The bishopric of Włocławek played an important role in the Polish Church until the period of partitions, being the third most important after the archbishoprics of Gniezno and Kraków. A clerical career often led through Włocławek to important positions, such as the bishopric of Kraków or the archbishopric of Gniezno. The bishops of Włocławek were also financially powerful, paying a significant part of the annates (papal tributes) from Polish dioceses. The diocese of Włocławek was established in the 12th century and consisted of the areas of Gdańsk Pomerania and Kujawy. She had a rich estate, which was divided into table and chapter estates. The architectural foundations of the Włocławek bishops, especially defensive buildings, were less researched compared to other dioceses, but there were already studies in this field. Włocławek has been an episcopal seat since the 11th century, and the Gothic cathedral, built around 1340, still exists today. The early medieval stronghold of Włocławek was transformed into an episcopal seat, and the construction of a brick castle began after its destruction in the Polish-Teutonic war. The bishops' country manors, which were the centers of individual estates, were also expanded. The defensive architecture of the Włocławek bishops was typical of the Baltic region, and in the 16th century, late Gothic style was preferred. Episcopal palaces from the 17th century were already part of the general trend of Polish palace construction, although they cannot be treated as an element of the defense system of the Kingdom of Poland. Castles and episcopal manors were an integral part of the structure of the state of the Włocławek bishops, serving primarily their political and administrative needs, and not directly in the defense of the Kingdom of Poland.