First built by Duke Kristupas Radvila in the late 16th century, Biržai Castle was largely restored in the 1980s, having been twice destroyed. Its huge, white-washed bastions striking skywards from man-made Lake Širvėnait was the seat of the Dukes of Biržai, and found itself in the front line in two wars with Sweden. The main castle and arsenal house fairly dry exhibitions of local wildlife, ethnography, military history, and the story of the castle, the Duchy and Radvilas family.
Highlights include temporary exhibitions of contemporary art, displays of traditional women's attire and musical instruments. The atmospheric cellar restaurant, Pilies Skliautai, serves hearty renditions of traditional Lithuanian dishes.