Biržai

Biržai lies in northern Lithuania near the Agluona and Apaščia rivers. The town first appears in writing in 1455, but its distinctive form emerged during the late sixteenth century. Around 1575 a dam at the two rivers' confluence created Lake Širvėna, intended to protect the castle from the north and regarded as Lithuania's oldest known artificial lake.

Work on Biržai Castle began in 1586, and Magdeburg rights followed in 1589. The Radziwiłł family made the town a centre of the Protestant Reformation, supporting a church and school. A Jewish community settled in the duchy at the end of the sixteenth century, while Lipka Tatars served the family. During the Swedish wars the castle was attacked and rebuilt; it was destroyed again in 1704 and remained in ruins for centuries.