The beginnings of the castle date back to the end of the 13th century, as we know from the act of the second trial of the bishop of Kraków, Jan Muskata, filed in 1306 by the archbishop of Gniezno, Jakub Świnka. It was then described as a castle in Przemiłowice. The new name of the castle, Olsztyn appeared only in 1341. The first mention about castle’s burgrave, Zbyszko, dates back to 1349. Since the beginning of its existence, the stronghold was to protect the western boundaries of the Kingdom of Poland against invasions from Silesia and the Czech Kingdom. It also served as a royal prison. According to tradition, during the reign of Casimir the Great, voivode of Poznań, Maćko Borkowic was imprisoned in it, who had been sentenced to starvation for organizing a plot against the king.
In 1370, king Ludwik Węgierski transferred Olsztyn to Wieluń land in the fiefdom of the Opole prince Władysław Opolczyk for supporting his dynastic plans. In 1391, king Władysław Jagiełło, after a three-day siege, captured the castle and restored it to the Polish Crown. Later, the Olsztyn goods obtained the status of a starosty, granted to the most meritorious families of the Kingdom. The first tenutary was Jan Szczekocki of the Odrowąż coat of arms, followed by his son and grandson.
In the fifteenth century, the so-called lower castle was created, which was probably expanded in the next century. Further renovation and modernization works were carried out in the 16th century by the starost Mikołaj Szydłowiecki and his successor Piotr Opaliński. In 1587, the castle was ineffectively besieged by archduke Maximilian. In 1656, the Swedes devastated castle and it remained in ruins. From 1722 the demolition of walls began, and the building material was used to erect the church.
The castle in its developed form consisted of several parts: the upper, middle and lower castle as well as two outer wards. The oldest upper castle was built from the local limestone at the top of a rocky hill. It consisted of a perimeter wall on the projection of a quadrilateral and a cylindrical tower with a diameter of 8 m and a height of 20 m. Next to it was a brick, circular water cistern. The courtyard from the north was ended by a residential house. The entrance led through the gate at the tower. Probably at the same time the middle castle was created, acting as an economic base. At the beginning of the 16th century, the lower castle was separated and two economic wards were created, surrounded by walls and moats. Then probably the main tower of the castle was raised to 26 meters.
To this day, the walls of the residential part, cylindrical main tower and square tower known as Starościa or Sołtysia, fragments of walls of economic buildings and partly cellars have survived. Today, the stronghold is owned by the local community, which collects a small fee at the entrance to the castle and at the viewpoint in the Sołtysia tower.
Leksykon zamków w Polsce, L.Kajzer, S.Kołodziejski, J.Salm, Warszawa 2003.