A strong and modern castle built by Duke Kristupas Radvila in Biržai served the purpose of defending the northern border of Lithuania. The fortress was heavily destroyed by Swedes during the wars of the 17th century; the Radziwiłł (Radvila) family began to rebuild it, but finally the castle was taken by Swedes again. They burst the castle while retreating. The palace restored in late 20th century today houses Biržai Regional Museum where educational programmes are also organised.
