This article examines the impact of urban transformation and development policies of Mayor Cemil Topuzlu in Istanbul. Topuzlu served two terms as mayor of Istanbul. His first term was on the eve of World War I. His second term coincided with the last year of Turkish War of Independence. These were times when the Ottoman Empire experienced financial crisis as a consequence of wars it fought and the losses it suffered. Despite this unfavourable background, Topuzlu's policies played an important part in the transformation of Istanbul. Topuzlu stayed in Paris as a student of medicine and had already been impressed by urban development projects he witnessed during his stay. When he became mayor, he set out to transform Istanbul into a "European" city. He started wide-ranging expropriation, demolition and development projects. His policies, which were based on "imported" concepts caused controversy and attracted criticism from public and intellectuals of the time. In this article, examples of debate and criticism are quoted from newspapers and other publications of the time. Also, the impact of his transformation policies on the historical and traditional fabric is investigated.