Carol, those cobblestones you have photos of look to be quite flat. The ones I walked on in Eastern Europe were not so even. I can tell you I struggled with the rounded uneven ones in Plovdiv, but I'm a lot older than you are and have problem feet! I always walk with one hiking pole to give me extra balance. I tripped a few times but managed to keep my balance.
This is a great story, but the worst part of cobbletones for me is my four-wheeled suitcase.
I love the thought that you are walking on something that is centuries old! Great story!