Belgian block is a pavement made of brick-shaped stones, more or less uniform, but usually rather less than more. Pittsburghers call it “cobblestone,” having lost the memory of what real cobblestones are like. (A real cobblestone is an irregular smooth, round stone, and cobblestone pavements are quite a bit bumpier than Belgian-block pavements.) Countless Belgian-block pavements still exist in Pittsburgh, and often preparations for repaving an asphalt street reveal the Belgian blocks beneath, still perfectly intact, as they will be when archaeologists dig them up a thousand years from now.
This pavement is on an industrial street near the river on the South Side. Old Pa Pitt admits to not knowing the purpose of what appear to be iron spikes in a more or less straight line.