This paper investigates the mutual effects of cultural diversity and neighbourhood change in three historic neighbourhoods in Istanbul. Through history, some neighbourhoods in Istanbul have been home for people from different cultural and religious backgrounds. In some of these neighbourhoods, cultural diversity still exists. Some other neighbourhoods lose cultural diversity over time. The main reasons of this loss are socio-economic and cultural change, due to gentrification, decay or renewal. The study puts forward a comparative diachronic analysis of the three neighbourhoods, inspecting the relations between cultural diversity and neighbourhood change using space syntax. The change takes place in three levels: the level of socio-economic change, the level of physical change and the level of cultural diversity. The results of the study show that historic neighbourhoods process continuity and change in their own ways. Samatya and Fener, undergo partial neighbourhood decay resulting in downgrading, decay on the built mass and segregation. They respond to cultural diversity differently. Kuzguncuk, is an example of neighbourhood gentrification, which maintains cultural diversity in a more balanced way due to high aesthetic qualities of the buildings, high local integration of the main street, and highly integrated main routes through the neighbourhood.