In the architectural field, an important theme is the attention to the material and the traces inherent in it, often the only witnesses of the building’s life stage. Whether you approach, it’s important not to neglect the analysis of the details which, if eliminated, would cause irreversible loss of information.
The basilica of San Simpliciano, located in the square of the same name in Milan, with its long history, has many traces and demonstrates how it is enough to start from a reading of them to expand the knowledge of architectural evolution that made it as it is today. Following is the case of stratigraphic analysis of the South elevation of the transept started following the arched trace on the internal side of the central buttress.

The monument
The building of early Christian origin underwent numerous changes in the Lombard, Romanesque and then Baroque phases, when the external arcades were converted into chapels. Moving on to the restorations, the most important are the “ristauro universale” by Giulio Aluisetti in 1841 and the stylistic restoration of Carlo Maciachini in 1870 to which the neo-Romanesque façade is due. The last interventions made in 1959 and 1972 concerning the apse and the last early Christian parts. Given the long history to date, the structure is a palimpsest for stratigraphic approaches from which any restoration intervention should not ignore.
Study methodology
Assuming that a correct study must always look at the totality of the building, here in order to show how the analysis of a single part can also provide useful data from which to start, we show what has been done on the southern transept. Following the archaeological methods of stratigraphic analysis, we started by identifying the negative or positive (US) stratigraphic units (US) on the elevations of the transept, i.e. all those units that show a phase, an action or a lack of these contact points have been studied to deduce the relative stratigraphic sequence, i.e. which part comes before or after.

Stratigraphic deductions
Through the aforementioned studies it was possible to highlight how the façade narrates several phases characterized by openings, window closings, cuts of protruding spurs and curtain walls, also connected to changes in masonry techniques. Deepening the trace near the buttress, it refers to the footprints usually left by times and then removed. If this were the case, then there would be evidence of a vaulted roof of structures that had to be attached here. An important element of comparison is given by the 1760 print representing the church, made by Giulio Cesare Bianchi.

As you can see in the area of our interest there is a volume leaning against the transept. Another source is a postcard with the church at the same angle as the print.

The aforementioned volume is missing this time, but we can see plasters on the walls that underline the shape of our trace. These clues could be seen as confirmation of the presence of a vaulted structure that no longer exists at the time the photo was taken. The dating of the postcard is not known, but by evaluating the details, references can be identified. For example, the window on the left side of the transept has undergone the top modification from architrave to semicircular documented among the restorations by Aluisetti; this could serve as a guide to frame the photo after 1841. It is then possible to raise the dating again to after 1870 as the facade seems to have already undergone the intervention of Maciachini.
This image is important because it would prove that at the end of the 19th century the volume documented by the oldest print was no longer present but the plaster still remained. This, now removed, would confirm that the trace of our interest is the remaining sign of the vault that was to be grafted here and against which the covering itself ended. As for the identification of the volume, doubts still remain. A clue can be seen in the chronological framework proposed by Claudio Batistini, in which he lists the main events of the church and marks that in 1798 «vengono demoliti l’oratorio di S. Giovanni Battista e la cappella del Corpus Domini posta nella parete meridionale del transetto destro» (Batistini 1979). It could therefore be thought that the chapel in question could be precisely the volume seen in the 1760 print and absent in fact in the postcard.
In order to substantiate the above, further analyzes cannot be ignored, however it is reiterated that the purpose of the reported work is to show how a search can be initiated from simple traces that often risks being deleted from the restorations without first being followed. An analysis like the present one, made with the right approaches, is undoubtedly a simple but important tool not only for the study of the building itself, but also as a preliminary study for interventions. To support any hypothesis on history, however, as archaeology teaches, a fundamental point is the comparison of data. In this case, the research went beyond the direct vision alone, relating to historical views. The interesting fact to highlight is just how the traces fit together as if they were pieces of a puzzle that is up to us, however, to take care to trace, understand and reconstruct.