The castle was probably built at the same time as the town walls, perhaps around 1339. During the reign of Louis Anjou in 1382, the castle was occupied by Hungarian troops. It was to be pledged to the royal son-in-law, a candidate for the throne, Zygmunt Luxemburg. In 1383, the castle and the Hungarian troops stationed there, were besieged by the knights of the Mazovian prince Siemowit IV, who took advantage of the civil war between Grzymalit and Nałęcz families, to enter Wielkopolska. After a brief pause, the Hungarian crew capitulated on honorary conditions. During this siege, the use of firearms was recorded for the first time in Polish lands.
In the 15th century the castle was often visited by king Władysław Jagiełło, and later by king Kazimierz Jagiellończyk. From the mid-15th to the middle of the 16th century, it was a protection of the dowry of Polish queens: Zofia Holszańska, Elżbieta Rakuszanka, Bona Sforza, and was kept by the royal governors.
In early modern times it was rebuilt several times. In the seventeenth century it was destroyed by the Swedes and has not regained its glory. After a fire in 1768 the castle was almost completely demolished by the Prussians, during the construction of a prison at the site of the eastern royal palace. A granary was built at the northern house and then a mill.
The castle was located within the town walls in the north-eastern corner of the town and was a typical urban castle with a shape similar to a rectangle and dimensions of approximately 49.5 x 60.50 meters. It towered over the surroundings, because it was placed on a high scarp on the Warta River. The thickness of the brick perimeter walls was 1.8-1.85 meters, and slightly narrower wall was only the northern perimeter, which reached about 1.5 meters. From the outside, the walls were supported by regular buttresses.
The gate was placed from the town side. The main castle house, 49.75 meters long and 15 meters wide, stood by the eastern curtain, and in its corner there was a turret with toilet function. From the west side, a 3.4-meter wide porch adjoined house façade.
At the north elevation of the castle there were probably two small towers. North-east with side lengths of about 4 meters, served as a sanitary facility: it was equipped with a pointed outflow, as well as a diagonal offset at the western wall. The north-west tower, with the length of the western side, about 4 meters, was probably a gatehouse.
In the north-west corner there was a rectangular main tower with a side of about 10 meters. Its inner chamber had dimensions of about 4.5 x 6 meters. The western house had external dimensions of approximately 11 x 39.25 meters. Probably there were five rooms in the row. The southern house measured about 9.5 x 34.75 meters. It was a one-bay object, divided by probably three rooms. The remaining buildings were probably wooden. Between the castle and the Franciscan monastery there was an outer ward.
Only a heavily transformed house (primary eastern wing) in which the gothic walls are hidden, as well as the buttress in the northwest corner has survived.
Badania terenowe zamków z obszaru Wielkopolski i Polski Centralnej w XXI wieku, [w:] Gemma Gemmarum, red. Różański A., Poznań 2017.
Leksykon zamków w Polsce, L.Kajzer, S.Kołodziejski, J.Salm, Warszawa 2003.