The identity of the city of Skopje was completely lost after the earthquake in 1963. The buildings from the post – earthquake period were built in Modernist architectural style and they play a major role in creating the new identity of the city. On the other hand, in terms of energy efficiency, these buildings have very poor thermal properties. In order to improve the energy efficiency, retrofit interventions have been constantly implemented and their authentic appearance has been significantly compromised. Many buildings have already been changed to an unrecognizable state, which degrades the architectural identity of Skopje. In order to explore the connection and implication between the reconstruction of the city and the current condition of the buildings in terms of materials, thermal properties, authenticity, degradation and retrofit measures, the methodology of actor network theory (ANT) has been used. The results showed that certain type of buildings are the most vulnerable ones in terms of their energy efficiency issues, sustainability, authentic appearance and in process of significant degradation.