Biržai Castle is an earth bastion-type castle. The construction started in 1586 by the order of Krzysztof Mikołaj Radziwiłł. In 1575, preparing for this construction, a dam was built on the Agluona and Apaščia rivers at their confluence, and the artificial Lake Širvėna, covering about 40 km², was created. Major castle building works were finished in 1589.
Since the second half of the 17th century, the castle has been the main seat of the Biržai-Dubingiai Radziwiłł family line, which was transferred here from the Dubingiai Castle. Biržai Castle served as a major defensive structure during the wars with Sweden.
The castle was reconstructed from ruins in the 1980s, in the Renaissance-Baroque style. The residential manor of the castle houses a library and a regional history museum 'Sėla' (literally Selonia), founded in 1928.
References:The Château du Lude is one of the many great châteaux of the Loire Valley in France. Le Lude is the most northerly château of the Loire Valley and one of the last important historic castles in France, still inhabited by the same family for the last 260 years. The château is testimony to four centuries of French architecture, as a stronghold transformed into an elegant house during the Renaissance and the 18th century. The monument is located in the valley of Le Loir. Its gardens have evolved throughout the centuries.