My doctoral work aims to construct a theoretical and intellectual framework to understand a set of remarkable developments concerning the Italian discourse on architecture from the early 1950s to the mid 1970s. This was when the term Rationalism and its theoretical body of work acquired renewed prestige replacing the ephemeral aesthetic of the modernist movement with a grounded discourse based on a deep understanding of the city as background of all architectural artifacts. The main hypothesis of my research is that this return to a rational methodology characterized by a deep understanding of architecture's internal building logic and identifiable in the work and ideas expressed in the International section of the XV Triennale Exhibition of 1973 had a significant and lasting impact on the thinking and formation of architecture culture in Italy and worldwide. This dissertation will thus attempt to construct a matrix of historical and methodological associations and demonstrations that validate and legitimize that rational methodology through a close examination of the work and key concepts of Tendenza, a group of architects in the Italy of the 1960s, pointing out their importance in preparing the ground for the International section of the XV Triennale Exhibition of 1973, which represented a major point of arrival and a point of departure for architecture culture in Italy and worldwide.