The history of the town is connected with the aristocratic Radvila (Radziwill) family, which kept house in Birzai from the beginning of the 16th century to 1811. K. Radvila built a castle in Birzai in 1589. Defensive ramparts were later built around the castle to protect it from cannon fire, and the entire structure was surrounded by a moat. In 1575 the Apascia and Agluona Rivers were dammed up, Lake Sirvena was formed. This lake, about 400 years old, is the oldest artificial lake in Lithuania. Now here you will have a chance to walk along the 525 m long pedestrian bridge. After K. Radvila built a castle in 1589, Birzai got the rights of Magdeburg. This meant that citizens themselves had right to solve cases in court, to have markets twice a week, and twice a year tee up 14 days-long marts. In the late 16th century, Biržai was granted a privilege forcing all merchants en route to Riga to stop first in Biržai. While the decree no longer is in effect today, tourists and passers-by are still drawn to Biržai for many other reasons.

In the early – 18th century, during the wars with Sweden, Birzai became the most important defensive outpost. However, the efforts to defend Lithuania were not successful. In 1625, King Gustav Adolf of Sweden, along with 8,000 soldiers, besieged the castle. Unable to surmount it, the enemy undermined the fortress. Convinced that it would be useless to offer resistance, the garrison of the castle surrendered. The Radvila family regained the castle in 1626, although it was so damaged by that time that it would have been senseless to try to restore it. The castle needed to be rebuilt entirely. This was finally done from 1662-1669, according to a plan drawn by a Dutchman, A. Freitag. Freitag gave the castle expressive Renaissance features and reconstructed its system ot fortification. In 1701, the castle served as the meeting place for Augustas II (King of the Polish-Lithuanian Commonwealth) and Peter l (Czar of Russia), who consequently signed a pact concerning joint-warfore against Sweden. Three years later, the castle was captured and destroyed by the Swedes.

Having lost its defensive significance Birzai gradually began to fade. At the end of the 18th century, Biržai was deprived of its town rights. The Radvila family became impoverished and, in the beginning of the 19th century, the land was given over to the aristocrat Tiškevicius (Tyszkiewicz). The new masters were not interested in the collapsed castle at all, and began to erect a new residence on the opposite side of Lake Sirvena. Thus began the formation of the Astravas ensemble. The magnificent palace, built in the middle of the 19th century, is distinctly characteristic of late Classicism. The interior decor of the palace, done in the same style as the exterior, is of particular artistic value. The palace has recently been restored, and the bronze lion sculptures near the entrance have been replaced (the originals were moved to the Kaunas Museum of War). There is also an interesting bridge and park on the premises.

Restoration of the old Birzai castle was finally completed in 1988. Now Birzai land museum and a library are located here.

Among Biržai's other architectural points of interest are its lovely churches. St. John the Baptist's Church, completed in1861, is noted for the unity of its interior and exterior forms and is mentioned in B. Kviklys' Churches of Lithuania as one of the nation's most beautiful churches. Just around the corner is another splendid piece of architecture - the Evangelical Reformed Church.

Of course, Biržai's renown does not only lie in the past. Today, Biržai is home to several nationally-known businesses. Biržai's numerous breweries, each producing unique, natural beers, rightfully earn the city the reputation of Lithuania's beer capital. Of course, Biržai boasts dozens of other shops, restaurants, cafes and accommodations, which together make Biržai a delightful spot for both the resident and the tourist.