It seems like most of central Prague is cobblestone streets and sidewalks. Here's what it looks like when they do road work:
Well, I guess they're probably working on something under the road. They pull up all the stones and put them back later in a kind of arch pattern. Then they throw sand over it and brush it into the cracks. This is just a few feet from the door to our building. You can see the New Town Hall Tower at the end of the street.
You can also see that the sidewalk is cobblestone, although the stones are smaller than the road stones. And you can see a little of the pattern they often incorporate in the sidewalks. This one's really simple, with a border of darker-colored stones, but in other places, they do more complex patterns or even spell out words on the sidewalk. I took some sidewalk pictures just for you!
And here's some road work being done right next to Old Town Square and a picture of the arched pattern of the cobblestone street.