The emergence of the modern city is one of the most defining phenomena of the modern world. In the second half of the nineteenth century, Europe’s urban centres underwent profound planned transformations. Among their most striking examples are capital cities such as Paris, Vienna, Berlin, Brussels, Rome, Madrid, and Budapest. We know a lot, consequently, about urban planning in the centres of political power. We know much less, by contrast, about urban planning in geographical and political peripheries. This thesis explores how urban planning unfolded in Strasbourg and Sarajevo, two cities that were at once peripheral to, and politically dependent on, their respective imperial capitals. From the 1870s, both cities were conquered, occupied, and, eventually, annexed by a central European empire. They became capitals of their respective regions, subject first to military, and, later, imperial administration. The two cities’ imperial predicament crucially shaped their physical development. But with time, the influence of empire diminished. This thesis shows that lateral networks of bourgeois citizens, local politicians, architects and planners had an increasing impact on the development of Strasbourg and Sarajevo. Their influence soon eclipsed the initial dominance of military and imperial hierarchies. By the eve of the First World War, the two cities had become active parts in an international planning discourse, a discourse that transcended regional and imperial boundaries and that connected Strasbourg and Sarajevo more closely to each other, and to other European cities, than at any previous point in their history.