The thesis studies the concept of the dies natalis templi starting from the work Fastorum libri sex by the poet Publius Ovidius Naso. This synthetic formula refers to the day of birth of the sanctuaries, to be understood as the birthday of the sacred places, grafted into the system of Roman fasti. It is an expression used by some sources, rather through the wording natalis dies, to indicate the event of the creation of a sacred space, which has also been very successful in modern studies on the history of Greco-Roman polytheism. The thesis consists of three broad chapters. In the first, introductory, a review of the studies on the history of the calendar and on the concepts concerning the processes of formation of sacred spaces is presented. The graphic signs, or commas, that appear in some examples of fasti to indicate the natales of the temples are also analysed: the images of these commas were collected and placed in the Appendix at the end of the thesis. The second chapter contains a lexicon of the dies natalis templi starting from Ovid's Fasti. Twenty seven entries are analysed, between verbs and, more rarely, expressions that the poet uses to describe the day of birth of the sacred buildings and its annual recurrence: this is the most important result of the research. In the third chapter three case studies are presented, which confirm and apply the theoretical tool of the lexicon. The dies natalis of the sanctuaries of Aesculapius on the Tiber Island, of Juturna in the Campus Martius and of Minerva Capta on the Mount Celius are studied. These three case studies also constitute individual dossiers, from which significant results have emerged, sometimes independent of the underlying theme of the research. An example is the proposed new edition of a sepulchral inscription that could expand the very scarce information on the Iuturnalia, which are festivals in honor of the goddess Juturna, and on her celebrants.