The liberator of the eastern parts of the Hapsburg Monarchy from the Ottoman Turks, Prince Eugene of Savoy (1663–1736), in addition to his brilliant military career, was also initiator of important town-planning and architectural undertakings. One the one hand, his building activities concerned the construction his own residences in the capital city and various parts of the Monarchy. The second segment of his building activities, which the Prince headed as President of the Imperial War Council, concerned fortress-towns along the new boundary with the Ottoman Empire. They were built based on the knowledge of a strategic genius, they were not just the application of the most modern bastion structures but also contain Baroque ambiences of high urbanistic and architectural quality. The strategic position of today’s eastern Croatian in the context of the former Austrian-Ottoman border resulted in some of the most imposing fortified towns being on Croatian territory - Osijek, Slavonski Brod, and Stara Gradiška. Although the formation of most of the fortress-towns began before Prince Eugene’s era, and continued after him, it was the Prince of Savoy that gave them a key signature. By engaging top military engineers, border fortresses and their fortification systems match projects of the most famous European fortress builder - Vauban. At the same time, by including leading state architects in designing the main public and religious buildings within the fortified encloses, Croatian architecture was here enriched by some anthological examples of Baroque. Since this theme has not been fully explored in the national context, and the international scientific public knows hardly anything about it, the aim of this project is to explore the urbanism and architecture of Osijek, Slavonski Brod, Stara Gradiška, Petrovaradin, and evaluate them in the context of Eugene of Savoy’s other fortifications and residences (on the territory of Austria, Bohemia, Hungary, Romania and Serbia).