In the 1930s, the attention of Turkey's politicians shifted back from Ankara and Anatolian cities to Istanbul. In 1932, the Governorship-Municipality of Istanbul organized an urban design competition for Istanbul, and four foreign city planners were invited. In the meantime, Martin Wagner came to Istanbul for the preparation of urban reports. In 1937, Henri Prost, the prominent urbanist of Paris, was invited to Istanbul and prepared the first master plan of the city In Turkey and in Istanbul, town planning processes have been significantly influenced by "Western" planning principles, cultures, and experiences while gaining a local meaning in the context of Turkish politics and the state-formation process. The aim of this study is to describe the urban design competition of 1933 and the first master plan of 1937. Beyond references to Western European cities as in the 'City-beautiful" planning approach, this study, based on a series of official documents, plan reports and their rhetoric, investigates in particular the role of foreign planners/urbanists in Istanbul in the context of the construction of a nation-state. The analysis of these foreign planners' work suggests that urban planning in Republican Turkey was closely linked to the construction of the nation state.