well as a large bell that is still rung several times per day to tell the time. A large store house and a horse stable stand near the castle's main gate.

At the base of the castle hill stands the Hikone Castle Museum whose main attraction is a partial reconstruction of the former palace buildings. The buildings, which include multiple tatami rooms, corridors and gardens, served as the government offices of the lords and have been reconstructed in the 1980s with great care according to excavations. Ordinary exhibition rooms display the clan's family treasures, including arms and armor, kimono, music instruments and documents.

Like many castles in Japan, the grounds of Hikone Castle turn into a popular cherry blossom spot in spring. Hikone's cherry trees reach full bloom usually about a week later than in nearby Kyoto around early to mid April. Not a cherry blossom spot but a place of considerable scenic beauty is Genkyuen Garden located at the base of castle, just outside of the inner moat.