The research module deals with stylistic developments in the architecture of the 19th and early 20th century, which are generally referred to as "Heimatstil". Based on examples of buildings in Aachen, a collection of plans will be created that will show the relationship to the local building tradition and, beyond that, to the building practice of the 18th century and to the architectural theory of the Enlightenment. The basis of the research work will be a systematic processing of the plan material from archives and city administration.