Cobblestone streets are everywhere in Copenhagen. It adds to the character of the city, but I also think it makes it easy to repair anything underground.
I had to stop and watch these men putting in new walks. These small ones all seem to be about the same size and are just hammered into soft sand.
These two men are working together with bigger stones. The one in the back pulls out a stone and measures it with a ruler to make sure it is the right size. He gives it to the man who is hammering them into the sand. Notice the plumb line. A lot of labor involved here as they have to pick up each stone and decide if it will fit and where. They will cover the whole thing with sand when they are finished to fill in the cracks.