This chapter discusses the transformation of urban landscapes, society, and the emergence of masonry buildings in the Middle Ages in the Baltic region. This is achieved by applying the concept of petrifcation and refecting its usability and the possible inconsistencies it entails. Herein, petrifcation is understood as a process of becoming more permanent, solid, stable, concrete, and uniform in terms of both material manifestations and immaterial phenomena, regardless of time and culture.

When explaining processes, the main focus should not be on the premises, reasons or outcomes of the processes but on the actions themselves. However, processes that occurred in the past can be perceived by analysing the manifestations of the transformations. Changes detectable in landscapes and materials demonstrate processes, but when trying to understand the process of transformation the discussion about agency is unavoidable.

By analyzing the factors affecting physical petrifcation in the Middle Ages, we want to demonstrate that petrifcation in matter was intertwined with social and cultural petrifcation and was affected by ideas and needs of the people and ambient conditions. Although seemingly holistic, petrifcation was not an implicit process but was rather organic and adaptable which in turn highlights the problematic nature of the concept