The current diploma thesis of the Technical University of Vienna is dedicated to the Lviv citadel, its preservation, and modern use. The complex was built in the middle of 19th century for military defense and to control the former capital of the crown land of Galicia and Lodomeria, the city of Lviv. It is situated on the hill south of the old town. The diploma thesis consists of six chapters. Each chapter is dedicated to an important aspect, which explains the value of the object and its location. The first chapter describes the connection between the citadel complex and the old part of the city from a geological, urban, and historical point of view. The second chapter shows the chronological development of the city fortification system, and its connection to the Lviv citadel. The second part is dedicated to the historical circumstances and the theoretical basis of the construction of the citadels in the Austrian monarchy and Europe. The following shows the general structure and the function of the citadel, as well as each of its consisting objects. The next chapter shows the use and transformation of the citadel, elimination of its defense capability, founding of the concentration camp for the prisoners of war, until the new free use of each of the fortification and historical objects. The last, sixth chapter describes the current condition and the present use of the complex. There are included the monument preservation norms, laws, and the options for modern use. The appendix includes the proposed plan of a possible culture-memorial park on the Lviv citadel.