Cobblestones.

It's nice to see an old-fashioned skill preserved and used.

IN THE COMMENTS: I'm told these are not cobblestones but Belgian blocks and that these men are not using good technique. Oh, well. It looked nice to me. Made me think the song lyric "Just kicking down the cobblestones... Life I love you, all is groovy." But all is not groovy, because there are no rubber mallets, no levels, not eye protection. Me, I'm impressed by the appearance of skill. I'm dappled and drowsy and ready to sleep...