Fort National city, built in 1854, has several Haussmannian style buildings characterized by aligned facades of the same height, which form a single architectural set. The front walls are of dressed stone with mouldings and detailed patterns. Their wrought iron balconies add a touch of elegance to their facade. The seismic vulnerability assessment method GNDT (Gruppo Nazionale per la Difesadai Terremoti) is applied, in this paper, for diagnosis of this Haussmannian heritage. This approach is adapted to the reality of this historical heritage in masonry structure. It is based essentially on the influence of structural and non-structural elements and their conservation state over time. This method allows assigning a vulnerability index to each expertized building, and classifying it in a vulnerability level in accordance with its condition. About twenty historical masonry buildings were analyzed using the selected methodology in order to assess the physical damages undergone. A GIS has been developed to gathering and storing the collected information in the field and locating the buildings of the historical area on the satellite maps. Thanks to the thematic analysis, it allows to visualize the expertized buildings according to their performance level to seismic hazard. In addition, it facilitates the structure managers, in making decisions, as to the rehabilitation and restoration of structures or their demolition. The GNDT method coupled with a GIS presents an excellent decision-making tool in hands of expert engineers from the preliminary stage of expertise. This tool allows for predicting the policy management of this architectural heritage during its operation and the monitoring frequency of its structures.