When I visited the ancient city of Ostia ("Ostia Antiqua"), I saw several murals, some on the ground with instructions on how to walk on them, and some stacked

When I visited the ancient city of Ostia ("Ostia Antiqua"), I saw several murals, some on the ground with instructions on how to walk on them, and some stacked vertically with chips that had fallen into the soil. The discovery on the Palatine is impressive, but far from unique. https://en.m.wikipedia.org/wiki/Ostia_Antica https://en.m.wikipedia.org/wiki/Ostia_Antica