The first mention of the Bolesław the Pious castle in Bolesławiec comes from 1268. We do not know its appearance, it was probably a wooden object. The border location of Bolesławiec and the threat from Silesia under Czech influence, caused in the thirties of the fourteenth century that king Casimir the Great ordered the construction of a new, brick castle. It was created among the riverside wetlands in the place of the former castrum of Bolesław the Pious. The oldest preserved fragments of the castle come from this period. At the end of the 14th century, it became the property of Władysław Opolczyk, but after the war with king Jagiełło in the years 1391 – 1401 it was conquered by the Polish army and became the seat of the starosty. In 1704, it was blown up by the Swedish army and hence served as a free quarry for the local population.
The castle was erected on high foundations of erratic stones, and the upper parts were built of bricks, combined with lime-sand mortar. Initially, it was a simple castle consisting of perimeter walls and a gatehouse, as well as a timber building on the inner courtyard. At the end of the 14th century, on the initiative of Vladislaus II of Opole, the building was expanded, erecting an octagonal main tower and adding two buildings to the eastern part of the wall. The southern one had dimensions of 10.5 x 14 meters. The perimeter walls were also raised and a latrine was added between the above buildings. One of them was destroyed during the siege by the army of king Jagiełło. The reconstruction of the castle from the 15th to the 16th century did not introduce any significant changes, only a new building was erected between the houses of Vladislaus.
The perimeter wall of the castle was 170 meters long and consisted of a few dozen simple, short fragments joined at an obtuse angle. It created a closed circuit with a plan similar to oval. The wall in the aboveground part was about 7-8 meters high and its thickness was 2.4 meters. The octagonal tower was over 22 meters high and 8 meters in diameter. A domed ceiling was used in the ground floor. The original, only entrance to it was at the height of the crown of the perimeter walls. Tower was situated deep in the courtyard, on the opposite side of the gate, as an additional protection and the final point of defense.
The main element of the castle which has survived to the present day, almost entirely, is a large, octagonal tower – bergfried. Both in the ground floor and on the first floor, entrance openings have been preserved, although the lower one was pierced in early modern times. Fragments of perimeter walls are also visible. Entrance to the ruin is free.
Leksykon zamków w Polsce, L.Kajzer, S.Kołodziejski, J.Salm, Warszawa 2003.
Poklewski-Koziełł T., Średniowieczne zamki między Prosną i Pilicą, Łódź 1992.