To the Russian intelligentsia, Constantinople had the position of a mythical Jerusalem, argues slavist Suzanne Champonnois in this doctoral dissertation. The dream of an expansion towards the Orient culminating in a conquest of Constantinople was one of the few constants of Russian politics from the foundation of the Russian state until the end of the nineteenth century. However, this desire was legitimized by changing motives, from the protection and liberation of Orthodox Christians in the area, through Pan-Slavic aspirations to geo-political and commercial concerns, particularly maritime access to the West. Of all ideas, the one of religious protection seems to have been the most powerful, and the dream of attending an Orthodox mass in a Hagia Sophia once again converted from mosque to church, was frequently invoked. Through a study of the writings of nineteenth century writers such as Dostoyevsky, Tyutchev and Danilevsky, Champonnois shows that the myth of Constantinople was constructed and spread by intellectuals, but shaped by political circumstances, particularly the Napoleonic and Crimean Wars. The book is written in French.