Starting with the squake of Messina (1908), the author analyses from an historical standpoint the different scientific experiences which have influenced the culture and concept of historical city. Above all, he points up the informative approach each earthquake can provide in order to direct the reinforcement interventions to a better understanding of the structures' building tradition. An accurate computerized census of the peculiarities of the old buildings might be useful to manage adequately the reconstrucion of L'Aquila and other damaged cities of the district.