The city of Firenze represents, for the great variety of its artistic and architectural heritage, a kind of open-air museum. The works of art and monuments are mainly made of rocks outcropping in Firenze and the surrounding areas; a close link, therefore, exists between monuments, geographical position of the city and its history. The use of rocks coming from nearby outcrops allowed limited costs of material transport; indeed, the main rocks used in the architecture of Firenze are the sandstones (Pietra Serena and Pietraforte), extracted from the adjacent quarries. In many churches were also used, for decorative purposes, Marbles, Serpentinites and Limestones; in addition to the natural stones, artificial materials such as Plasters, Mortars and Bricks were used to complete or cover the stone walls. Firenze, like many cities, is characterised by the color of its stones: the warm ochraceous color of the Medieval Pietraforte Sandstone and the cerulean grey of the Renaissance Pietra Serena Sandstone, the white of marbles, the red of limestones, the green of the serpentinites. The knowledge of the city’s lithology provides a material culture, on the wide range of stones used during the different historical periods, which integrates historical and architectural knowledge. Following the colors of Firenze means looking at the city with new eyes and from a different and more careful perspective.