The article refers to the problem of adaptation of post-fortress objects from the 19th century located in the strict urban tissue in Poland. The authors of the text analyse the example of adaptation of Fort VIII Służew in Warsaw as a way of making common spaces in housing estates more attractive. The rapid demilitarisation of fortresses from this period caused by the development of the art of war and the subsequent dynamic development of urban planning after the Second World War resulted in the degradation and disappearance of these valuable monuments. The Russian ring fortress of Warsaw is now entirely within the urban fabric. Introducing additions and new utility functions is becoming a way of protecting the existing stock of often degraded spaces left behind by former forts. On the example of Fort VIII Służew, a number of activities related to adaptation, revitalisation and revalorisation of the existing urbanised residential space in Ursynów district are presented. The analysed object together with its surroundings is an example of a way to use post-fortress spaces for both utilitarian and cognitive purposes while respecting historic values. Age-old fortifications, so well preserved in Poland, significantly define and shape urban layouts. The research carried out by the authors of this text shows that appropriate use of the potential of post-fortress buildings from the 19th century can significantly improve the quality and character of colonial buildings and highlight the values associated with this type of specific monument.