Among Europe’s iconic constructions can be surely named Milan Cathedral, particularly because of the topical moment of the building of its dome, in which have been involved some of the most renowned Renaissance architects, from Donato Bramante to Leonardo da Vinci and Giovanni Antonio Amadeo. Many “secondary” sources exist about its construction and Bramante’s Opinio is one of those. Even if amply studied, it has been analyzed until now essentially for investigating his theoretical ideas on architecture. The paper presents a re-reading of this text in its proper context - the 1487 competition for the dome -, and in the light of the whole building history of the cathedral, to unveil things remained in so far essentially invisible: the many...