In this photograph from 1941, currently preserved in the photo library of the Veneranda Fabbrica del Duomo's Archives, one can observe one of the stages in the enormous refurbishment of the naves' floors which began in 1935 and was completed in 1954.As specified in the inventory's description, the photograph we are presenting today shows "the laying of the new floor in the left central nave".
The 6 cm thick marble slabs were gradually replaced starting from the spans in the Northwest corner of the façade, remaining true however to the 16th century design by Pellegrino Pellegrini: the basic decorative element is a small square containing a geometric floral design that repeats in an off-set manner, thus creating a sort of large multi-coloured carpet. The only changes to the original design are in the form of simplifications to the decoration, a legacy of the 19th century.
This type of renovation is necessary due to the uneven wear of the flooring produced by the foot traffic of worshippers and tourists.
The inlaid tiles that cover the surface of the Cathedral's floors are in fact made up of three different kinds of marble: Candoglia marble, black marble fro Varenna, and red marble from Arzo.
It is evident that Candoglia marble tends to deteriorate to a greater extent and more quickly than the red and black marbles: this clearly creates instability, recesses, and, in the most serious cases, the detachment of the inlaid portion.
Hence the need for methodical and regular renovations, maintenance, and monitoring, overseen by the Veneranda Fabbrica construction experts continuously for over six centuries.
The Archives, and specifically the photo library, are open for consultation Tuesday-Friday from 9:30am to 5:30pm, by appointment only.