“Grandioso finestrone archiacuto a comparti, con magnifica vetrata quattrocentesca, dai meravigliosi smalti colorati. Sebbene molto restaurata, è una delle opere più insigni uscite dalle fornaci muranesi” (Grand compartmented ogival window, with magnificent fifteenth-century stained-glass, decorated with amazing coloured enamels. Even though much restored, it is one of the most eminent artworks produced in Murano furnaces). Such description given by Lorenzetti [1], sets the features of the Grande Vetrata of the SS. Giovanni e Paolo Church in Venice and above all, it considers every single part of which this marvellous work of art is constituted. These different parts are: the stone frame in which the stained-glass window is allocated, the stained-glass window itself (made up of 66 panels), and the grisaille used to decorate the glass tesserae. Looking at the precedent restoration works [2], it has been seen that the problem of the stone wall consolidation arose also in the past. Such a problem, however, was always considered second place as to the grisaille consolidation and to the image conservation. A close up analysis of the artefact was made and all the weathering phenomena were documented. The documentation was carried out for every constituent of the work of art (glass tesserae, metallic retaining structures and stone wall) and particular attention was given to their interactions (i.e. the consequences of the wall movement on the stained-glass window). The diagnostic work was conducted at different stages: characterization of the Building, Technological and Decorative Apparatus; analysis of their weathering and comparison of the data related to each apparatus. The restoration project will have to aim to the consolidation and integration of the grisailles, where it will be necessary, but the consolidation of the stone wall and the rectification of the panels’ deformation will not have to be relegated to the second place.