G. De Angelis d’Ossat stated that the restoration of monuments cannot be considered as a cultural product of modern civilisation, but must be understood as a phenomenon that can be traced back to the continuous architectural interventions that have taken place throughout the ages. Before any conservation work is carried out it is necessary to study the building both from the point of view of architectural design and conservation state, as well as material-constructive events that have marked its existence. The constructive reading of historical architecture, through an in-depth analysis of the published and unpublished sources, can be a valuable cognitive tool to acquire all information that constitutes the basis of a conscious restoration intervention. The possibility of consulting and using the archival documents and the historical data they contain is a guarantee of a deeper knowledge and anamnesis of the monument. The interpretation of documentary memories is therefore configured as a concrete cognitive tool and, consequently, a planning tool for restoration work. The key is to understand restoration history as a model of knowledge and a methodology of initial diagnosis to be carried out through history. This paper is conceived as a metaphor of a journey through time and dusty documents that unveils the historical truth of one of the most important Romanesque monuments in southern Italy: St Nicholas’ Basilica in Bari, recounting the interventions that have modified its architectural consistency and decoration, in order to arrive at that cognitive basis, the anamnesis, that consciously guides future conservation interventions.