The article presents an analysis of the interventions carried out as part of the revitalisation of the complex of tenement houses on Strona Dekerta Starego Miasta na Rynku (Dekert’s Side of the Old Town Market Square) in Warsaw. The design works in question took place between 2014 and 2017, resulting in the reconstruction of the Museum of Warsaw and the adaption of its space to the current needs. The article describes the conservation activities undertaken in the tenement houses over the last one hundred years, the main focus being put on the conditions, project process and final outcome of the revitalisation. As highlighted by the author, the most recent interventions in the Museum of Warsaw’s tenement houses were completed with awareness of the object’s great historic value as an important component of the Old Town inscribed in the UNESCO World Heritage List. They are an example of typically Polish conservation interventions and a specific attitude towards architectural monuments, which were in great part lost by Poland as a result of warfare.