The castle in Bydgoszcz was founded on the initiative of king Casimir the Great, as one of the defensive points strengthening the then Polish-Teutonic border. Construction lasted from around 1343 to the turn of the 50/60 of the 14th century. After the death of the founder, in the years 1370-1377, the castle was given as a fief to his grandson, Kaźko of Słupsk. In 1409, captured by the Teutonic Knights and recovered after an eight-day siege, it required a renovation, which king Władysław Jagiełło personally supervised. After the Thirteen Years War with the Teutonic Order in 1466, the castle lost its original military significance as a border guard. The starosts working on it, did not carry out major construction works, leaving the building unchanged. Only in the years 1632-1645 the starost Jerzy Ossoliński surrounded the castle with bastion fortifications. The destruction of the stronghold took place in 1656, it was blown up by Swedish sappers. Gradually dismantled in the eighteenth and nineteenth centuries, it was treated as a source of free building material.
The castle was a four-sided building with dimensions of 40×50 meters, located on a cone-shaped island. In the late Middle Ages it consisted of two houses based on longer curtains and a third house, probably the younger one, connecting them from the west. In the northern part of the eastern curtain there was a gate, and later a four-sided gatehouse, erected in front of the wall. The three corners of the castle were reinforced by four-sided, five-storey towers, which gave the castle the character of a strong fortress.
The castle has not survived to modern times.
Leksykon zamków w Polsce, L.Kajzer, S.Kołodziejski, J.Salm, Warszawa 2003.