The topic of the large centrally planned hall is one of the oldest ones in Building History; with different techniques and since Pre-Christian times, builders have always aimed at imagining and realizing a centrally-planned space surmounted by a big roof. Such ambition has never disappeared and today the projects focusing on this topic are innumerable also thanks to the advancements in the construction techniques and to better materials. Do all of these buildings, both the recent and the less recent ones, share features and rules that make them belong to a same family of structural forms? The work we carried out is not meant only to prove that the “genealogical lines” that unite different planning experiences do exist, it aims for something more. Indeed we suppose and then prove that entire families of architectures are referable to formal and structural geometry rules from which we can abstract planning codes that allow modern planners to operate through the permutation of such original types