The study focuses on the rise of a first generation of architects aware of restoration restoration practices according to the Renaissance cultural and artistic environment, and resulting from classical treatises. How to intervene in medieval pre-existences was a problem that these architects had to face and solve, because despite considering Gothic undesirable, it was essential to find a way to ensure the ‘conformity’ of the building, without violating the mutual ‘harmony’ of its parts, according to the principle of concinnitas, as stated by Alberti. Taking the formulation proposed by Panofsky about the modes of action found in medieval pre-existences: overlay, continuance and compromise, and according to Italian examples previously studied, we sought to evaluate the practice, in Portugal, of this modus operandi. The identification of several national case studies from the Modern period allows us to substantiate this operation and to cast a new view on the conceptual and practical genesis of architectural restoration in Portugal.