The researchers focused on the analysis of data from the castles in Wleń, Wrocław and Legnica. The new findings were made possible by the physico-chemical, petrographic, radiocarbon and dimensional analyses of materials used in their construction.

"Until now, the popular view was that the first Silesian castles date back to the 20s of the 13th century. But since the 1980s there have been discoveries that indicated that it could have happened tens of years earlier. Our research confirms these findings - the first castles were built there in the second half of the twelfth century" - explained the research project leader, Prof. Małgorzata Chorowska from the Faculty of Architecture, Wroclaw University of Technology.

The concept of conversion of wood and earthen fortified settlements into castles spread from Silesia across Poland, but it was a multi-stage process, extended in time - noted the researcher. According to the findings of the team of scientists, the first castle in Silesia was the one built in Wleń, followed by the castles in Wrocław and then Legnica.

Until now, archaeologists and architects had to trust historians and written sources with regard to the construction of the first castles in Silesia. There were now archaeological data from the analysis of the castles themselves.

The researchers studied materials including mortar and bricks, using petrographic and mineralogical analysis. They determined their composition and were able to compare the techniques of building castles in several centres.

"Until now, this was done by observing the differences perceived in the walls +with the naked eye+. But these methods were not fully objective and scientifically verifiable" - added Prof. Chorowska.

Researchers also made innovative measurements of bricks, using the method developed by Mariusz Caban, a PhD student at Wroclaw University of Technology. This method is based primarily on the collection of a large number of dimensions (up to 360) in a paired manner, or recording the dimensions of the head and stretch with the height of the brick, always available in the face of the wall.

According to Prof. Chorowska\' research, a common feature of the three oldest known castles in Silesia - in Legnica, Wrocław and Wleń - is that earlier in the same places were fortified settlements (whose origins date back to the 10th century), defensive structures surrounded by wood and earth embankments. Under their cover brick palatia were built or, as in the case of Wrocław, monumental residential tower. Although initially each of these residences looked different, after some time even in Wrocław an long palace was built. What these castles had in common is that the palaces coexisted with typically defensive towers, and in the case of Wleń - with peripheral wall.

"They were among of the largest residences in Europe at that time" - noted the researcher.

Asked about the reason for the change in the method of building fortifications - from wood and earthen to brick, the professor said that it was dictated by the ease of construction. "Brick walls did not improve defences, but they were easier to built - not as labour intensive as wood and earthen fortifications" - she added.

"The result confirmed our earlier hypothesis that castles in Silesia were built half a century earlier than thought until now. This phenomenon is associated with political activity of Piast prince Bolesław the Tall" - said the researcher. Prof. Chorowska added that he was one of the exiled sons of Władysław the Exile. The extensive action involving the construction of defensive structures - castles allowed the prince to regain his lost heritage.

The research project was funded by the National Science Centre.

PAP - Science and Scholarship in Poland, Szymon Zdziebłowski

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