Since its establishment as a capital city, the historical topography of Istanbul has witnessed significant changes, created not only by devastating earthquakes and fires, but also by the implementation of large-scale imperial projects. In the existing literature, the transformation of Istanbul's urban area in the nineteenth century has largely explored the topics of new urban regulations, institutions and their implication after the Tanzimat (reform) decree of 1839. This article aims to explore a lesser-known dimension of nineteenth-century developments of the city: the extension of the railway into the heart of Istanbul's historical peninsula, and the spatial change around the Sirkeci district due to the physical expansion of the terminus area. The construction of a larger terminus (inaugurated in 1890) is relatively well documented in architectural history, yet developments prior to this monumental construction have been less explored so far. Thus, this article also aims to investigate the project's development and implementation phases in the second half of the nineteenth century, when the city witnessed continuous urban reformation processes by focusing on the intertwined relations of different agents in the urban space.