The research focuses mainly on the extraordinary stratigraphy still evident in the ancient urban walls of Cagliari (Sardinia-Italy). The overall interest of this study lies in the fact that it provides a substantial contribution to the definition of a methodology for the study of the growth and transformation of walled cities. The first objective achieved refers to chronostratigraphy and is the experimentation of a methodology capable of dating bricks and stone masonries and the definition of the relative and absolute chronology of structures. More specifically, by means of an archaeological survey, each architectural stratum has been measured and described in relation to its building materials, state of conservation, stratigraphic relationships, also using the Harris matrix. Furthermore, great effort has gone into documenting those parts of the walls that are still authentic, as recent works carried out on consistent portions of these structures have cancelled some relevant stratifications, particularly those referred to historical restoration works. Regarding the tools used, all data has been stored implementing a web-based database (SICaR) developed by the Italian Ministry of Cultural Heritage (MIBAC).