seamless pattern of stone porphyry paving made with porphyry stone blocks of irregular , called opus incertum

irregular shape pattern porfido porphyry paving cobblestones cobble cobblestone stone material floor flooring walkway sidewalk paved block pedestrian zone footpath patio tradition pave building activity old the past historical split splitted opus incertum construction industry stones pavement limestone pathway footway masonry seamless design loopable elements concept concepts texture tileable