ENIn their history, the Lithuanian Birże was an important urban center — both as an important fortress of the Grand Duchy of Lithuania, as a place for the people of the Protestant faith in Lithuania, and an important trade point between Vilnius and Riga. Because of this, the Birżes had a rather turbulent history. The beginning of the history of the city and the castle can be traced back to the fifteenth century. At that time, thanks to one of the Radziwiłł heiress, Birże was taken over by the Radziwiłł family. They gave the location privilege to the city and built a fortress. Since then, it has been an important point in stopping all enemies of the Commonwealth from the north. Because of their importance, they also became the living center of the Radziwiłł Birżańskis family branch. However, the seventeenth century brings a lot of destruction to the city, particularly affected by numerous Polish-Swedish wars. The worst events for the city were its burning and occupation of the castle in 1625 and in 1655. It caused the destruction of the city and a significant loss in the number of its inhabitants. However, the Radziwiłłs tried to rebuild this urban center. Successively ruling princes, and then supervisors issued numerous laws and supported the city so that it would come alive again. Important was also all administrative reforms in the city and privileges that Radziwiłł tried to gain for the city. Of particular interest were the numerous laws issued against the abuse of trade and the flight of merchants from the obligatory trading in the city. The Jewish minority was also numerous. Unfortunately, this caused disputes with Christian residents. The rulers were also interested in the city guilds, as they were to guarantee its development. And so they tried to publish guild’s regulations which finally happened in the 80s of the seventeenth century.Although the regulations were issued, the city was in decline. Until the end of the 18th century, when it was ruled by the Tyszkiewicz family, Birże lost completely its importance. There were many reasons for this city to decline. Although many laws were issued, there were still abuses in trade. Similarly, in spite of numerous regulations regarding defense against fire, it still haunted the Birże. However, the worst phenomenon were numerous Swedish wars. And so, after the Swedish Deluge, the city never rose again, despite the efforts of Bogusław Radziwiłł and his heirs. Keywords: the Birżan Radziwiłłs, city laws, Birże citizens.