Basing our research on pavements found in Macedonia, Rhodes, Delos, Alexandria and a few other sites in the Greek world, we shall strive to show how polychromy was employed and developed on mortar floors and mosaics from the 5th and 4th centuries B.C. onwards, in both public spaces and private homes. The first objective was to decorate the floors by adding bright colours to extend and enliven the polychromy, an important feature of Greek architectural decor. The second was to copy mural or easel painting, a major art form in this period, itself highly colourful and illusionistic. Owing to the deterioration of the paint and other artificial materials used, this polychromy failed to be spotted at the time of excavation and largely remains to be taken into account. Publication from The 8th round table on ancient polychromy (Paris, 2016) https://doi.org/10.4000/techne.1681.