Within the "industrial architecture", the thesis is – in a general sense – the story of a travel in the space (from the Liguria sea – but not only – to the Valle dlAosta mountains), and in the time (the XXth century). The structure of the narration previews three main levels of reading: historical-philological, restoring and clearing up, as much clear as possible, on the horizon of the Italian steel iron industry, the vicissitudes in the time of the iron and steel plant "Cogne" of Aosta; geographical/urban, bringing to light the impact of the plant on the city of Aosta and the Valle d'Aosta territory; operative, based on the matter of the dismissed industrial areas and of their reclamation in view of their urban reuse. Cross-sectionally the biographies of some historical figures emerge, up to now enough neglected like those of the entrepreneurs from Ansaldo, Pio and Mario Perrone and of their architect Adolfo Ravinetti, on the background of a dramatic evolution of the Italian society, not only of the steel and iron industry. But we meet also, on the depositor of desires and unaccomplished plans, for Aosta and the Valley, Adriano Olivetti and the BBPR. Which theses for the thesis are found at the end of the job? I will here summarize three of them, of general character: It is the sad history of the failure of an utopy, that one of the Perrone siblings to realize an integral iron and steel process, economically self-sufficient from the mineral to the semi-finished product, between mountains; on the other hand, it is the fascinating history of the challenge of the man on the nature, it is enough – as an example – to think to the complex integrated system (cableways/railways) of transfer to Aosta of the iron mineral extracted from the mines of Cogne. Which destiny in the XXth century for Aosta without the "Cogne"? No reliable answer can be found. Looking "backward" it can be asserted that the Cogne has been the main motor of economic and "political" development of Aosta, helping its physical passage, from village to city, as well as its institutional one, from commune to chief town of province and finally to chief town of region. It is also, and I conclude, the smaller history of a paradox. The inhabitants of Aosta have removed the industrial memory of the city, as however have made the institutions, with the exploitation of the tourist identity and the Roman medieval past compared to the modern one.