The Fortresses in Slavonski Brod and Stara Gradiska, with their border positions, represent remarkable monuments of baroque architecture. They were built as a part of system of the fortresses on the frontier towards Ottoman Empire. The aim of this work is to present informations about fortresses in Slavonia, to restore and improve architecture that was meant for the war into the architecture of peace - to reconcile the past and future and to applicate knowledge of energy management. Nowadays we have to care about our cultural heritage and preserve it in optimal form by implementing suitable new functions like: educational and cultural institutions, galleries, museums, tourist and information centers, hotels ... Also in this time of crisis in the field of construction and investment it is the best time for analizing the current situation and planning activities to create the pre-conditions for stable development and growth in the future by implementing efficient technologies, especially those which will be better, the best possible for our environment.