Accidental Art-Circles

I went for a walk this evening and came across some circles in the pavement. It looks like the circles were put in on purpose, although I have no idea what they were put there for. Cracks started to form that actually connect all of the circles in the sidewalk. I know I have passed them hundreds of times and never really gave them a second thought. But seeing the cracks connecting all of them got me thinking and imagining different things it might represent. Maybe it could be a cool Sunday School lesson, or just something cool to look at, but I definitely saw it in a different light as I walked by this evening.