Completed in 1622, this diminutive castle of the Ii family of daimyō (domain lords) is rightly considered a National Treasure; much of it remains in its original state. Two unusual features are the teppōzama and yazama, outlets for shooting guns and arrows, designed to be invisible from the outside until they're popped out for use. Upper storeys have great views across Biwa-ko.
The castle is a 10-minute walk up the street from the station (take a left before the shrine, then a quick right, or walk through the shrine grounds).
From the castle grounds you can continue directly to the garden Genkyū-en. The path is tricky to find; look for signs in Japanese or ask for directions.