This grand inn (c1928) is now a national monument for its fine woodwork. Each of its three storeys was designed by a different master carpenter; architecture buffs will love comparing the styles. A highlight is the Grand Hall on the third floor, an ocean of tatami (120 mats!) flanked by stages. An additional ¥500 will let you take a dip in its onsen baths (weekends only).
Several of the rooms house odd little museum exhibits, and there's a tearoom with river views on the ground floor.