Historical studies show that people have been thinking about protection and defence ever since they first started building settlements; that is, from first human encroachment into the environment (in prehistory), when they stopped looking for natural shelters instinctively and consciously started building and living in them. It is not difficult to see that throughout historical development in space human self‑protection has always been expressed in various ways. In fact, this has to do with various measures that people used to protect themselves from wars and in this article they are referred to as strategic urban defence. Above all, this depended on natural conditions (location) but also on the strategic resourcefulness and imagination of individuals in the urban and architectural sense as well as on weapons and other means that were constantly altered throughout history and from war to war. In human historical development there were always people that had an innate talent for warfare (Alexander the Great, Attila and others) as well as for collective self‑protection; that is, strategic urban defence. The case of Ljubljana shows that by the Middle Ages there were military experts in architecture and construction that were in charge of ensuring greater effectiveness in implementing strategic urban defence.