I don't remember this view but it was easy to figure out that it is very close to the Cathedral of Saint-Quentin and to the Ibis opposite where I had stayed.
And I finally found a reasonable map that shows the presumably "official" trails of both the Via Francigena and the Chemin Estelle/Camino to Santiago going through Saint-Quentin. Comparing it with Google Earth, it confirms my guess that you walked on a Way of Saint James. But you were very very close to the Via Francigena.
More seriously: When I walked, these two trails had not yet been waymarked. No matter how you walk through a town or city on the European continent, you are practically always on a road to or from Santiago and to or from Rome.
Legend:
Red line: Eurovelo Route #3
Blue line with white dots and blue-yellow shell symbol: GR Saint-Jacques de Compostelle
Brown line with yellow dots: GR Via Francigena
(Click to enlarge)
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